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Talk:Camp David

Location
From the wiki article:

Catoctin Mountain Park does not indicate the location of Camp David on its official park maps due to privacy and security concerns.

It can easily be found on Google Maps, heck, Camp David is just off Park Central Rd. — Preceding unsigned comment added by 206.188.64.244 (talk) 22:16, 23 November 2013 (UTC)

Untitled
From http://www.nps.gov/disclaimer.htm : "Information presented on this website, unless otherwise indicated, is considered in the public domain."

From Mount Vernon to Crawford
We might need to use the book From Mount Vernon to Crawford by Kenneth Walsh for this article, as it could use some sources, even if largely from an NPS site.--Bedford 04:41, 5 September 2007 (UTC)

Possible Copyright Violation
A great deal of content is taken verbatim from an article located at the Federation of American Scientists site at http://www.fas.org/nuke/guide/usa/c3i/campdavid.htm. There is nothing noting that the material is in the public domain on that page, and the main site of the FAS states, ALL RIGHTS RESERVED. We should look into this to make sure it doesn't violate any copyright rules. RobHoitt 00:31, 8 September 2007 (UTC)

 * Just to be safe, I checked the NPS website, very little of the content here seems to be derived from that page http://www.nps.gov/cato/. RobHoitt 00:39, 8 September 2007 (UTC)
 * As per the instructions on WP:CV, it is possible to revert to a non-copyrighted version, but it dates back to a stub at 06:47, 12 December 2001 (UTC). Realistically, I can still preserve the gallery and links sections. Zzyzx11 (Talk) 00:18, 16 September 2007 (UTC)
 * The Establishment section and Post World War II era and Modern era all seem to come from here. Some of the FAS material seems to come from here (the old Clinton whitehouse.gov site). FAS largely republishes material from other sources, so finding something on FAS without a credit is a tipoff that another source should be sought. I'd rather we wrote our own article but I think there is no copyright issue here; do others agree? --Dhartung | Talk 01:17, 16 September 2007 (UTC)
 * I guess the ounce of prevention is worth a pound of cure. I think Zzyzz11 did the right thing here. (And I should point out that his user name comes from a way too archaic Zork reference.) Cheers! RobHoitt 00:45, 20 September 2007 (UTC)

Obama at Camp David
Shouldn't this article be updated with news and photos of Barack Obama and his family at Camp David? It seems to concentrate mainly on Bush at the moment. 92.9.92.72 (talk) 17:10, 29 March 2009 (UTC)

Two years later, the question still remains...where are pictures of the current president at Camp David? 203.110.206.180 (talk) 11:41, 17 May 2011 (UTC)

 * Welcome to Wikipedia, the encyclopedia ANYONE can edit. If you think it's missing something, go find it! Every president has used Camp David with varying degrees, President Bush used it quite often so that's why there are many pictures from the Bush era (plus it was 8 years). It seems as though President Obama doesn't use it as much, or at least not to much publicity. --WGFinley (talk) 05:21, 28 January 2012 (UTC)

I went looking tonight and unfortunately there are ZERO Camp David images at whitehouse.gov for President Obama. I have found some Camp David images of him but without sources I am unable to tell if they are government photos (which we can use) or press photos (which we can't). I'll keep an eye out because it would be nice if there was something in the gallery from each president. --WGFinley (talk) 08:04, 28 January 2012 (UTC)

Analaogous Facilities
The Bonnie Doon Reference for the Australian Prime Minister is a spoof as far as I can tell. Kirribilli House is the Sydney Residence of the Prime Minister of Australia. —Preceding unsigned comment added by 203.35.82.133 (talk) 23:37, 21 April 2009 (UTC)

Marine Corps-centric
It seems this article has become more and more about the military (or naval) nature of Camp David. While interesting, it is not exactly on topic. Ought we to do a serious pruning of the article? Paul, in Saudi (talk) 02:51, 3 September 2011 (UTC)
 * I have struck that section, it looks good but appears to be original research as there's not a single source citation in the section. I tried to look for sources for that section and found nothing. Since it's been unsourced for nearly two years I removed the section. --WGFinley (talk) 05:18, 28 January 2012 (UTC)
 * I like it better now without the USMC focus. Paul, in Saudi (talk) 07:34, 28 January 2012 (UTC)

Pictures
I believe the pictures need to be cleaned up. Some of them barely show Camp David at all and just focus on people. In particular, the pictures that only shows a tennis court wall, a door, or a dark, blurry background. EternalFlare (talk) 23:03, 30 January 2013 (UTC)

Seconded! — Preceding unsigned comment added by 2600:8800:301:9B00:414F:D767:8C71:3877 (talk) 17:03, 19 June 2017 (UTC)

 * This website < https://whitehouse.gov1.info/camp-david/ > contains photos. It also includes photos of Presidents' Harry Truman and Donald Trump, both of which seem to be omitted.  Let us eat lettuce (talk) 23:21, 25 August 2017 (UTC)

Presidential Use Section
I noticed when adding a citation for the Bill Clinton post that most of the bullet points in this section have been pulled verbatim from source number 14 in the 'References' section. I updated the Bill Clinton point, but it might be a good idea to update the others as well. --Alwhela1 (talk) 05:56, 12 February 2018 (UTC)

The entry for Trump brings up spending time at his properties at tax payers expense. While accurate, this does not seem to fit the general feel of this section as that does not pertain to Camp David. Additionally, the way it is written comes across as editorialized. The entries for other presidents do not mention the other places that they preferred to go to. Consider removing non-Camp David material or re-writing section.Butch81385 (talk) 15:09, 17 July 2018 (UTC)

I have already changed the Presidential Use chart for Trump from "2" to "N/A" once. Why has it been changed back to 2? Where is the citation that says it is 2? That information is definitely not in the book cited for the chart. The total for Trump should be "N/A" unless someone can cite a reputable source. Couchinsurance (talk) 15:03, 5 May 2020 (UTC)

The number for Trump has been changed to "13". As I have pointed out before, the majority of information in the table was pulled from the source listed. However, there are NO data in the book about Trump's visits. The statistic for Trump will need to be sourced elsewhere. As of right now it is not. Where does the 13 come from? If it isn't cited, it should be removed. Couchinsurance (talk) 06:30, 27 June 2020 (UTC)

Who is whose source?
A book that was self-published in 2016 appears to have copied previously unsourced material from this Wikipedia page and later was cited as the source for the same material (p.115). I removed it. I did some editing of the WP page today. The following is the text as it was before then. I bolded the parts that are used in the book.
 * Camp David is the country retreat for the president of the United States. It is located in the wooded hills [about 62 miles north-northwest of Washington, D.C.,] in Catoctin Mountain Park, in Frederick County, Maryland, near the towns of Thurmont, and Emmitsburg, about 62 miles (100 km) north-northwest of the national capital city of Washington, D.C.[1][2][3] It is officially known as the Naval Support Facility Thurmont, because it is technically a military installation, the staffing is primarily provided by the Seabees, Civil Engineer Corps (CEC), and the United States Navy and the United States Marine Corps. Naval construction battalions are tasked with base construction and send detachments as needed.

 * Originally [First] known as Hi-Catoctin, Camp David was built as a camp for federal government agents and their families by the [WBA] Works Progress Administration.[4] Construction started in 1935 and was completed in 1938.[5] In 1942, President Franklin D. Roosevelt converted it to a presidential retreat and renamed it "Shangri-La" (for the fictional Himalayan paradise in the 1933 novel Lost Horizon by British author James Hilton).[4]

 * Camp David received its present name in 1953 from Dwight D. Eisenhower, in honor of his father, and grandson, both named David.[6]

 * The Catoctin Mountain Park does not indicate the location of Camp David on park maps due to privacy and security concerns, although it can be seen through the use of publicly accessible satellite images.

 * Franklin D. Roosevelt hosted Sir Winston Churchill at Camp David in May 1943.[7] Dwight D. Eisenhower held his first cabinet meeting there on November 22, 1955 following hospitalization and convalescence he required after a heart attack suffered in Denver, Colorado on September 24.[8] Eisenhower met there with Nikita Khrushchev for two days of discussions in September 1959.[9][self-published source?]

 * John F. Kennedy and his family often enjoyed riding and other recreational activities there, and Kennedy often allowed White House staff and Cabinet members to use the retreat when he or his family were not there.[9] Lyndon B. Johnson met with advisors in this setting and hosted both Australian prime minister Harold Holt and Canadian prime minister Lester B. Pearson there.[10] Richard Nixon was a frequent visitor. He personally directed the construction of a swimming pool and other improvements to Aspen Lodge.[11] Gerald Ford often rode his snowmobile around Camp David and hosted Indonesian president Suharto there.[12]

 * Jimmy Carter initially favored closing Camp David in order to save money. Once Carter actually visited the place, he decided to keep it.[13] Carter brokered the Camp David Accords there in September 1978 between Egyptian president Anwar al-Sadat and Israeli prime minister Menachem Begin.[7] Ronald Reagan visited the retreat more than any other president.[9] In 1984, Reagan hosted British prime minister Margaret Thatcher.[9] George H. W. Bush's daughter, Dorothy Bush Koch, was married there in 1992, in the first [ever] wedding held at Camp David.[14] During Bill Clinton's time in office, British prime minister Tony Blair was among the many visitors that the president hosted at Camp David.[15][self-published source?] He also held the 2000 Camp David Summit between Israeli prime minister Ehud Barak and Palestinian Authority chairman Yasser Arafat.[16]

 * George W. Bush hosted dignitaries, including President of Russia Vladimir Putin, there in 2003,[17][18] and hosted British prime minister Gordon Brown, in 2007.[19] He also hosted Danish prime minister Anders Fogh Rasmussen in June 2006,[20] and President Musharraf of Pakistan at Camp David.[21] Barack Obama chose Camp David to host the 38th G8 summit in 2012.[22] President Obama also hosted Russian prime minister Dmitry Medvedev at Camp David,[23] as well as the GCC Summit there in 2015.[24]

Space4Time3Continuum2x (talk) 14:15, 16 May 2020 (UTC)

Camp David Practice Golf Facility
President Eisenhower had the famous golf course architect Robert Trent Jones design a par 3 of a maximum 140 yards with four different tees. Ike also had a 250 yard driving range put in.<ref]https://aboutcampdavid.blogspot.com/2010/08/camp-david-golf-course.html </ref] Eisenhower, Kennedy, Nixon, Ford, Bush Sr., Clinton, Bush Jr., Obama, and Trump were/are golfers. 73.85.200.118 (talk) 15:43, 18 May 2020 (UTC)

I understand that presidents played golf but why is there suddenly a HUGE amount of golf-related information on this page? A section discussing the facilities at Camp David for golfing seems fine, but all the various references peppered throughout the page seems terribly slapdash. In my opinion, the references should be removed or at the very least better arranged. Couchinsurance (talk) 20:59, 20 May 2020 (UTC)
 * I agree, and I removed the unsourced ones. Since Eisenhower had the "golf course" built, I left the mention in the lead, and I removed the blog and added a proper source to the golf section. Space4Time3Continuum2x (talk) 21:09, 20 May 2020 (UTC)

code name?
This article states: "It is code named Naval Support Facility Thurmont." Not sure this is a code name (a somewhat melodramatic term often used to make it sound like something sinister, clandestine, or secretive), it is just the official facility name for this USN operated base, consistent with many other support, as opposed to operational, bases around the world. Like most U.S. military bases, these facilities typically are named for a local geographic feature or city unless they get named for some specific historical figure, e.g., NSF Arlington (for Arlington VA) or NSF Dahlgren (for Rear Admiral John Adolphus Dahlgren - also in VA east of Fredericksburg). Thurmont MD (about 3 miles away from the base) is the closest town to Camp David (which if anything, is probably better described as a "code name"). — Preceding unsigned comment added by 2601:801:300:7520:B0DB:1C4F:A8F7:D964 (talk) 19:37, 27 March 2024 (UTC)

title: Talk:Camp David


text:
Commonwealth

A commonwealth is a traditional English term for a political community founded for the common good. The noun "commonwealth", meaning "public welfare, general good or advantage", dates from the 15th century. Originally a phrase (the common-wealth or the common wealth – echoed in the modern synonym "public wealth"), it comes from the old meaning of "wealth", which is "well-being", and is itself a loose translation of the Latin res publica. The term literally meant "common well-being". In the 17th century, the definition of "commonwealth" expanded from its original sense of "public welfare" or "commonweal" to mean "a state in which the supreme power is vested in the people; a republic or democratic state".

The term evolved to become a title to a number of political entities. Three countries – Australia, the Bahamas, and Dominica – have the official title "Commonwealth", as do four U.S. states and two U.S. territories. Since the early 20th century, the term has been used to name some fraternal associations of states, most notably the Commonwealth of Nations, an organisation primarily of former territories of the British Empire. It is also used in the translation for the organisation made up of formerly Soviet states, the Commonwealth of Independent States. Informally, by analogy to the Commonwealth of Nations, the French-influenced post-colonial Organisation internationale de la Francophonie is sometimes referred to in the English language as the "French Commonwealth ", although the organisation itself never uses the term.

Rome
Translations of Ancient Roman writers' works to English have on occasion translated "Res publica", and variants thereof, to "the commonwealth", a term referring to the Roman state as a whole.

England
The Commonwealth of England was the official name of the political unit (de facto military rule in the name of parliamentary supremacy) that replaced the Kingdom of England (after the English Civil War) from 1649–53 and 1659–60, under the rule of Oliver Cromwell and his son and successor Richard. From 1653 to 1659, although still legally known as a Commonwealth, the republic, united with the former Kingdom of Scotland, operated under different institutions (at times as a de facto monarchy) and is known by historians as the Protectorate. In a British context, it is sometimes referred to as the "Old Commonwealth".

In the later 20th century a socialist political party known as the Common Wealth Party was active. Previously a similarly named party, the Commonwealth Land Party, was in existence.

Iceland
The Icelandic Commonwealth or the Icelandic Free State (Þjóðveldið) was the state existing in Iceland between the establishment of the Althing in 930 and the pledge of fealty to the Norwegian king in 1262. It was initially established by a public consisting largely of recent immigrants from Norway who had fled the unification of that country under King Harald Fairhair.

Philippines
The Commonwealth of the Philippines was the administrative body that governed the Philippines from 1935 to 1946, aside from a period of exile in the Second World War from 1942 to 1945 when Japan occupied the country. It replaced the Insular Government, a United States territorial government, and was established by the Tydings–McDuffie Act. The Commonwealth was designed as a transitional administration in preparation for the country's full achievement of independence, which was achieved in 1946. The Commonwealth of the Philippines was a founding member of the United Nations.

Poland–Lithuania
Republic is still an alternative translation of the traditional name Rzeczpospolita of the Polish–Lithuanian Commonwealth. Wincenty Kadłubek (Vincent Kadlubo, 1160–1223) used for the first time the original Latin term res publica in the context of Poland in his "Chronicles of the Kings and Princes of Poland". The name was used officially for the confederal union formed by Poland and Lithuania (1569–1795).

It is also often referred as "Nobles' Commonwealth" (1505–1795, i.e., before the union). In the contemporary political doctrine of the Polish–Lithuanian Commonwealth, "our state is a Republic (or Commonwealth) under the presidency of the King". The Commonwealth introduced a doctrine of religious tolerance called Warsaw Confederation, had its own parliament Sejm (although elections were restricted to nobility and elected kings, who were bound to certain contracts Pacta conventa from the beginning of the reign).

"A commonwealth of good counsaile" was the title of the 1607 English translation of the work of Wawrzyniec Grzymała Goślicki "De optimo senatore" that presented to English readers many of the ideas present in the political system of the Polish–Lithuanian Commonwealth.

Catalonia
Between 1914 and 1925, Catalonia was an autonomous region of Spain. Its government during that time was given the title mancomunidad (Catalan: mancomunitat), which is translated into English as "commonwealth". The Commonwealth of Catalonia had limited powers and was formed as a federation of the four Catalan provinces. A number of Catalan-language institutions were created during its existence.

Liberia
Between 1838 and 1847, Liberia was officially known as the "Commonwealth of Liberia". It changed its name to the "Republic of Liberia" when it declared independence (and adopted a new constitution) in 1847.

Australia
"Commonwealth" was first proposed as a term for a federation of the six Australian crown colonies at the 1891 constitutional convention in Sydney. Its adoption was initially controversial, as it was associated by some with the republicanism of Oliver Cromwell (see above), but it was retained in all subsequent drafts of the constitution. The term was finally incorporated into law in the Commonwealth of Australia Constitution Act 1900, which established the federation. Australia operates under a federal system, in which power is divided between the federal (national) government and the state governments (the successors of the six colonies). So, in an Australian context, the term "Commonwealth" (capitalised), which is often abbreviated to Cth, refers to the federal government, and "Commonwealth of Australia" is the official name of the country.

The Bahamas
The Bahamas, a Commonwealth realm, has used the official style Commonwealth of The Bahamas since its independence in 1973.

Dominica
The small Caribbean republic of Dominica has used the official style Commonwealth of Dominica since 1978.

States
Four states of the United States of America officially designate themselves as "commonwealths". All four were part of Great Britain's possessions along the Atlantic coast of North America prior to the American Revolution. As such, they share a strong influence of English common law in some of their laws and institutions. The four are:
 * Kentucky is designated a commonwealth by the Kentucky Constitution as the "Commonwealth of Kentucky".
 * Massachusetts is a commonwealth, declaring itself as such in its constitution, which states: "[T]he body politic is formed by a voluntary association of individuals: it is a social compact, by which the whole people covenants with each citizen, and each citizen with the whole people, that all shall be governed by certain laws for the common good."
 * Pennsylvania uses the "Commonwealth of Pennsylvania" constitutionally and in its official title.
 * Virginia has been known as the "Commonwealth of Virginia" since before the American Revolutionary War, and is referred to as a commonwealth in its constitution.

Territories
Two organized but unincorporated U.S. territories are called commonwealths. The two are:
 * Commonwealth of Puerto Rico, since 1952
 * Commonwealth of the Northern Mariana Islands, since 1978

In 2016, the Washington, D.C. city council also selected "Douglass Commonwealth" as the potential name of State of Washington, D.C., following the 2016 statehood referendum, at least partially in order to retain the initials "D.C." as the state's abbreviation.

Commonwealth of Nations
The Commonwealth of Nations—formerly the British Commonwealth—is a voluntary association of 56 independent sovereign states, most of which were once part of the British Empire. The Commonwealth's membership includes both republics and monarchies. The Head of the Commonwealth is King Charles III, who also reigns as monarch directly in the 15 member states known as Commonwealth realms since his accession in 2022.

Commonwealth of Independent States
The Commonwealth of Independent States (CIS) is a loose alliance or confederation consisting of nine of the 15 former Soviet Republics, the exceptions being Turkmenistan (a CIS associate member), Lithuania, Latvia, Estonia, Ukraine, and Georgia. Georgia left the CIS in August 2008 following the 2008 invasion of the Russian military into South Ossetia and Abkhazia. Its creation signalled the dissolution of the Soviet Union, its purpose being to "allow a civilised divorce" between the Soviet Republics. The CIS has developed as a forum by which the member-states can co-operate in economics, defence, and foreign policy.

United Kingdom
Labour MP Tony Benn sponsored a Commonwealth of Britain Bill several times between 1991 and 2001, intended to abolish the monarchy and establish a British republic. It never reached second reading.

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

title: Commonwealth


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Commodore 1541

The Commodore 1541 (also known as the CBM 1541 and VIC-1541) is a floppy disk drive which was made by Commodore International for the Commodore 64 (C64), Commodore's most popular home computer. The best-known floppy disk drive for the C64, the 1541 is a single-sided 170-kilobyte drive for 5¼" disks. The 1541 directly followed the Commodore 1540 (meant for the VIC-20).

The disk drive uses group coded recording (GCR) and contains a MOS Technology 6502 microprocessor, doubling as a disk controller and on-board disk operating system processor. The number of sectors per track varies from 17 to 21 (an early implementation of zone bit recording with 4 constant angular velocity zones). The drive's built-in disk operating system is CBM DOS 2.6.

Introduction
The 1541 was priced at under US$400 at its introduction. A C64 plus a 1541 cost about $900, while an Apple II with no disk drive cost $1,295. The first 1541 drives produced in 1982 have a label on the front reading VIC-1541 and have an off-white case to match the VIC-20. In 1983, the 1541 switched to having the familiar beige case and a front label reading simply "1541" along with rainbow stripes to match the Commodore 64.

By 1983 a 1541 sold for $300 or less. After a home computer price war instigated by Commodore, the C64 and 1541 together cost under $500. The drive became very popular and difficult to find. The company said that the shortage occurred because 90% of C64 owners bought the 1541 compared to its 30% expectation, but the press discussed what Creative Computing described as "an absolutely alarming return rate" because of defects. The magazine reported in March 1984 that it received three defective drives in two weeks, and Compute!'s Gazette reported in December 1983 that four of the magazine's seven drives had failed; "COMPUTE! Publications sorely needs additional 1541s for in-house use, yet we can't find any to buy. After numerous phone calls over several days, we were able to locate only two units in the entire continental United States", reportedly because of Commodore's attempt to resolve a manufacturing issue that caused the high failures.

The early (1982 to 1983) 1541s have a spring-eject mechanism (Alps drive), and the disks often fail to release. This style of drive has the popular nickname "Toaster Drive", because it requires the use of a knife or other hard thin object to pry out the stuck media just like a piece of toast stuck in an actual toaster. This was fixed later when Commodore changed the vendor of the drive mechanism (Mitsumi) and adopted the flip-lever Newtronics mechanism, greatly improving reliability. In addition, Commodore made the drive's controller board smaller and reduced its chip count compared to the early 1541s (which had a large PCB running the length of the case, with dozens of TTL chips). The beige-case Newtronics 1541 was produced from 1984 to 1986.

Versions and third-party clones
All but the very earliest non-II model 1541s can use either the Alps or Newtronics mechanism. Visually, the first models, of the VIC-1541 denomination, have an off-white color like the VIC-20 and VIC-1540. Then, to match the look of the C64, CBM changed the drive's color to brown-beige and the name to Commodore 1541.

The 1541's numerous shortcomings opened a market for a number of third-party clones of the disk drive. Examples include the Oceanic OC-118 a.k.a. Excelerator+, the MSD Super Disk single and dual drives, the Enhancer 2000, the Indus GT, Blue Chip Electronics's BCD/5.25, and CMD's FD-2000 and FD-4000. Nevertheless, the 1541 became the first disk drive to see widespread use in the home and Commodore sold millions of the units.

In 1986, Commodore released the 1541C, a revised version that offers quieter and slightly more reliable operation and a light beige case matching the color scheme of the Commodore 64C. It was replaced in 1988 by the 1541-II, which uses an external power supply to provide cooler operation and allows the drive to have a smaller desktop footprint (the power supply "brick" being placed elsewhere, typically on the floor). Later ROM revisions fixed assorted problems, including a software bug that causes the save-and-replace command to corrupt data.

Successors
The Commodore 1570 is an upgrade from the 1541 for use with the Commodore 128, available in Europe. It offers MFM capability for accessing CP/M disks, improved speed, and somewhat quieter operation, but was only manufactured until Commodore got its production lines going with the 1571, the double-sided drive. Finally, the small, external-power-supply-based, MFM-based Commodore 1581 3½-inch drive was made, giving 800 KB access to the C128 and C64.

Hardware
The 1541 does not have DIP switches to change the device number. If a user adds more than one drive to a system, the user has to cut a trace in the circuit board to permanently change the drive's device number, or hand-wire an external switch to allow it to be changed externally. It is also possible to change the drive number via a software command, which is temporary and would be erased as soon as the drive was powered off.

1541 drives at power up always default to device #8. If multiple drives in a chain are used, then the startup procedure is to power on the first drive in the chain, alter its device number via a software command to the highest number in the chain (if three drives were used, then the first drive in the chain would be set to device #10), then power on the next drive, alter its device number to the next lowest, and repeat the procedure until the final drive at the end of the chain was powered on and left as device #8.

Unlike the Apple II, where support for two drives is normal, it is relatively uncommon for Commodore software to support this setup, and the CBM DOS copy file command is not able to copy files between drives – a third party copy utility is necessary.

The pre-II 1541s also have an internal power source, which generates a lot of heat. The heat generation was a frequent source of humour. For example, Compute! stated in 1988 that "Commodore 64s used to be a favorite with amateur and professional chefs since they could compute and cook on top of their 1500-series disk drives at the same time". A series of humorous tips in MikroBitti in 1989 said "When programming late, coffee and kebab keep nicely warm on top of the 1541." The MikroBitti review of the 1541-II said that its external power source "should end the jokes about toasters".

The drive-head mechanism installed in the early production years is notoriously easy to misalign. The most common cause of the 1541's drive head knocking and subsequent misalignment is copy-protection schemes on commercial software. The main cause of the problem is that the disk drive itself does not feature any means of detecting when the read/write head reaches track zero. Accordingly, when a disk is not formatted or a disk error occurs, the unit tries to move the head 40 times in the direction of track zero (although the 1541 DOS only uses 35 tracks, the drive mechanism itself is a 40-track unit, so this ensured track zero would be reached no matter where the head was before). Once track zero is reached, every further attempt to move the head in that direction would cause it to be rammed against a solid stop: for example, if the head happened to be on track 18 (where the directory is located) before this procedure, the head would be actually moved 18 times, and then rammed against the stop 22 times. This ramming gives the characteristic "machine gun" noise and sooner or later throws the head out of alignment.

A defective head-alignment part likely caused many of the reliability issues in early 1541 drives; one dealer told Compute!'s Gazette in 1983 that the part had caused all but three of several hundred drive failures that he had repaired. The drives were so unreliable that Info magazine joked, "Sometimes it seems as if one of the original design specs ... must have said 'Mean time between failure: 10 accesses.'" Users can realign the drive themselves with a software program and a calibration disk. The user can remove the drive from its case and then loosen the screws holding the stepper motor that move the head, then with the calibration disk in the drive gently turn the stepper motor back and forth until the program shows a good alignment. The screws are then tightened and the drive is put back into its case.

A third-party fix for the 1541 appeared in which the solid head stop was replaced by a sprung stop, giving the head a much easier life. The later 1571 drive (which is 1541-compatible) incorporates track-zero detection by photo-interrupter and is thus immune to the problem. Also, a software solution, which resides in the drive controller's ROM, prevents the rereads from occurring, though this can cause problems when genuine errors do occur.

Due to the alignment issues on the Alps drive mechanisms, Commodore switched suppliers to Newtronics in 1984. The Newtronics mechanism drives have a lever rather than a pull-down tab to close the drive door. Although the alignment issues were resolved after the switch, the Newtronics drives add a new reliability problem in that many of the read/write heads are improperly sealed, causing moisture to penetrate the head and short it out.

The 1541's PCB consists mainly of a 6502 CPU, two 6522 VIA chips, and 2k of work RAM. Up to 48k of RAM can be added; this is mainly useful for defeating copy protection schemes since an entire disk track could be loaded into drive RAM, while the standard 2k only accommodates a few sectors (theoretically eight, but some of the RAM was used by CBM DOS as work space). Some Commodore users use 1541s as an impromptu math coprocessor by uploading math-intensive code to the drive for background processing.

Interface
The 1541 uses a proprietary serialized derivative of the IEEE-488 parallel interface, found in previous disk drives for the PET/CBM range of personal and business computers, but when the VIC-20 was in development, a cheaper alternative to the expensive IEEE-488 cables was sought. To ensure a ready supply of inexpensive cabling for its home computer peripherals, Commodore chose standard DIN connectors for the serial interface. Disk drives and other peripherals such as printers connect to the computer via a daisy chain setup, necessitating only a single connector on the computer itself.

Throughput and software
IEEE Spectrum in 1985 stated that:

"The one major flaw of the C-64 is not in the machine itself, but in its disk drive. With a reasonably fast disk drive and an adequate disk-operating system (DOS), the C-64 could compete in the business market with the Apple and perhaps with other business computers. With the present disk drive, though, it is hard-pressed to lose its image as a toy."

The C-64's designers blamed the 1541's slow speed on the marketing department's insistence that the computer be compatible with the 1540, which is slow because of a flaw in the 6522 VIA interface controller. Initially, Commodore intended to use a hardware shift register (one component of the 6522) to maintain fast drive speeds with the new serial interface. However, a hardware bug with this chip prevents the initial design from working as anticipated, and the ROM code was hastily rewritten to handle the entire operation in software. According to Jim Butterfield, this causes a speed reduction by a factor of five; had 1540 compatibility not been a requirement, the disk interface would have been much faster. In any case, the C64 normally cannot work with a 1540 unless the VIC-II display output is disabled via a register write to the DEN bit (register $D011, bit 4), which stops the halting of the CPU during certain video lines to ensure correct serial timing.

As implemented on the VIC-20 and C64, Commodore DOS transfers 300 bytes per second, compared to the Atari 810's 2,400 bytes per second, the Apple Disk II's 15,000 bytes per second, and the 300-baud data rate of the Commodore Datasette storage system. About 20 minutes are needed to copy one disk—10 minutes of reading time, and 10 minutes of writing time. However, since both the computer and the drive can easily be reprogrammed, third parties quickly wrote more efficient firmware that would speed up drive operations drastically. Without hardware modifications, some "fast loader" utilities (which bypassed routines in the 1541's onboard ROM) managed to achieve speeds of up to 4 kbit/s. The most common of these products are the Epyx Fast Load, the Final Cartridge, and the Action Replay plug-in ROM cartridges, which all have machine code monitor and disk editor software on board as well. The popular Commodore computer magazines of the era also entered the arena with type-in fast-load utilities, with Compute!'s Gazette publishing TurboDisk in 1985 and RUN publishing Sizzle in 1987.

Even though each 1541 has its own on-board disk controller and disk operating system, it is not possible for a user to command two 1541 drives to copy a disk (one drive reading and the other writing) as with older dual drives like the 4040 that was often found with the PET computer, and which the 1541 is backward-compatible with (it can read 4040 disks but not write to them as a minor difference in the number of header bytes makes the 4040 and 1541 only read-compatible). Originally, to copy from drive to drive, software running on the C64 was needed and it would first read from one drive into computer memory, then write out to the other. Only when Fast Hack'em and, later, other disk backup programs were released, was true drive-to-drive copying possible for a pair of 1541s. The user could, if they wished, unplug the C64 from the drives (i.e., from the first drive in the daisy chain) and do something else with the computer as the drives proceeded to copy the entire disk.

Media
The 1541 drive uses standard 5¼-inch double-density floppy media; high-density media will not work due to its different magnetic coating requiring a higher magnetic coercivity. As the GCR encoding scheme does not use the index hole, the drive was also compatible with hard-sectored disks. The standard CBM DOS format is 170 KB with 35 tracks and 256-byte sectors. It is similar to the format used on the PET 2031, 2040 & 4040 drives, but a minor difference in the number of header bytes makes these drives and the 1541 only read-compatible; disks formatted with one drive cannot be written to by the other. The drives will allow writes to occur, but the inconsistent header size will damage the data in the data portions of each track.

The 4040 drives use Shugart SA-400s, which were 35-track units, thus the format there is due to physical limitations of the drive mechanism. The 1541 uses 40 track mechanisms, but Commodore intentionally limited the CBM DOS format to 35 tracks because of reliability issues with the early units. It is possible via low-level programming to move the drive head to tracks 36–40 and write on them, this is sometimes done by commercial software for copy protection purposes and/or to get additional data on the disk.

However, one track is reserved by DOS for directory and file allocation information (the BAM, block availability map). And since for normal files, two bytes of each physical sector are used by DOS as a pointer to the next physical track and sector of the file, only 254 out of the 256 bytes of a block are used for file contents.

If the disk side is not otherwise prepared with a custom format, (e.g. for data disks), 664 blocks would be free after formatting, giving 664254 = $168,656 bytes$ (or almost $165 KB$) for user data.

By using custom formatting and load/save routines (sometimes included in third-party DOSes, see below), all of the mechanically possible 40 tracks can be used.

Owing to the drive's non-use of the index hole, it is also possible to make "flippy floppies" by inserting the diskette upside-down and formatting the other side, and it is commonplace and normal for commercial software to be distributed on such disks.

Tracks 36–42 are non-standard. The bitrate is the raw one between the read/write head and signal circuitry so actual useful data rate is a factor 5/4 less due to GCR encoding.

The 1541 disk typically has 35 tracks. Track 18 is reserved; the remaining tracks are available for data storage. The header is on 18/0 (track 18, sector 0) along with the BAM, and the directory starts on 18/1 (track 18, sector 1). The file interleave is 10 blocks, while the directory interleave is 3 blocks.

Header contents: The header is similar to other Commodore disk headers, the structural differences being the BAM offset ($04) and size, and the label+ID+type offset ($90).

$00–01 T/S reference to first directory sector (18/1) 02 DOS version ('A') 04-8F BAM entries (4 bytes per track: Free Sector Count + 24 bits for sectors) 90-9F Disk Label, $A0 padded A2-A3 Disk ID A5-A6 DOS type ('2A')

Uses
Early copy protection schemes deliberately introduce read errors on the disk, the software refusing to load unless the correct error message is returned. The general idea is that simple disk-copy programs are incapable of copying the errors. When one of these errors is encountered, the disk drive (as do many floppy disk drives) will attempt one or more reread attempts after first resetting the head to track zero. Few of these schemes have much deterrent effect, as various software companies soon released "nibbler" utilities that enable protected disks to be copied and, in some cases, the protection removed.

Commodore copy protection sometimes fails on specific hardware configurations. Gunship, for example, does not load if a second disk drive or printer is connected to the computer. Similarly Roland's Ratrace will crash if additional hardware is detected. The tape version will even crash if a floppy drive is switched on while the game is running.

title: Commodore 1541


text:
Commodore 1581

The Commodore 1581 is a 3½-inch double-sided double-density floppy disk drive that was released by Commodore Business Machines (CBM) in 1987, primarily for its C64 and C128 home/personal computers. The drive stores 800 kilobytes using an MFM encoding but formats different from the MS-DOS (720 kB), Amiga (880 kB), and Mac Plus (800 kB) formats. With special software it's possible to read C1581 disks on an x86 PC system, and likewise, read MS-DOS and other formats of disks in the C1581 (using Big Blue Reader), provided that the PC or other floppy handles the "720 kB" size format. This capability was most frequently used to read MS-DOS disks. The drive was released in the summer of 1987 and quickly became popular with bulletin board system (BBS) operators and other users.

Like the 1541 and 1571, the 1581 has an onboard MOS Technology 6502 CPU with its own ROM and RAM, and uses a serial version of the IEEE-488 interface. Inexplicably, the drive's ROM contains commands for parallel use, although no parallel interface was available. Unlike the 1571, which is nearly 100% backward-compatible with the 1541, the 1581 is only compatible with previous Commodore drives at the DOS level and cannot utilize software that performs low-level disk access (as the vast majority of Commodore 64 games do).

The version of Commodore DOS built into the 1581 added support for partitions, which could also function as fixed-allocation subdirectories. PC-style subdirectories were rejected as being too difficult to work with in terms of block availability maps, which were still very much in vogue, and which for some time had been the traditional way of inquiring into block availability. The 1581 supports the C128's burst mode for fast disk access, but not when connected to an older Commodore machine like the Commodore 64. The 1581 provides a total of 3160 blocks free when formatted (a block being equal to 256 bytes). The number of permitted directory entries was also increased, to 296 entries. With a storage capacity of 800 kB, the 1581 is the highest-capacity serial-bus drive that was ever made by Commodore (the 1-MB SFD-1001 uses the parallel IEEE-488), and the only 3½" one. However, starting in 1991, Creative Micro Designs (CMD) made the FD-2000 high density (1.6 MB) and FD-4000 extra-high density (3.2 MB) 3½" drives, both of which offered not only a 1581-emulation mode but also 1541- and 1571-compatibility modes.

Like the 1541 and 1571, a nearly identical job queue is available to the user in zero page (except for job 0), providing for exceptional degrees of compatibility.

Unlike the cases of the 1541 and 1571, the low-level disk format used by the 1581 is similar enough to the MS-DOS format as the 1581 is built around a WD1770 FM/MFM floppy controller chip. The 1581 disk format consists of 80 tracks and ten 512 byte sectors per track, per side, used as 40 logical sectors of 256 bytes each. Special software is required to read 1581 disks on a PC due to the different file system. An internal floppy drive and controller are required as well; USB floppy drives operate strictly at the file system level and do not allow low-level disk access. The WD1770 controller chip, however, was the seat of some early problems with 1581 drives when the first production runs were recalled due to a high failure rate; the problem was quickly corrected. Later versions of the 1581 drive have a smaller, more streamlined-looking external power supply provided with them.

1581 Image Layout
The 1581 disk has 80 logical tracks, each with 40 logical sectors (the actual physical layout of the diskette is abstracted and managed by a hardware translation layer). The directory starts on 40/3 (track 40, sector 3). The disk header is on 40/0, and the BAM (block availability map) resides on 40/1 and 40/2.

Header Contents

$00–01 T/S reference to first directory sector (40/3) 02 DOS version ('D') 04-13 Disk Label, $A0 padded 16-17 Disk ID 19-1A DOS type ('3D')

BAM Contents, 40/1

$00–01 T/S to next BAM sector (40/2) 02 DOS version ('D') 04-05 Disk ID    06 I/O byte 07 Autoboot flag 10-FF BAM entries for Tracks 1-40

BAM Contents, 40/2

$00–01 00/FF 02 DOS version ('D') 04-05 Disk ID    06 I/O byte 07 Autoboot flag 10-FF BAM entries for Tracks 41-80

title: Commodore 1581