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NetWare

NetWare is a discontinued computer network operating system developed by Novell, Inc. It initially used cooperative multitasking to run various services on a personal computer, using the IPX network protocol.

The original NetWare product in 1983 supported clients running both CP/M and MS-DOS, ran over a proprietary star network topology and was based on a Novell-built file server using the Motorola 68000 processor. The company soon moved away from building its own hardware, and NetWare became hardware-independent, running on any suitable Intel-based IBM PC compatible system, and able to utilize a wide range of network cards. From the beginning NetWare implemented a number of features inspired by mainframe and minicomputer systems that were not available in its competitors' products.

In 1991, Novell introduced cheaper peer-to-peer networking products for DOS and Windows, unrelated to their server-centric NetWare. These are NetWare Lite 1.0 (NWL), and later Personal NetWare 1.0 (PNW) in 1993.

In 1993, the main NetWare product line took a dramatic turn when version 4 introduced NetWare Directory Services (NDS, later renamed eDirectory), a global directory service based on ISO X.500 concepts (six years later, Microsoft released Active Directory). The directory service, along with a new e-mail system (GroupWise), application configuration suite (ZENworks), and security product (BorderManager) were all targeted at the needs of large enterprises.

By 2000, however, Microsoft was taking more of Novell's customer base and Novell increasingly looked to a future based on a Linux kernel. The successor to NetWare, Open Enterprise Server (OES), released in March 2005, offers all the services previously hosted by NetWare 6.5, but on a SUSE Linux Enterprise Server; the NetWare kernel remained an option until OES 11 in late 2011.

The final update release was version 6.5SP8 of May 2009; NetWare is no longer on Novell's product list. NetWare 6.5SP8 General Support ended in 2010; Extended Support was available until the end of 2015, and Self Support until the end of 2017. The replacement is Open Enterprise Server.

History
NetWare evolved from a very simple concept: file sharing instead of disk sharing. By controlling access at the level of individual files, instead of entire disks, files could be locked and better access control implemented. In 1983 when the first versions of NetWare originated, all other competing products were based on the concept of providing shared direct disk access. Novell's alternative approach was validated by IBM in 1984, which helped promote the NetWare product.

Novell NetWare shares disk space in the form of NetWare volumes, comparable to logical volumes. Client workstations running DOS run a special terminate and stay resident (TSR) program that allows them to map a local drive letter to a NetWare volume. Clients log into a server in order to be allowed to map volumes, and access can be restricted according to the login name. Similarly, they can connect to shared printers on the dedicated print server, and print as if the printer is connected locally.

At the end of the 1990s, with Internet connectivity booming, the Internet's TCP/IP protocol became dominant on LANs. Novell had introduced limited TCP/IP support in NetWare 3.x (c. 1992) and 4.x (c. 1995), consisting mainly of FTP services and UNIX-style LPR/LPD printing (available in NetWare 3.x), and a Novell-developed webserver (in NetWare 4.x). Native TCP/IP support for the client file and print services normally associated with NetWare was introduced in NetWare 5.0 (released in 1998). There was also a short-lived product, NWIP, that encapsulated IPX in TCP/IP, intended to ease transition of an existing NetWare environment from IPX to IP.

During the early to mid-1980s Microsoft introduced their own LAN system in LAN Manager, based on the competing NBF protocol. Early attempts to compete with NetWare failed, but this changed with the inclusion of improved networking support in Windows for Workgroups, and then the successful Windows NT and Windows 95. NT, in particular, offered a sub-set of NetWare's services, but on a system that could also be used on a desktop, and due to the vertical integration there was no need for a third-party client.

Early years
NetWare originated from consulting work by SuperSet Software, a group founded by the friends Drew Major, Dale Neibaur, Kyle Powell and later Mark Hurst. This work stemmed from their classwork at Brigham Young University in Provo, Utah, starting in October 1981.

In 1981, Raymond Noorda engaged the work by the SuperSet team. The team was originally assigned to create a CP/M disk sharing system to help network the Motorola 68000-based hardware that Novell sold at the time. The first S-Net is CP/M-68K-based and shares a hard disk. In 1983, the team was privately convinced that CP/M was a doomed platform and instead came up with a successful file-sharing system for the newly introduced IBM-compatible PC. They also wrote an application called Snipes – a text-mode game – and used it to test the new network and demonstrate its capabilities. Snipes [aka 'NSnipes' for 'Network Snipes'] is the first network application ever written for a commercial personal computer, and it is recognized as one of the precursors of many popular multiplayer games such as Doom and Quake.

First called ShareNet or S-Net, this network operating system (NOS) was later called Novell NetWare. NetWare is based on the NetWare Core Protocol (NCP), which is a packet-based protocol that enables a client to send requests to and receive replies from a NetWare server. Initially, NCP was directly tied to the IPX/SPX protocol, and NetWare communicated natively using only IPX/SPX.

The first product to bear the NetWare name was released in 1983. The original product, NetWare 68 (AKA S-Net), ran on Novell's proprietary 68000-based file server hardware, and used a star network topology. This was later joined by NetWare 86, which could use conventional Intel 8086-based PCs for the server. This was replaced in 1985 with Advanced NetWare 86, which allowed more than one server on the same network. In 1986, after the Intel 80286 processor became available, Novell released Advanced NetWare 286. Two versions were offered for sale; the basic version was sold as ELS I, plus an enhanced version, ELS II. *ELS* stood for "Entry Level System".

NetWare 286 2.x
Advanced NetWare version 2.x, launched in 1986, was written for the then-new 80286 CPU. The 80286 CPU features a new 16-bit protected mode that provides access to up to 16 MiB RAM as well as new mechanisms to aid multi-tasking. (Prior to the 80286, PC CPU servers used the Intel 8088/8086 8-/16-bit processors, which are limited to an address space of 1 MiB with not more than 640 KiB of directly addressable RAM.) The combination of a higher 16 MiB RAM limit, 80286 processor feature utilization, and 256 MB NetWare volume size limit (compared to the 32 MB that DOS allowed at that time) allowed the building of reliable, cost-effective server-based local area networks for the first time. The 16 MiB RAM limit was especially important, since it makes enough RAM available for disk caching to significantly improve performance. This became the key to Novell's performance while also allowing larger networks to be built.

In a significant innovation, NetWare 286 is also hardware-independent, unlike competing network server systems. Novell servers can be assembled using any brand system with an Intel 80286 CPU, any MFM, RLL, ESDI, or SCSI hard drive and any 8- or 16-bit network adapter for which NetWare drivers are available – and 18 different manufacturer's network cards were supported at launch.

The server could support up to four network cards, and these can be a mixture of technologies such as ARCNET, Token Ring and Ethernet. The operating system is provided as a set of compiled object modules that required configuration and linking. Any change to the operating system requires a re-linking of the kernel. Installation also requires the use of a proprietary low-level format program for MFM hard drives called COMPSURF.

The file system used by NetWare 2.x is NetWare File System 286, or NWFS 286, supporting volumes of up to 256 MB. NetWare 286 recognizes 80286 protected mode, extending NetWare's support of RAM from 1 MiB to the full 16 MiB addressable by the 80286. A minimum of 2 MiB is required to start up the operating system; any additional RAM is used for FAT, DET and file caching. Since 16-bit protected mode is implemented in the 80286 and every subsequent Intel x86 processor, NetWare 286 version 2.x will run on any 80286 or later compatible processor.

NetWare 2.x implements a number of features inspired by mainframe and minicomputer systems that were not available in other operating systems of the day. The System Fault Tolerance (SFT) features includes standard read-after-write verification (SFT-I) with on-the-fly bad block re-mapping (at the time, disks did not have that feature built in) and software RAID1 (disk mirroring, SFT-II). The Transaction Tracking System (TTS) optionally protects files against incomplete updates. For single files, this requires only a file attribute to be set. Transactions over multiple files and controlled roll-backs are possible by programming to the TTS API.

NetWare 286 2.x normally requires a dedicated PC to act as the server, where the server uses DOS only as a boot loader to execute the operating system file NET$OS.EXE. All memory is allocated to NetWare; no DOS ran on the server. However, a "non-dedicated" version was also available for price-conscious customers. In this, DOS 3.3 or higher remains in memory, and the processor time-slices between the DOS and NetWare programs, allowing the server computer to be used simultaneously as a network file server and as a user workstation. Because all extended memory (RAM above 1 MiB) is allocated to NetWare, DOS is limited to only 640 KiB; expanded memory managers that used the MMU of 80386 and higher processors, such as EMM386, do not work; 8086-style expanded memory on dedicated plug-in cards is possible however. Time slicing is accomplished using the keyboard interrupt, which requires strict compliance with the IBM PC design model, otherwise performance is affected.

Server licensing on early versions of NetWare 286 is accomplished by using a key card. The key card was designed for an 8-bit ISA bus, and has a serial number encoded on a ROM chip. The serial number has to match the serial number of the NetWare software running on the server. To broaden the hardware base, particularly to machines using the IBM MCA bus, later versions of NetWare 2.x do not require the key card; serialised license floppy disks are used in place of the key cards.

Licensing is normally for 100 users, but two ELS versions were also available. First a 5-user ELS in 1987, and followed by the 8-user ELS 2.12 II in 1988.

NetWare 3.x
NetWare's 3.x range was a major step forward. It began with version 3.0 in 1990, followed quickly by version 3.10 and 3.11 in 1991.

A key feature was support for 32-bit protected mode, eliminating the 16 MiB memory limit of NetWare 286 and therefore allowing larger hard drives to be supported (since NetWare 3.x cached the entire file allocation table and directory entry table into memory for improved performance).

NetWare version 3.x was also much simpler to install, with disk and network support provided by software modules called a NetWare Loadable Module (NLM) loaded either at start-up or when it was needed. NLMs could also add functionality such as anti-virus software, backup software, database and web servers. Support for long filenames was also provided by an NLM.

A new file system was introduced by NetWare 3.x – "NetWare File System 386", or NWFS 386, which significantly extended volume capacity (1 TB, 4 GB files), and could handle up to 16 volume segments spanning multiple physical disk drives. Volume segments could be added while the server was in use and the volume was mounted, allowing a server to be expanded without interruption.

In NetWare 386 3.x all NLMs ran on the server at the same level of processor memory protection, known as "ring 0". This provided the best possible performance, it sacrificed reliability because there was no memory protection, and furthermore NetWare 3.x used a co-operative multitasking model, meaning that an NLM was required to yield to the kernel regularly. For either of these reasons a badly behaved NLM could result in a fatal (ABEND) error.

NetWare continued to be administered using console-based utilities.

With version 3.x, Novell increased the rigors of compatibility testing with their third-party vendors, revamping their certification program in October 1992 and unveiling a two-tier cooperating marketing program. The first tier provided Novell's vendors a package containing a compatibility guideline book, engineering support lines, self-testing tools, and limited marketing resources, the latter including a license to promote products with a logo stating "Yes, it runs with NetWare" – all free of charge and followed at the vendors' discretion. The second tier required a one-time application fee of $7,000 but replaced the logo's byline with a more confident-sounding "Yes, it's NetWare tested and approved" and accorded partners with more extensive support, including on-location testing by Novell Labs. Initially limited to the United States, this program was rolled out in the United Kingdom in the following year.

For a while, Novell also marketed an OEM version of NetWare 3, called Portable NetWare, together with OEMs such as Hewlett-Packard, DEC and Data General, who ported Novell source code to run on top of their Unix operating systems. Portable NetWare did not sell well.

While NetWare 3.x was current, Novell introduced its first high-availability clustering system, named NetWare SFT-III, which allowed a logical server to be completely mirrored to a separate physical machine. Implemented as a shared-nothing cluster, under SFT-III the OS was logically split into an interrupt-driven I/O engine and the event-driven OS core. The I/O engines serialized their interrupts (disk, network etc.) into a combined event stream that was fed to two identical copies of the system engine through a fast (typically 100 Mbit/s) inter-server link. Because of its non-preemptive nature, the OS core, stripped of non-deterministic I/O, behaves deterministically, like a large finite state machine. The outputs of the two system engines were compared to ensure proper operation, and two copies fed back to the I/O engines. Using the existing SFT-II software RAID functionality present in the core, disks could be mirrored between the two machines without special hardware. The two machines could be separated as far as the server-to-server link would permit. In case of a server or disk failure, the surviving server could take over client sessions transparently after a short pause since it had full state information. SFT-III was the first NetWare version able to make use of SMP hardware – the I/O engine could optionally be run on its own CPU. NetWare SFT-III, ahead of its time in several ways, was a mixed success.

With NetWare 3 an improved routing protocol, NetWare Link Services Protocol, has been introduced which scales better than Routing Information Protocol and allows building large networks.

NetWare 4.x
Version 4 in 1993 introduced NetWare Directory Services, later re-branded as Novell Directory Services (NDS), based on X.500, which replaced the Bindery with a global directory service, in which the infrastructure was described and managed in a single place. Additionally, NDS provided an extensible schema, allowing the introduction of new object types. This allowed a single user authentication to NDS to govern access to any server in the directory tree structure. Users could therefore access network resources no matter on which server they resided, although user license counts were still tied to individual servers. (Large enterprises could opt for a license model giving them essentially unlimited per-server users if they let Novell audit their total user count.)

Version 4 also introduced a number of useful tools and features, such as transparent compression at file system level and RSA public/private encryption.

Another new feature was the NetWare Asynchronous Services Interface (NASI). It allowed network sharing of multiple serial devices, such as modems. Client port redirection occurred via a DOS or Windows driver allowing companies to consolidate modems and analog phone lines.

NetWare for OS/2
Promised as early as 1988, when the Microsoft-IBM collaboration was still ongoing and OS/2 1.x was still a 16-bit product, the product didn't become commercially available until after IBM and Microsoft had parted ways and OS/2 2.0 had become a 32-bit, pre-emptive multitasking and multithreading OS.

By August 1993, Novell released its first version of "NetWare for OS/2". This first release supported OS/2 2.1 (1993) as the base OS, and required that users first buy and install IBM OS/2, then purchase NetWare 4.01, and then install the NetWare for OS/2 product. It retailed for $200.

By around 1995, and coincidental with IBM's renewed marketing push for its 32-bit OS/2 Warp OS, both as a desktop client and as a LAN server (OS/2 Warp Server), NetWare for OS/2 began receiving some good press coverage. "NetWare 4.1 for OS/2" allowed to run Novell's network stack and server modules on top of IBM's 32-bit kernel and network stack. It was basically NetWare 4.x running as a service on top of OS/2. It was compatible with third party client and server utilities and NetWare Loadable Modules.

Since IBM's 32-bit OS/2 included Netbios, IPX/SPX and TCP/IP support, this means that sysadmins could run all three most popular network stacks on a single box, and use the OS/2 box as a workstation too. NetWare for OS/2 shared memory on the system with OS/2 seamlessly. The book "Client Server survival Guide with OS/2" described it as "glue code that lets the unmodified NetWare 4.x server program think it owns all resources on a OS/2 system". It also claimed that a NetWare server running on top of OS/2 only suffered a 5% to 10% overhead over NetWare running over the bare metal hardware, while gaining OS/2's pre-emptive multitasking and object oriented GUI.

Novell continued releasing bugfixes and updates to NetWare for OS/2 up to 1998.

Strategic mistakes
Novell's strategy with NetWare 286 2.x and 3.x proved very successful; before the arrival of Windows NT Server, Novell claimed 90% of the market for PC based servers.

However, the design of NetWare 3.x and later involved a DOS partition to load NetWare server files. While of little technical import, this feature became a liability due to the system administration it required. Compounding this, the NetWare console remained text-based at a time the Windows graphical interface gained widespread acceptance. Especially new users preferred the Windows graphical interface to learning DOS commands necessary to build and control a NetWare server. Novell could have eliminated at least the separately bootable DOS partition requirement at the outset, by retaining the design of NetWare 286, which installed the server file into a Novell partition and allowed the server to boot from the Novell partition without creating a bootable DOS partition. Novell finally added support for this in a Support Pack for NetWare 6.5.

As Novell initially used IPX/SPX instead of TCP/IP, they were poorly positioned to take advantage of the Internet in 1995. This resulted in Novell servers being bypassed for routing and Internet access in favor of hardware routers, Unix-based operating systems such as FreeBSD, and SOCKS and HTTP Proxy Servers on Windows and other operating systems.

A decision by the management of Novell also took away the ability of independent resellers and engineers to recommend and sell the product. The reduction of their effective sales force created this downward spiral in sales.

NetWare 4.1x and NetWare for Small Business
Novell priced NetWare 4.10 similarly to NetWare 3.12, allowing customers who resisted NDS (typically small businesses) to try it at no cost.

Later Novell released NetWare version 4.11 in 1996 which included many enhancements that made the operating system easier to install, easier to operate, faster, and more stable. It also included the first full 32-bit client for Microsoft Windows-based workstations, SMP support and the NetWare Administrator (NWADMIN or NWADMN32), a GUI-based administration tool for NetWare. Previous administration tools used the Cworthy interface, the character-based GUI tools such as SYSCON and PCONSOLE with blue text-based background. Some of these tools survive to this day, for instance MONITOR.NLM.

Novell packaged NetWare 4.11 with its Web server, TCP/IP support and the Netscape browser into a bundle dubbed IntranetWare (also written as intraNetWare). A version designed for networks of 25 or fewer users was named IntranetWare for Small Business and contained a limited version of NDS and tried to simplify NDS administration. The intranetWare name was dropped in NetWare 5.

During this time Novell also began to leverage its directory service, NDS, by tying their other products into the directory. Their e-mail system, GroupWise, was integrated with NDS, and Novell released many other directory-enabled products such as ZENworks and BorderManager.

NetWare still required IPX/SPX as NCP used it, but Novell started to acknowledge the demand for TCP/IP with NetWare 4.11 by including tools and utilities that made it easier to create intranets and link networks to the Internet. Novell bundled tools, such as the IPX/IP gateway, to ease the connection between IPX workstations and IP networks. It also began integrating Internet technologies and support through features such as a natively hosted web server.

NetWare 5.x
With the release of NetWare 5 in October 1998 Novell switched its primary NCP interface from the IPX/SPX network protocol to TCP/IP to meet market demand. Products continued to support IPX/SPX, but the emphasis shifted to TCP/IP. New features included:

 * a GUI for NetWare
 * Novell Storage Services (NSS), a file system to replace the traditional NetWare File System (which Novell continued to support)
 * Java virtual machine for NetWare
 * Novell Distributed Print Services (NDPS), an infrastructure for printing over networks
 * ConsoleOne, a Java-based GUI administration console
 * directory-enabled Public key infrastructure services (PKIS)
 * directory-enabled DNS and DHCP servers
 * support for Storage Area Networks (SANs)
 * Novell Cluster Services (NCS), a replacement for SFT-III
 * Oracle 8i with a 5-user license

The Cluster Services improved on SFT-III, as NCS did not require specialized hardware or identical server configurations.

Novell released NetWare 5 during a time when NetWare's market share had started dropping precipitously; many companies and organizations replaced their NetWare servers with servers running Microsoft's Windows NT operating system.

Around this time Novell also released their last upgrade to the NetWare 4 operating system, NetWare 4.2.

NetWare 5 and above supported Novell NetStorage for Internet-based access to files stored within NetWare. Novell released NetWare 5.1 in January 2000. It introduced a number of tools, such as:

 * IBM WebSphere Application Server
 * NetWare Management Portal (later called Novell Remote Manager), web-based management of the operating system
 * FTP, NNTP and streaming-media servers
 * NetWare Web Search Server
 * WebDAV support

NetWare 6.0
NetWare 6 was released in October 2001, shortly after its predecessor. This version has a simplified licensing scheme based on users, not server connections. This allows unlimited connections per user to any number of NetWare servers in the network. Novell Cluster Services was also improved to support 32-node clusters; the base NetWare 6.0 product included a two-node clustering license.

NetWare 6.5
NetWare 6.5 was released in August 2003. Some of the new features in this version included:

 * more open-source products such as PHP, MySQL and OpenSSH
 * a port of the Bash shell and a lot of traditional Unix utilities such as wget, grep, awk and sed to provide additional capabilities for scripting
 * iSCSI support (both target and initiator)
 * Virtual Office – an "out of the box" web portal for end users providing access to e-mail, personal file storage, company address book, etc.
 * Domain controller functionality
 * Universal password
 * DirXML Starter Pack – synchronization of user accounts with another eDirectory tree, a Windows NT domain or Active Directory.
 * exteNd Application Server – a Java EE 1.3-compatible application server
 * support for customized printer driver profiles and printer usage auditing
 * NX bit support
 * support for USB storage devices
 * support for encrypted volumes

The latest – and apparently last – Service Pack for NetWare 6.5 is SP8, released May 2009.

1.0
In 2003, Novell announced the successor product to NetWare: Open Enterprise Server (OES). First released in March 2005, OES completes the separation of the services traditionally associated with NetWare (such as Directory Services, and file-and-print) from the platform underlying the delivery of those services. OES is essentially a set of applications (eDirectory, NetWare Core Protocol services, iPrint, etc.) that can run atop either a Linux or a NetWare kernel platform. Clustered OES implementations can even migrate services from Linux to NetWare and back again, making Novell one of the very few vendors to offer a multi-platform clustering solution.

Consequent to Novell's acquisitions of Ximian and the German Linux distributor SuSE, Novell moved away from NetWare and shifted its focus towards Linux. Marketing was focused on getting faithful NetWare users to move to the Linux platform for future releases. The clearest indication of this direction was Novell's controversial decision to release Open Enterprise Server on Linux only, not NetWare. Novell later watered down this decision and stated that NetWare's 90 million users would be supported until at least 2015. Meanwhile, many former NetWare customers rejected the confusing mix of licensed software running on an open-source Linux operating system in favor of moving to complete Open Source solutions such as those offered by Red Hat.

2.0
OES 2 was released on 8 October 2007. It includes NetWare 6.5 SP7, which supports running as a paravirtualized guest inside the Xen hypervisor and new Linux based version using SLES10.
 * New features include:

 * 64-bit support
 * Virtualization
 * Dynamic Storage Technology, which provide Shadow Volumes
 * Domain services for Windows (provided in OES 2 service pack 1)

From the 1990s
some organizations still used Novell NetWare, but it had started to lose popularity from the mid-1990s, when NetWare was the de facto standard for file- and printer-sharing software for the Intel x86 server platform.

Microsoft successfully took market share from NetWare products from the late-1990s. Microsoft's more aggressive marketing was aimed directly at non-technical management through major magazines, while Novell NetWare's was through more technical magazines read by IT personnel.

Novell did not adapt their pricing structure to current market conditions, and NetWare sales suffered.

NetWare Lite / Personal NetWare
NetWare Lite and Personal NetWare were a series of peer-to-peer networks developed by Novell for DOS- and Windows-based computers aimed at personal users and small businesses between 1991 and 1995.

Performance
NetWare dominated the network operating system (NOS) market from the mid-1980s through the mid- to late-1990s due to its extremely high performance relative to other NOS technologies. Most benchmarks during this period demonstrated a 5:1 to 10:1 performance advantage over products from Microsoft, Banyan, and others. One noteworthy benchmark pitted NetWare 3.x running NFS services over TCP/IP (not NetWare's native IPX protocol) against a dedicated Auspex NFS server and an SCO Unix server running NFS service. NetWare NFS outperformed both 'native' NFS systems and claimed a 2:1 performance advantage over SCO Unix NFS on the same hardware.

The reasons for NetWare's performance advantage are given below.

File service instead of disk service
When first developed, nearly all LAN storage was based on the disk server model. This meant that if a client computer wanted to read a particular block from a particular file it would have to issue the following requests across the relatively slow LAN:

NetWare, since it was based on a file service model, interacted with the client at the file API level: All of the work of searching the directory to figure out where the desired data was physically located on the disk was performed at high speed locally on the server. By the mid-1980s, most NOS products had shifted from the disk service to the file service model. Today, the disk service model is making a comeback, see SAN.
 * 1) Read first block of directory
 * 2) Continue reading subsequent directory blocks until the directory block containing the information on the desired file was found, could be many directory blocks
 * 3) Read through multiple file entry blocks until the block containing the location of the desired file block was found, could be many directory blocks
 * 4) Read the desired data block
 * 1) Send file open request (if this hadn't already been done)
 * 2) Send a request for the desired data from the file

Aggressive caching
From the start, the NetWare design focused on servers with copious amounts of RAM. The entire file allocation table (FAT) was read into RAM when a volume was mounted, thereby requiring a minimum amount of RAM proportional to online disk space; adding a disk to a server would often require a RAM upgrade as well. Unlike most competing network operating systems prior to Windows NT, NetWare automatically used all otherwise unused RAM for caching active files, employing delayed write-backs to facilitate re-ordering of disk requests (elevator seeks). An unexpected shutdown could therefore corrupt data, making an uninterruptible power supply practically a mandatory part of a server installation.

The default dirty cache delay time was fixed at 2.2 seconds in NetWare 286 versions 2.x. Starting with NetWare 386 3.x, the dirty disk cache delay time and dirty directory cache delay time settings controlled the amount of time the server would cache changed ("dirty") data before saving (flushing) the data to a hard drive. The default setting of 3.3 seconds could be decreased to 0.5 seconds but not reduced to zero, while the maximum delay was 10 seconds. The option to increase the cache delay to 10 seconds provided a significant performance boost. Windows 2000 and 2003 server do not allow adjustment to the cache delay time. Instead, they use an algorithm that adjusts cache delay.

Efficiency of NetWare Core Protocol (NCP)
Most network protocols in use at the time NetWare was developed didn't trust the network to deliver messages. A typical client file read would work something like this:

 * 1) Client sends read request to server
 * 2) Server acknowledges request
 * 3) Client acknowledges acknowledgement
 * 4) Server sends requested data to client
 * 5) Client acknowledges data
 * 6) Server acknowledges acknowledgement

In contrast, NCP was based on the idea that networks worked perfectly most of the time, so the reply to a request served as the acknowledgement. Here is an example of a client read request using this model:

 * 1) Client sends read request to server
 * 2) Server sends requested data to client

All requests contained a sequence number, so if the client didn't receive a response within an appropriate amount of time it would re-send the request with the same sequence number. If the server had already processed the request it would resend the cached response, if it had not yet had time to process the request it would only send a "positive acknowledgement". The bottom line to this 'trust the network' approach was a 2/3 reduction in network transactions and the associated latency.

Non-preemptive OS designed for network services
One of the raging debates of the 1990s was whether it was more appropriate for network file service to be performed by a software layer running on top of a general purpose operating system, or by a special purpose operating system. NetWare was a special purpose operating system, not a timesharing OS. It was written from the ground up as a platform for client-server processing services. Initially it focused on file and print services, but later demonstrated its flexibility by running database, email, web and other services as well. It also performed efficiently as a router, supporting IPX, TCP/IP, and Appletalk, though it never offered the flexibility of a 'hardware' router.

In 4.x and earlier versions, NetWare did not support preemption, virtual memory, graphical user interfaces, etc. Processes and services running under the NetWare OS were expected to be cooperative, that is to process a request and return control to the OS in a timely fashion. On the down side, this trust of application processes to manage themselves could lead to a misbehaving application bringing down the server.

title: NetWare


text:
Brazilian aircraft carrier Minas Gerais

NAeL Minas Gerais (pennant number A 11) was a Colossus-class aircraft carrier light aircraft carrier operated by the Marinha do Brasil (MB, Brazilian Navy) from 1960 until 2001. The ship was laid down for the United Kingdom's Royal Navy during World War II as HMS Vengeance, was completed shortly before the war's end, and did not see combat. After stints as a training vessel and Arctic research ship, the carrier was loaned to the Royal Australian Navy from 1952 to 1955. She was returned to the British, who sold her to Brazil in 1956.

The ship underwent a four-year conversion in the Netherlands to make her capable of operating heavier naval aircraft. She was commissioned into the MB as Minas Gerais (named after the state of Minas Gerais) in 1960; the first purchased by a Latin American nation, and the second to enter service, behind the Argentinian ARA Independencia (also Colossus-class). Between 1987 and 1996, the carrier was unable to operate fixed-wing aircraft because of a defective catapult, and was retasked as a helicopter carrier and amphibious assault ship.

Minas Gerais remained in service until 2001, when she was replaced by NAe BRAZILIAN AIRCRAFT CARRIER São Paulo. At the time of her decommissioning, she was the oldest operational aircraft carrier in the world, and the last operational unit of the World War II Light Fleet design. Despite attempts to preserve the carrier as a museum ship, and after several failed attempts to auction the ship off (including a listing on eBay), Minas Gerais was sold for scrap in 2004 and taken to Alang, India for breaking up.

Design and construction
The carrier was constructed by Swan Hunter for the Royal Navy (RN) as HMS Vengeance. She was laid down on 16 November 1942, and launched on 23 February 1944. Construction was completed on 15 January 1945, and Vengeance was commissioned into the RN.

The Colossus-class carriers were intended to be 'disposable warships': they were to be operated during World War II and scrapped at the end of hostilities or within three years of entering service. Despite this plan, the ship had a service life of over 55 years across three navies.

Early operational history
After commissioning, Vengeance was assigned to the 11th Aircraft Carrier Squadron, which was attached to the British Pacific Fleet. The carrier arrived in Sydney, Australia in July 1945, but remained in the harbour for refits until the end of World War II. Vengeance operated in the waters of Asia until mid-1946, when she returned to England and was reassigned as a training vessel. In late 1948, Vengeance was converted for Arctic conditions, and from February 1949 to March 1949, she operated in Arctic waters as part of an experimental cruise to determine how well ships, aircraft, and personnel functioned in extreme cold.

From late 1952 until mid-1955, Vengeance was loaned to the Royal Australian Navy, to serve in place of the under-construction HMAS Melbourne (R21).

Purchase and modernisation
During the leadup to the 1955 presidential election, Juscelino Kubitschek de Oliveira, governor of the state of Minas Gerais promised Brazilian admirals to acquire an aircraft carrier for the Marinha do Brasil (MB, Brazilian Navy). Kubitschek later claimed that this was to avoid a naval rebellion during his inauguration at the start of 1956, and despite believing in the "military uselessness" of the second-hand warship, the sale of Vengeance to Brazil for US$9 million went through on 14 December 1956.

From mid-1957 until December 1960, the carrier underwent a massive refit and reconstruction in the Netherlands. The work was carried out by Verolme Dock in Rotterdam, and cost US$27 million. The most visible change was the installation of an 8.5-degree angled flight deck. The size of the angle required that an accessway be built around the starboard side of the island superstructure; the weight acting as a counterbalance for the flight deck's portside overhang. Combined with the fitting of a more powerful steam catapult, stronger arresting gear, reinforced hangar elevators, and a mirror landing aid, these modifications permitted the operation of jet aircraft up to 20000 lb in weight. The carrier's island superstructure was replaced, and a lattice mast was fitted to support the new fire control system and radar suite. The ship's boiler capacity was increased, and internal electricity was converted to AC through the installation of four turbo generators and one diesel generator.

The carrier was commissioned into the Marinha do Brasil as NAeL Minas Gerais (named for Kubitschek's home state) on 6 December 1960. She departed Rotterdam for Rio de Janeiro on 13 January 1961. The duration of the refit meant that while the carrier was the first purchased by a Latin American nation, she was the second to enter service, after another Colossus-class carrier entered service with the Argentine Navy as ARA Independencia in July 1959.

Weapons and systems
During the ship's modernisation refit to become Minas Gerais, her armament was altered to consist of ten Bofors 40 mm anti-aircraft guns (2 quad mountings and 1 twin mounting), and two 47 mm saluting guns. In 1994, the Bofors were removed and replaced with two twin surface-to-air launchers for Mistral missiles. If additional armament was required, the Bofors could be reinstalled.

By 1996, Minas Gerais was fitted with the following radars: a Lockheed SPS-40B for air search, a Plessey AWS 4 for surface search, a Signaal ZW06 for navigation, two SPG-34 for fire control, and a Scanter Mil-Par for Carrier-Controlled Approach. The two search radars operate on NATO frequency bands designated E and F, the navigation and CCA radars operate on the NATO I band, and the fire control radars on both the I and J bands.

As of the mid-1990s, the carrier's air group consisted of six S-2E Trackers, four to six ASH-3D Sea Kings, two AS-355 Ecureuils, and three A-332 Super Pumas. In 1999, the MB acquired 20 A-4KU Skyhawks and 3 TA-4KU trainer aircraft from the Kuwait Air Force for $US70 million. Minas Gerais began operating these aircraft in late 2000.

Brazilian operational history

In 1965, President Humberto de Alencar Castelo Branco permitted the operation of helicopters to the Navy, fixed-wing aircraft were to remain the responsibility of the Força Aérea Brasileira (FAB, Brazilian Air Force). As a result, Minas Gerais was required to embark two air groups: the Navy operated helicopters while the Air Force operated S-2 Tracker aircraft. Consequently, the ship spent most of her Brazilian career operating as an anti-submarine warfare carrier.

From 1976 to 1981, the ship underwent a major refit. Work included the installation of a datalink to improve co-operation with Niterói-class frigates, updates to the radar suite, and other work to extend the carrier's life expectancy into the 1990s. In 1988, engine problems, combined with the inability for Argentina to fund a required modernisation of ARA Veinticinco de Mayo, saw the Argentine Colossus-class carrier confined to port, making Minas Gerais the only active aircraft carrier in the South American region. In December 1987, Minas Gerais herself was laid up after participating in Operation Dragon XXIII because of problems with her aircraft catapult. Although unable to operate as an aircraft carrier, the ship saw use over the following years in training exercises as an amphibious assault ship; using an air group of Eurocopter AS532 Cougar and Eurocopter AS350 Squirrel helicopters to transport Marines ashore.

Minas Gerais underwent a modernisation refit from July 1991 to October 1993. This included the overhaul of the boilers and engines, integration of a SICONTA command system, two new navigation radars and Scanter-MIL landing radar were installed, and preparation for the installation of Simbad launchers for Mistral surface-to-air missiles. The launchers themselves were installed in 1994, with the ten Bofors removed at the same time. The Bofors could be reinstalled to complement the ship's armament if needed. In November 1993, the carrier conducted a joint exercise with the Argentine Navy, where Argentine pilots flying Dassault-Breguet Super Étendard aircraft performed 177 touch-and-go landings, in order to maintain their carrier landing qualifications while Veinticinco de Mayo was out of service.

During 1995 and 1996, the ability to operate fixed-wing aircraft was restored to Minas Gerais after the catapult from the decommissioned Veinticinco de Mayo was acquired and installed. In 1997, Minas Gerais was loaned an A-4Q airframe by the Argentine Aviación Naval (Naval Aviation) for deck-handling and interface trials. This was in lead-up to the 1999 acquisition of 20 A-4KU Skyhawks and three TA-4KU trainer aircraft from the Kuwait Air Force for US$70 million. This was the first time since the carrier's commissioning that Força Aeronaval da Marinha (Brazilian Navy Aviation) had been permitted to own and operate fixed-wing aircraft. The 23 aircraft were formed as the First Intercept and Attack Squadron, had all entered service by early 2000, and began carrier operations in late October 2000. In order to operate the new fighters, Minas Gerais underwent a major refit at the Arsenal de Marinha do Rio de Janeiro. The main purpose of this refit was to upgrade the catapult to launch Skyhawks.

Replacement and decommissioning

The replacement of Minas Gerais was first suggested in the early 1980s, as part of planned 15-year naval expansion program. Two different carrier designs were proposed. The first was for a 40,000-ton ship equipped with up to forty aircraft, including naval fighters. To complement this proposal, a plan to expand the Brazilian fleet air arm by acquiring second-hand A-4 Skyhawks from Kuwait or Israel was submitted. For this to happen, the 1965 ruling that prevented the MB from operating fixed-wing aircraft had to be overturned; a decision the FAB opposed. To make the purchase worthwhile, Minas Gerais would have to operate the aircraft until the replacement carrier entered service, which in turn required the installation of a modified steam catapult and arresting gear. As the ship had just emerged from a modernisation refit, this was an expensive proposition, and the Skyhawk acquisition plan was cancelled in October 1984. The Skyhawk plan was successfully revisited in the late 1990s. The second proposal was for a 25,000-ton helicopter carrier built to commercial standards. Later interpretations of this proposal suggested a ship similar to the Royal Navy's HMS Ocean (L12).

Replacement of Minas Gerais was under serious consideration by 1999; despite numerous refits and life-extending upgrades, the MB predicted that the carrier would require replacement before 2010. As well as the two proposals, consideration was given to acquiring a second-hand carrier, such as the French Navy's FRENCH AIRCRAFT CARRIER Foch. One of the main issues in considering the replacement was the MB's significant investment in fixed-wing aviation in the late 1990s; a carrier capable of operating the recently acquired Skyhawks would be more expensive to acquire and operate than a STOVL or helicopter carrier, but the cheaper concepts would require the refactoring of Brazilian naval aviation. In the end, Foch was acquired, renamed NAe São Paulo, and slated to commission into the Marinha do Brasil in April 2001. She was downclassed as a helicopter support ship in 2001 before her decommissioning.

Minas Gerais was decommissioned on 16 October 2001: the second to last of the World War II-era light aircraft carriers to leave service, with the other being the 1959-commissioned INS Viraat (R22) (former HMS Hermes (R12)) which was ordered during the war but not completed and was the oldest aircraft carrier still in service in the world until it was decommissioned in 2017. At the time of her decommissioning, she was the second oldest active aircraft carrier in the world (a title passed on to the 1961-commissioned USS Kitty Hawk (CV-63)). Also at the decommissioning ceremony was 87-year-old Admiral Hélio Leôncio Martins, who was the first commander of the aircraft carrier. There were also crew who had served on the Minas Gerais at different times. The carrier was marked for sale in 2002, and was sought after by British naval associations for return to the United Kingdom and preservation as a museum ship, although they were unable to raise the required money. Just before Christmas 2003, the carrier was listed for sale on auction website eBay by a user claiming to be a shipbroker representing the owner. Bidding reached £4 million before the auction was removed from the website under rules preventing the sale of military ordnance. An auction in Rio de Janeiro in February 2004 also failed to sell the ship. Sometime between February and July 2004, the carrier was towed to the ship breaking yards at Alang, India for dismantling.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Brazilian aircraft carrier Minas Gerais


text:
Original Free Will Baptist Convention

The Original Free Will Baptist Convention is a North Carolina–based body of Free Will Baptists that split from the National Association of Free Will Baptists in 1961.

The Original Free Will Baptist State Convention was established in 1913. In 1935 the State Convention became a charter member of the National Association. The North Carolina convention had developed along lines with slightly different polity from the midwestern and northern Free Will Baptists. They held to a more connectional form of government, and believed the annual conference could settle disputes in and discipline a local church. This view, different educational philosophies, and the desire of the North Carolina convention to operate its own press and Sunday School publishing created tensions that ended in division. The majority of Free Will Baptist churches in North Carolina withdrew from the National Association, while a minority withdrew from the State Convention to maintain affiliation with the National Association.

Headquarters of the State Convention are in Mount Olive, North Carolina. The Convention sponsors the Free Will Baptist Children's Home, Inc. in Middlesex, North Carolina (established 1920), the University of Mount Olive in Mount Olive, North Carolina (chartered 1951), and operates the Free Will Baptist Press in Ayden. It supports foreign missionaries in Bulgaria, India, Mexico, Nepal, Liberia, and the Philippines.

In 1991 they reported over 33,000 members in 236 churches that were organized into 7 conferences. Currently (2003) the Convention has grown to about 250 churches. Most of the churches are in eastern North Carolina.

title: Original Free Will Baptist Convention


text:
Sleeping barber problem

In computer science, the sleeping barber problem is a classic inter-process communication and synchronization problem that illustrates the complexities that arise when there are multiple operating system processes.

The problem was originally proposed in 1965 by computer science pioneer Edsger Dijkstra, who used it to make the point that general semaphores are often superfluous.

Problem statement
Imagine a hypothetical barbershop with one barber, one barber chair, and a waiting room with n chairs (n may be 0) for waiting customers. The following rules apply:
 * If there are no customers, the barber falls asleep in the chair
 * A customer must wake the barber if he is asleep
 * If a customer arrives while the barber is working, the customer leaves if all chairs are occupied and sits in an empty chair if it's available
 * When the barber finishes a haircut, he inspects the waiting room to see if there are any waiting customers and falls asleep if there are none

There are two main complications. First, there is a risk that a race condition, where the barber sleeps while a customer waits for the barber to get them for a haircut, arises because all of the actions—checking the waiting room, entering the shop, taking a waiting room chair—take a certain amount of time. Specifically, a customer may arrive to find the barber cutting hair so they return to the waiting room to take a seat but while walking back to the waiting room the barber finishes the haircut and goes to the waiting room, which he finds empty (because the customer walks slowly or went to the restroom) and thus goes to sleep in the barber chair. Second, another problem may occur when two customers arrive at the same time when there is only one empty seat in the waiting room and both try to sit in the single chair; only the first person to get to the chair will be able to sit.

A multiple sleeping barbers problem has the additional complexity of coordinating several barbers among the waiting customers.

Solutions
There are several possible solutions, but all solutions require a mutex, which ensures that only one of the participants can change state at once. The barber must acquire the room status mutex before checking for customers and release it when they begin either to sleep or cut hair; a customer must acquire it before entering the shop and release it once they are sitting in a waiting room or barber chair, and also when they leave the shop because no seats were available. This would take care of both of the problems mentioned above. A number of semaphores is also required to indicate the state of the system. For example, one might store the number of people in the waiting room.

Implementation
The following pseudocode guarantees synchronization between barber and customer and is deadlock free, but may lead to starvation of a customer. The problem of starvation can be solved with a first-in first-out (FIFO) queue. The semaphore would provide two functions:  and , which in terms of C code would correspond to   and  , respectively.

title: Sleeping barber problem


text:
Talk:List of mechanical engineers

Inclusion criteria? (early comments)
There are several people listed on this page who are clearly not mechanical engineers.
 * I'm removing a couple of people that are not notable WP:NN. -- Alphachimp   talk  05:11, 5 May 2006 (UTC)

 * What is the definition that governs whether someone should be on this page. obviously they have to be an engineer, I would have said that a listee needs to have a wiki page at the very least. Greglocock 20:33, 9 January 2007 (UTC)

 * I have removed a few names from this list as their description on this list mentions another occupation. I am not saying they should not be listed but just not here. Keelback (talk) 14:24, 9 February 2018 (UTC)

Red links
If you add an entry here that does not have a wiki page the link will show up as red. I will remove it in line with wiki policy for lists. So if you want to put someone on this list create the article for the first. Greglocock (talk) 23:06, 23 November 2007 (UTC)

Conru
Conru does not have his own web page, his company does. He has a mechanical engineering degree. Does he belong on this list?

Andrew ConruABC News Founder of Adult FriendFinder, an entrepreneur with a doctorate in mechanical engineering design

Greg Locock (talk) 23:38, 21 October 2008 (UTC)

General cleanup
Re the "this is a mess" note I found when I first stumbled onto this page, I've tried to make some improvements. But I know it is still far from perfect. But, hopefully, it is no longer "a mess". There are still several heritage entries that I think should be deleted (notable in that they don't have birth/death dates), but I'll leave that for others. Plus I'm sure I've left out lots of important individuals. I have also included some individuals who may be more rightly termed "inventors" than "mechanical engineers". But if they have made notable contributions, I've erred on the side of inclusiveness given the "have practiced in" verbiage at the introduction to the page. But I would certainly have no quarrel with anyone who feels they should be deleted. Cheers, --JuniperisCommunis (talk) 16:23, 15 March 2009 (UTC)

What is the purpose of this article?
What is the focus of this article? It appears to be for people who are famous for their work in mechanical engineering? Or are they mechanical engineers who are famous in some way, not necessarily connected with mechanical engineering?

Several entrants appear to be mechanical engineers who are famous for something else such as: Boris Vian - writer Alan Kulwicki - 1992 NASCAR Champion

I question why they should be listed here. Elsewhere under writer or racing driver or whatever but NOT here surely.

Can’t have it both ways surely as many entries such as Leonardo da Vinci only comply with my first definition! Keelback (talk) 06:40, 15 November 2010 (UTC)

 * The lede states: "This is a list of mechanical engineers, notable people who were trained in or practiced mechanical engineering..." (my emphasis).
 * According to their articles, Vian was ['merely'] employed as an engineer, while Kulwicki gained a BSc in mech eng and this knowledge has been cited as a factor of his success as a racecar driver. I can't see any reason for retaining Vian, except for the inclusivity of the lede. As for Kulwicki, I haven't read enough of his article to decide. I am leaning towards the lede being changed so that it is not enough to be 'just' a mechanical engineer, or 'just' having a relevant degree. Really this article wants to list those notable for their involvement with mechanical engineering, which would probably then include many other inventors...
 * EdJogg (talk) 09:37, 15 November 2010 (UTC)

 * I sort of agree. Let's start out by defining who we don't want. eg (a) crackpot inventors (b) PhD engineers who have done little else but publish their theses (c) people who did engineering at uni but made no particular use of that in an engineering field. And who do we want? (1) famous (ie notable) mechanical engineers Greglocock (talk) 00:14, 16 November 2010 (UTC)

 * I did some quick cleanup of the lead per WP:LIST. Per guidelines the list lead paragraph should contain criteria for inclusion. The word "notable" is not considered a sufficient criteria - everyone in Wikipedia is notable. Lacking a def I have made one up that gives some rational to the list, "noted for their contribution to the field". This would mean the person's article references some significant contribution and it is mentioned in the lead. Fountains of Bryn Mawr (talk) 15:11, 22 April 2015 (UTC)

title: Talk:List of mechanical engineers


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The East Is Red (song)

"The East Is Red" is a Chinese Communist Party revolutionary song that was the de facto national anthem of the People's Republic of China during the Cultural Revolution in the 1960s. The lyrics of the song were attributed to Li Youyuan (李有源), a farmer from Shaanbei (northern Shaanxi province), and the melody was derived from a local peasant love song from the Loess Plateau entitled "Bai Ma Diao" 《白马调》 (White Horse Tune), also known as "Zhima You" 《芝麻油》 (Sesame Oil), which was widely circulated in the area around Yan'an in the 1930s. The farmer allegedly got his inspiration upon seeing the rising sun in the morning of a sunny day.

Early history
The lyrics to "The East Is Red" were adapted from an old Shaanxi folk song about love. The lyrics were often changed depending on the singer. The modern lyrics (attributed to Li Youyuan, a farmer from northern Shaanxi) were produced in 1942 during the Second Sino-Japanese War. It is possible that there was an earlier version that referenced Liu Zhidan (a local communist hero), who was killed in Shanxi in 1936. Later, Mao's name replaced Liu's in the lyrics. The song was popular in the Communist base-area of Yan'an, but became less popular after the Chinese Communist Party (CCP) won the Chinese Civil War and established the People's Republic of China in 1949, possibly because some senior CCP leaders disagreed with the song's portrayal of Mao Zedong as "China's savior".

The lyrics of "The East Is Red" idealize Mao Zedong, and Mao's popularization of "The East Is Red" was one of his earliest efforts to promote his image as a perfect hero in Chinese popular culture after the Korean War. In 1956, a political commissar suggested to China's defense minister, Peng Dehuai, that the song be taught to Chinese troops, but Peng opposed Mao's propaganda, saying "That is a personality cult! That is idealism!" Peng's opposition to "The East Is Red", and to Mao's incipient personality cult in general, contributed to Mao purging Peng in 1959. After Peng was purged, Mao accelerated his efforts to build his personality cult; by 1966, he succeeded in having "The East Is Red" sung in place of China's national anthem in an unofficial capacity.

In 1964, Zhou Enlai used "The East Is Red" as the central chorus for a play he created to promote the personality cult of Mao Zedong, with "March Forward under the Banner of Mao Zedong Thought" as the original title. Zhou also served as co-producer, head writer and director of the play. The central theme of the play was that Mao was the only person capable of leading the CCP to victory. The play was performed by 2,000 artists, and was accompanied by a 1,000-strong chorus and orchestra. It was staged repeatedly in Beijing at the Great Hall of the People in order to ensure that all residents would be able to see it (this was in time for the 15th National Day of the People's Republic of China), and was later adapted into a feature film, also titled "The East Is Red," that was shown all over China. It was in this play that the definite version of the song was heard for the first time; this would be the version used in events during the Cultural Revolution until 1969.

During the Cultural Revolution, Tian Han, the author of China's official national anthem, "March of the Volunteers", was purged; as a result, that song was rarely used. "The East Is Red" was used as China's unofficial national anthem during this time. The song was played through PA systems in towns and villages across China at dawn and at dusk. The Custom House on the Bund in Shanghai still plays the song in place of the Westminster Chimes that were originally played by the British. The Central People's Broadcasting Station began broadcasts every day by playing the song on a set of bronze bells that had been cast over 2,000 years earlier during the Warring States period. Radio and television broadcasts nationwide usually began with the song "The East Is Red" in the morning or at early evening, and ended with the song "The Internationale". In 1967, the commune (now township) of Ujme in Akto County, Kizilsu, Xinjiang was renamed Dongfanghong Commune (literally "The East Is Red Commune": ).

Students were obliged to sing the song in unison every morning at the beginning of the first class of the day. In 1969, the tune was used in the Yellow River Piano Concerto. The Concerto was produced by Jiang Qing and adapted from the Yellow River Cantata by Xian Xinghai. When she adapted the Cantata, Jiang added the tune to "The East Is Red" in order to connect the Concerto with the themes of the Cultural Revolution. After China launched its first satellite in 1970, "The East Is Red" was the first signal the craft sent back to Earth. However, that same year, the status of "The East Is Red" as the unofficial national anthem was relinquished; beginning on October 1 of that year, the current official national anthem,  March of the Volunteers, was readopted and played (albeit only in its instrumental version) once again in all national events.

Modern China
Because of its associations with the Cultural Revolution, the song was rarely heard after the rise of Deng Xiaoping in the late 1970s. To this day, the song is considered by some in China to be a somewhat unseemly reminder of the cult of personality associated with Mao. Its official use has largely been replaced by the "March of the Volunteers", whose lyrics mention neither the CCP nor Mao. "The East Is Red" is still commonly heard in recordings played by electronic cigarette lighters bearing Mao's face that are popular with tourists.

The tune of "The East Is Red" remains popular in Chinese popular culture. In 2009, it was voted as the most popular patriotic song in a Chinese government-run internet poll. It is used as the belling melody for striking clocks like Beijing railway station and the Beijing Telegraph Building, Shanghai Customs House as well as the Drum Tower in Xi'an.

Some radio stations in China have used "The East Is Red" as an interval signal, including China Radio International (Indonesian service) and Xinjiang People's Radio Station.

title: The East Is Red (song)


text:
User:Vanulor

A username which I gathered from the Wolf of Winter.

title: User:Vanulor


text:
Dihedral (aeronautics)

In aeronautics, dihedral is the angle between the left and right wings (or tail surfaces) of an aircraft. "Dihedral" is also used to describe the effect of sideslip on the rolling of the aircraft.

Dihedral angle is the upward angle from horizontal of the wings or tailplane of a fixed-wing aircraft. "Anhedral angle" is the name given to negative dihedral angle, that is, when there is a downward angle from horizontal of the wings or tailplane of a fixed-wing aircraft.

Dihedral angle has a strong influence on dihedral effect, which is named after it. Dihedral effect is the amount of roll moment produced in proportion to the amount of sideslip. Dihedral effect is a critical factor in the stability of an aircraft about the roll axis (the spiral mode). It is also pertinent to the nature of an aircraft's Dutch roll oscillation and to maneuverability about the roll axis.

Longitudinal dihedral is a comparatively obscure term related to the pitch axis of an airplane. It is the angle between the zero-lift axis of the wing and the zero-lift axis of the horizontal tail. Longitudinal dihedral can influence the nature of controllability about the pitch axis and the nature of an aircraft's phugoid-mode oscillation.

When the term "dihedral" (of an aircraft) is used by itself it is usually intended to mean "dihedral angle". However, context may otherwise indicate that "dihedral effect" is the intended meaning.

Dihedral angle vs. dihedral effect
Dihedral angle is the upward angle from horizontal of the wings of a fixed-wing aircraft, or of any paired nominally-horizontal surfaces on any aircraft. The term can also apply to the wings of a bird. Dihedral angle is also used in some types of kites such as box kites. Wings with more than one angle change along the full span are said to be polyhedral.

Dihedral angle has important stabilizing effects on flying bodies because it has a strong influence on the dihedral effect.

Dihedral effect of an aircraft is a rolling moment resulting from the vehicle having a non-zero angle of sideslip. Increasing the dihedral angle of an aircraft increases the dihedral effect on it. However, many other aircraft parameters also have a strong influence on dihedral effect. Some of these important factors are: wing sweep, vertical center of gravity, and the height and size of anything on an aircraft that changes its sidewards force as sideslip changes.

Longitudinal dihedral
Dihedral angle on an aircraft almost always implies the angle between two paired surfaces, one on each side of the aircraft. Even then, it is almost always between the left and right wings. However, mathematically dihedral means the angle between any two planes. So, in aeronautics, in one case, the term "dihedral" is applied to mean the difference in angles between two front-to-back surfaces:

Longitudinal dihedral is the difference between the angle of incidence of the wing root chord and angle of incidence of the horizontal tail root chord.

Longitudinal dihedral can also mean the angle between the zero-lift axis of the wing and the zero-lift axis of the horizontal tail instead of between the root chords of the two surfaces. This is the more meaningful usage because the directions of zero-lift are pertinent to trim and stability while the directions of the root chords are not.

This measurement is also often referred to as decalage.

History
In geometry, dihedral angle is the angle between two planes. Aviation usage differs slightly from usage in geometry. In aviation, the usage "dihedral" evolved to mean the positive, up angle between the left and right wings, while usage with the prefix "an-" (as in "anhedral") evolved to mean the negative, down angle between the wings.

The aerodynamic stabilizing qualities of a dihedral angle were described in an influential 1810 article by Sir George Cayley.

Aircraft stability analysis
In analysis of aircraft stability, the dihedral effect is also a stability derivative called Cl $\beta$  meaning the change in rolling moment coefficient (the "Cl") per degree (or radian) of change in sideslip angle (the "$$\beta$$").

Provision of stability
The purpose of dihedral effect is to contribute to stability in the roll axis. It is an important factor in the stability of the spiral mode which is sometimes called "roll stability". The dihedral effect does not contribute directly to the restoring of "wings level", but it indirectly helps restore "wings level" through its effect on the spiral mode of motion described below.

Wing clearance
Aircraft designers may increase dihedral angle to provide greater clearance between the wing tips and the runway. This is of particular concern with swept-wing aircraft, whose wingtips could hit the runway on rotation/touchdown. In military aircraft dihedral angle space may be used for mounting materiel and drop-tanks on wing hard points, especially in aircraft with low wings. The increased dihedral effect caused by this design choice may need to be compensated for, perhaps by decreasing the dihedral angle on the horizontal tail.

Using dihedral angle to adjust dihedral effect
During design of a fixed-wing aircraft (or any aircraft with horizontal surfaces), changing dihedral angle is usually a relatively simple way to adjust the overall dihedral effect. This is to compensate for other design elements' influence on the dihedral effect. These other elements (such as wing sweep, vertical mount point of the wing, etc.) may be more difficult to change than the dihedral angle. As a result, differing amounts of dihedral angle can be found on different types of fixed-wing aircraft. For example, the dihedral angle is usually greater on low-wing aircraft than on otherwise-similar high-wing aircraft. This is because "highness" of a wing (or "lowness" of vertical center of gravity compared to the wing) naturally creates more dihedral effect itself. This makes it so less dihedral angle is needed to get the amount of dihedral effect needed.

Common confusions
Dihedral effect is defined simply to be the rolling moment caused by sideslip and nothing else. Rolling moments caused by other things that may be related to sideslip have different names.

Dihedral effect is not caused by yaw rate, nor by the rate of sideslip change. Since dihedral effect is noticed by pilots when "rudder is applied", many pilots and other near-experts explain that the rolling moment is caused by one wing moving more quickly through the air and one wing less quickly. Indeed, these are actual effects, but they are not the dihedral effect, which is caused by being at a sideslip angle, not by getting to one. These other effects are called "rolling moment due to yaw rate" and "rolling moment due to sideslip rate" respectively.

Dihedral effect is not roll stability in and of itself. Roll stability is less-ambiguously termed "spiral mode stability" and dihedral effect is a contributing factor to it.

How dihedral angle creates dihedral effect and stabilizes the spiral mode
The dihedral angle contributes to the total dihedral effect of the aircraft. In turn, the dihedral effect contributes to stability of the spiral mode. A stable spiral mode will cause the aircraft to eventually return to a nominally "wings level" bank angle when the angle of the wings is disturbed to become off-level.

If a disturbance causes an aircraft to roll away from its normal wings-level position as in Figure 1, the aircraft will begin to move somewhat sideways toward the lower wing. In Figure 2, the airplane's flight path has started to move toward its left while the nose of the airplane is still pointing in the original direction. This means that the oncoming air is arriving somewhat from the left of the nose. The airplane now has sideslip angle in addition to the bank angle. Figure 2 shows the airplane as it presents itself to the oncoming air.

How dihedral angle creates rolling moment from sideslip (dihedral effect)
In Figure 2, the sideslip conditions produce greater angle of attack on the forward-yawed wing and smaller angle of attack on the rearward-yawed wing. This alteration of angle of attack by sideslip is visible in Figure 2. As greater angle of attack produces more lift (in the usual case, when the wing is not near stalling), the forward wing will have more lift and the rearward wing will have less lift. This difference in lift between the wings is a rolling moment, and it is caused by the sideslip. It is a contribution to the total dihedral effect of the aircraft.

How dihedral effect stabilizes the spiral mode
The rolling moment created by the sideslip (labeled as "P") tends to roll the aircraft back to wings level. More dihedral effect tries to roll the wings in the "leveling" direction more strongly, and less dihedral effect tries to roll the wings in the "leveling" direction less strongly. Dihedral effect helps stabilize the spiral mode by tending to roll the wings toward level in proportion to the amount of sideslip that builds up. It is not the whole picture however. At the same time that angle of sideslip is building up, the vertical fin is trying to turn the nose back into the wind, much like a weathervane, minimizing the amount of sideslip that can be present. If there is no sideslip, there can be no restoring rolling moment. If there is less sideslip, there is less restoring rolling moment. Yaw stability created by the vertical fin opposes the tendency for dihedral effect to roll the wings back level by limiting sideslip.

The spiral mode is the tendency to slowly diverge from, or the tendency to slowly return to wings level. If the spiral mode is stable, the aircraft will slowly return to wings-level, if it is unstable, the aircraft will slowly diverge from wings-level. Dihedral effect and yaw stability are the two primary factors that affect the stability of the spiral mode, although there are other factors that affect it less strongly.

Other factors contributing to dihedral effect
Factors of design other than dihedral angle also contribute to dihedral effect. Each increases or decreases total aircraft dihedral effect to a greater or lesser degree.

Sweepback
Wing sweepback also increases the dihedral effect, for roughly 1° of effective dihedral with every 10° of sweepback. This is one reason for anhedral configuration on aircraft with high sweep angle, as well as on some airliners, even on low-wing aircraft such as the Tu-134 and Tu-154.

In any case, wing sweepback can also occur with a dihedral configuration. For instance, two small biplanes produced from the 1930s to 1945 by Bücker Flugzeugbau in Germany, the Bücker Jungmann two-seat trainer and the Bücker Jungmeister aerobatic competition biplane, were designed with sweepbacks of approximately 11 degrees, which provided significant dihedral effect – in addition to their small dihedral angles having a similar but lesser effect.

Vertical position of the center of mass
The center of mass, usually called the center of gravity or "CG", is the balance point of an aircraft. If suspended at this point and allowed to rotate, a body (aircraft) will be balanced. The front-to-back location of the CG is of primary importance for the general stability of the aircraft, but the vertical location has important effects as well.

The vertical location of the CG changes the amount of dihedral effect. As the "vertical CG" moves lower, dihedral effect increases. This is caused by the center of lift and drag being further above the CG and having a longer moment arm. So, the same forces that change as sideslip changes (primarily sideforce, but also lift and drag) produce a larger moment about the CG of the aircraft. This is sometimes referred to as the pendulum effect.

An extreme example of the effect of vertical CG on dihedral effect is a paraglider. The dihedral effect created by the very low vertical CG more than compensates for the negative dihedral effect created by the strong anhedral of the necessarily strongly downward curving wing.

Wing location
The wing location on a fixed-wing aircraft will also influence its dihedral effect. A high-wing configuration provides about 5° of effective dihedral over a low-wing configuration.

Effects of too much dihedral effect
A side effect of too much dihedral effect, caused by excessive dihedral angle among other things, can be yaw-roll coupling (a tendency for an aircraft to Dutch roll). This can be unpleasant to experience, or in extreme conditions it can lead to loss of control or can overstress an aircraft.

Anhedral

Military fighter aircraft often have near zero or even anhedral angle reducing dihedral effect and hence reducing the stability of the spiral mode. This increases maneuverability which is desirable in fighter-type aircraft.

Anhedral angles are also seen on aircraft with a high mounted wing, such as the very large Antonov An-124 and Lockheed C-5 Galaxy cargo aircraft. In such designs, the high mounted wing is above the aircraft's center of gravity which confers extra dihedral effect due to the pendulum effect (also called the keel effect) and so additional dihedral angle is often not required. Such designs can have excessive dihedral effect and so be excessively stable in the spiral mode, so anhedral angle on the wing is added to cancel out some of the dihedral effect so that the aircraft can be more easily maneuvered.

Polyhedral
Most aircraft have been designed with planar wings with simple dihedral (or anhedral). Some older aircraft such as the Beriev Be-12 were designed with gull wings bent near the root. Others, such as the Vought F4U Corsair, used an inverted gull wing design, which allowed for shorter landing struts and extra ground clearance for large propellers and external payloads, such as external fuel tanks or bombs. Modern polyhedral wing designs generally bend upwards near the wingtips (also known as tip dihedral), increasing dihedral effect without increasing the angle the wings meet at the root, which may be restricted to meet other design criteria.

Polyhedral is seen on gliders and some other aircraft. The McDonnell Douglas F-4 Phantom II is one such example, unique among jet fighters for having dihedral wingtips. This was added after flight testing of the flat winged prototype showed the need to correct some unanticipated spiral mode instability – angling the wingtips, which were already designed to fold up for carrier operations, was a more practical solution than re-engineering the entire wing.

title: Dihedral (aeronautics)


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38 (number)

38 (thirty-eight) is the natural number following 37 and preceding 39.

In mathematics

 * specifically, the 11th discrete Semiprime, it being the 7th of the form (2.q).
 * the first member of the third cluster of two discrete semiprimes 38, 39 the next such cluster is 57, 58.
 * with an aliquot sum of 22 in an aliquot sequence of five composite numbers (38,22,14,10,8,7,1,0) to the Prime in the 7-aliquot tree. 34 is the first semiprime within a chain  of 4 semiprimes in its aliquot sequence (38,22,14,10). The next semiprime with a four semiprime chain is 166.
 * 38! − 1 yields $523,022,617,466,601,100,000,000,000,000,000,000,000,000,000$ which is the 16th factorial prime.
 * There is no answer to the equation φ(x) = 38, making 38 a nontotient.
 * 38 is the sum of the squares of the first three primes.
 * 37 and 38 are the first pair of consecutive positive integers not divisible by any of their digits.
 * 38 is the largest even number which cannot be written as the sum of two odd composite numbers.
 * The sum of each row of the only non-trivial (order 3) magic hexagon is 38.

In science

 * The atomic number of strontium

Astronomy

 * The Messier object M38, a magnitude 7.0 open cluster in the constellation Auriga
 * The New General Catalogue object NGC 38, a spiral galaxy in the constellation Pisces

In other fields
Thirty-eight is also:
 * The 38th parallel north is the pre-Korean War boundary between North Korea and South Korea.
 * The number of slots on an American roulette wheel (0, 00, and 1 through 36; European roulette does not use the 00 slot and has only 37 slots)
 * The Ishihara test is a color vision test consisting of 38 pseudoisochromatic plates.
 * A "38" is often the name for a snub nose .38 caliber revolver.
 * The 38 class is the most famous class of steam locomotive used in New South Wales
 * Gerald Ford, 38th President of the United States
 * Arnold Schwarzenegger, 38th Governor of California, most recent Republican governor of California, and the second governor to be born outside of the United States
 * Cats have a total of 38 chromosomes in their genome.
 * Number used by Zane Smith and Front Row Motorsports to win the 2022 NASCAR Camping World Truck Series championship.
 * The Lucky 38, the casino from Fallout: New Vegas.

title: 38 (number)


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Robert Downey Sr.

Robert John Downey Sr. ( Elias Jr.; June 24, 1936 – July 7, 2021) was an American film director, screenwriter and actor. He was known for writing and directing his underground film Putney Swope (1969), a satire on the New York Madison Avenue advertising world. According to film scholar Wheeler Winston Dixon, Downey's films during the 1960s were "strictly take-no-prisoners affairs, with minimal budgets and outrageous satire, effectively pushing forward the countercultural agenda of the day." He was the father of American actor Robert Downey Jr.

Early life
Robert John Downey Sr. was born Robert John Elias Jr. in the Manhattan borough of New York City, on June 24, 1936. He was the son of Elizabeth "Betty" McLauchlen, a model and magazine editor, and Robert John Elias Sr., who worked in management of motels and restaurants. His paternal grandparents were Lithuanian Jews, while his mother was of half Hungarian Jewish and half Irish ancestry. He grew up in Rockville Centre, New York. He changed his surname to Downey after his stepfather, when he wanted to enlist in the United States Army while being underage. Downey later said he wrote an unpublished novel during his time in the army, though he spent much of his military career "in the stockade".

Career
Downey initially made his mark creating very low-budget independent films aligning with the absurdist movement, in line with counterculture, anti-establishment, 1960s America. His work in the late 1960s and 1970s was quintessential anti-establishment, reflecting the nonconformity popularized by larger counterculture movements and given impetus by new freedoms in films, such as the breakdown of codes on censorship. In keeping with the underground tradition, his 1970s films were independently made on shoestring budgets and were relatively obscure in the Absurdist movement, finding cult notoriety.

In 1961, working with film editor Fred von Bernewitz, Downey began writing and directing low-budget 16mm films that gained an underground following, beginning with Ball's Bluff (1961), a fantasy short about a Civil War soldier who awakens in Central Park in 1961. He moved into big-budget filmmaking with the surrealistic Greaser's Palace (1972). His last film was Rittenhouse Square (2005), a documentary capturing life in a Philadelphia park.

Downey's films were often family affairs. His first wife appears in four of his films (Chafed Elbows, Pound, Greaser's Palace, Moment to Moment), as well as co-writing one (Moment to Moment). Daughter Allyson and son Robert Downey Jr. each made their film debuts in the 1970 absurdist comedy Pound at the ages of 7 and 5, respectively; Allyson would appear in one more film by her father, Up the Academy. Robert Jr.'s lengthy acting résumé includes appearances in eight films directed by his father (Pound, Greaser's Palace, Moment to Moment, Up the Academy, America, Rented Lips, Too Much Sun, Hugo Pool), as well as two acting appearances in movies where his father was also an actor (Johnny Be Good, Hail Caesar).

Personal life and death
Downey was married three times. His first marriage was to actress Elsie Ann Ford (1934–2014) in 1962, with whom he had two children: actress-writer Allyson (b. 1963) and actor Robert Jr. (b. 1965). The marriage ended in divorce in 1975. His second marriage, to actress-writer Laura Ernst, lasted until her death on January 27, 1994, from amyotrophic lateral sclerosis. In 1998, he married his third wife, Rosemary Rogers, humorist and co-author of Saints Preserve Us! and other books. They lived in New York City. Downey died of complications from Parkinson's disease in his sleep at his home in Manhattan, on July 7, 2021, thirteen days after his 85th birthday.

Legacy
The Criterion Collection released five of his films (the National Film Registry inductee Putney Swope, Babo 73, Chafed Elbows, No More Excuses and Taos Tonight) as part of the Eclipse Series. A 2022 documentary film simply called "Sr." was made by Chris Smith of American Movie fame and was produced by his son. It won the National Board of Review Award for Best Documentary Feature.

title: Robert Downey Sr.


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Anhedral

Anhedral may refer to:

 * Anhedral angle, the downward angle from horizontal of the wings or tailplane of a fixed-wing aircraft
 * Anhedral (petrology), a rock texture without crystal faces or cross-section shape in thin section

title: Anhedral