![XF551 disk drive front](https://upload.wikimedia.org/wikipedia/commons/8/85/XF551_disk_drive_front.jpg)
The XF551 was the last
floppy disk drive
A floppy disk or floppy diskette (casually referred to as a floppy, or a diskette) is an obsolescent type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined w ...
produced by
Atari for the
8-bit series home computers. It was the first drive from the company that officially supported double-density, adding double-sided support, providing 360 kB of storage per disk. It also introduced a faster transfer speed when used in double-density mode, doubling performance. It was packaged in the new gray-colored
design language
A design language or design vocabulary is an overarching scheme or style that guides the design of a complement of products or architectural settings, creating a coherent design system for styling.
Objectives
Designers wishing to give their su ...
of the XE series computers.
Although an XE-styled drive was shown several times during 1985 and 1986, production waited while leftover inventories of the
Atari 1050
The Atari 1050 was a floppy disk drive for the Atari 8-bit family home computers, released in June 1983. It was compatible with the 90 kB single-density mode of the original Atari 810 it replaced, and added a new "enhanced" or "dual density ...
were sold off. By the time these ran out late in 1986, interest in the 8-bit line had waned and a new model was not put into production. At the same time, the success of the
Nintendo Entertainment System (NES) prompted Atari to repackage their 65XE as the
Atari XEGS
The Atari XE Video Game System (Atari XEGS) is an industrial redesign of the Atari 65XE home computer and the final model in the Atari 8-bit family. It was released by Atari Corporation in 1987 and marketed as a home video game console alongsid ...
games console, boasting it could be expanded to a complete computer with the addition of a keyboard and disk drive. Nintendo sued, noting that Atari had no disk drives to sell, forcing Atari to rush the drive to market in June 1987 even though the software was not ready.
The XF551 is generally considered the best of Atari's drive offerings; not only did it store three times as much data as the 1050, it was also twice as fast and almost silent in operation. Its release was marred by packaging it with an old version of
Atari DOS
Atari DOS is the disk operating system used with the Atari 8-bit family of computers. Operating system extensions loaded into memory were required in order for an Atari computer to manage files stored on a disk drive. These extensions to ...
, which did not support any of these new features. When this was finally addressed with the release of DOS XE a year later, the product went on to have a short but successful time in the market. Support was dropped, along with the entire 8-bit line, in 1992.
History
815
When the
Atari 8-bit family began shipping in 1979, Atari showed two
floppy disk drive
A floppy disk or floppy diskette (casually referred to as a floppy, or a diskette) is an obsolescent type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined w ...
systems, the
810
__NOTOC__
Year 810 ( DCCCX) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar.
Events
By place Byzantine Empire
* Spring – The Venetian dukes change sides again, submitting to Ki ...
and the 815. The 810 used the then-standard single-density
FM encoding format that stored about 90 kB of data, while the 815 packaged two drives in a single case, both supporting a double-density
MFM encoding format of 180 kB. Small numbers of the 815 began shipping in June 1980, but mass production never started. Nevertheless, this brief introduction set the standard for double-density drives that other companies would later support.
Turmoil at Atari
![Atari-130XE](https://upload.wikimedia.org/wikipedia/commons/9/9a/Atari-130XE.jpg)
In 1983,
Commodore International
Commodore International (other names include Commodore International Limited) was an American home computer and electronics manufacturer founded by Jack Tramiel. Commodore International (CI), along with its subsidiary Commodore Business Mac ...
sparked off a
price war
A price is the (usually not negative) quantity of payment or compensation given by one party to another in return for goods or services. In some situations, the price of production has a different name. If the product is a "good" in the ...
in the
home computer market by repeatedly lowering the price of its
VIC-20
The VIC-20 (known as the VC-20 in Germany and the VIC-1001 in Japan) is an 8-bit home computer that was sold by Commodore Business Machines. The VIC-20 was announced in 1980, roughly three years after Commodore's first personal computer, the ...
and
Commodore 64 (C64) lines in order to undercut the
TI-99/4A
The TI-99/4 and TI-99/4A are home computers released by Texas Instruments in 1979 and 1981, respectively. Based on the Texas Instruments TMS9900 microprocessor originally used in minicomputers, the TI-99/4 was the first 16-bit home computer. ...
.
Atari had recently introduced the
Atari 1200XL at a higher price point, and its lineup could not be produced profitably at the rapidly falling market prices. Atari eventually introduced lower-cost models, the 600XL and 800XL, but these were repeatedly delayed and did not reach market until late in 1983, too late to have an impact. Combined with the effects of the
video game crash of 1983
The video game crash of 1983 (known as the Atari shock in Japan) was a large-scale recession in the video game industry that occurred from 1983 to 1985, primarily in the United States. The crash was attributed to several factors, including ma ...
, the company was soon losing over a million dollars a day.
The success of the C64 did not save Commodore from problems of its own. In January 1984, Commodore president
Jack Tramiel
Jack Tramiel ( ; born Idek Trzmiel; December 13, 1928 – April 8, 2012) was an American businessman and Holocaust survivor, best known for founding Commodore International. The Commodore PET, VIC-20 and Commodore 64 are some home comput ...
got into some sort of argument with
chairman of the board,
Irving Gould
Irving Gould (1919–2004) was a Canadian businessman credited with both saving and sinking Commodore.
Commodore was originally formed in Canada and initially produced mechanical typewriters and calculators. In 1965, Jack Tramiel, Commodore's foun ...
, and left the company. After spending some time looking for ways to re-enter the field, in July he arranged a deal to buy Atari from its owners,
Warner Communications, for no cash and several million in
promissory notes.
Attempting to bring the company back to some semblance of profitability, the new management laid off whole divisions while working to bring their new
Atari ST, to market as soon as possible. During this period many advanced projects within the company were cancelled. This included Atari's own 32-bit efforts and several advanced
game consoles. Warehouses filled with stocks of the 8-bit line were sold off at fire-sale prices pending the introduction of cost-reduced models, the XE series.
XF521
Atari had already been working on several upgrades to the 1050 series, including the 1050CR, for cost-reduced. This replaced the original custom
MOS 6507-based interface card with one using the
Intel 8048
The MCS-48 microcontroller series, Intel's first microcontroller, was originally released in 1976. Its first members were 8048, 8035 and 8748. The 8048 is probably the most prominent member of the family. Initially, this family was produced u ...
microcontroller. The 8048 included internal RAM and ROM and thus greatly simplified the overall design of the interface. The Tramiels took the CR and repackaged it to match the silver-grey styling of the XE and ST line. While introducing the XE's at the January 1985
Consumer Electronics Show, the company previewed the design as the XF521. It was rumored it would also support true double-density mode.
When the Tramiels took over the company they found huge stocks of unsold 1050s, and repeatedly delayed the XF521 while selling these off. By the time the stocks of these drives finally dwindled in 1986, the ST was selling strongly and the company had lost interest in the 8-bit line. Any mention of the XF521 disappeared.
Nintendo sues
![Atari XEGS](https://upload.wikimedia.org/wikipedia/commons/c/c0/Atari_XEGS.jpg)
In October 1985,
Nintendo introduced the
Nintendo Entertainment System to North America. By late 1986 it was a runaway success, prompting the Tramiels to reexamine the
games console market. At the time, Atari had warehouses of the
Atari 5200
The Atari 5200 SuperSystem or simply Atari 5200 is a home video game console introduced in 1982 by Atari, Inc. as a higher-end complement for the popular Atari Video Computer System. The VCS was renamed to the Atari 2600 at the time of the 520 ...
and
Atari 7800
The Atari 7800 ProSystem, or simply the Atari 7800, is a home video game console officially released by Atari Corporation in 1986 as the successor to both the Atari 2600 and Atari 5200. It can run almost all Atari 2600 cartridges, making it one ...
which were put back on the market, but neither had been in production for some time and were built on pre-XE systems with no capability to produce more. This led to the decision to introduce a new console, the
Atari XEGS
The Atari XE Video Game System (Atari XEGS) is an industrial redesign of the Atari 65XE home computer and the final model in the Atari 8-bit family. It was released by Atari Corporation in 1987 and marketed as a home video game console alongsid ...
, which was essentially a repackaged Atari 65XE and would run existing 8-bit games.
As part of the XEGS launch, Atari boasted about its large library of software as well as its ability to be used as a true computer with the supplied keyboard and optional peripherals including a floppy drive. By this point, stocks of the 1050 had already run out. This led to about six months where no official Atari drives were available for the line, and it appeared the company was in no hurry to introduce the XF521.
Nintendo sued Atari for
false advertising, noting that Atari claimed the system supported a floppy but did not actually have drives for sale.
Redesign
At some point during this period, Atari decided to completely redesign the drive. The computer market was already well into the conversion from 5.25 to 3.5-inch disks, and 5.25 double-density double-sided drives were now commonplace and inexpensive. Moreover, after the introduction of the
IBM PC, drives using the standard 34-bit
ribbon cable
A ribbon cable (also known as multi-wire planar cable) is a cable with many conducting wires running parallel to each other on the same flat plane. As a result, the cable is wide and flat. Its name comes from its resemblance to a piece of ribb ...
had proliferated. This allowed drives to be easily swapped.
Earlier Atari drives used a customized controller that communicated with the host computer's
Atari SIO
The Serial Input/Output system, universally known as SIO, was a proprietary peripheral bus and related software protocol stacks used on the Atari 8-bit family to provide most input/output duties for those computers. Unlike most I/O systems of the ...
bus using a 6507 running at 500 kHz. For historical reasons, these drives used a 19.2 kbps speed to transfer data, although this was not a limitation of the bus itself. Third party drives normally used higher speeds, when run with suitable third-party DOSes, with some operating as high as the 52 kbps "Warp Speed" of the
Happy 810. For the new drive, Atari decided to double the rate to 38 kbps, although only when used with double-density disks.
Atari DOS
Atari DOS is the disk operating system used with the Atari 8-bit family of computers. Operating system extensions loaded into memory were required in order for an Atari computer to manage files stored on a disk drive. These extensions to ...
2.5, introduced for the 1050 in 1983, did not support either capability. This had led to a thriving market for 3rd party DOSes which had long supported double-density modes and the higher transfer speeds. Among these was
DOS XL
DOS XL is a discontinued Disk Operating System (DOS) written by Paul Laughton, Mark Rose, Bill Wilkinson, and Mike Peters and published by Optimized Systems Software (OSS) for the Atari 8-bit family of home computers. It was designed to be com ...
, introduced in 1983 by
Optimized Systems Software
Optimized Systems Software (OSS) was a company that produced disk operating systems, programming languages with integrated development environments, and applications primarily for the Atari 8-bit family of home computers. OSS was best known f ...
(OSS), authors of the original Atari DOS. Atari contracted OSS to produce a new version, initially known as ADOS, which added double-sided support to its existing double-density and high-speed features.
Introduction
Prior to the Nintendo lawsuit, Atari claimed the only holdup on the new drive was that the documentation for the new DOS was not ready. When the lawsuit was launched, Atari put the drive on the market immediately in June 1987, shipping it with the existing Atari DOS 2.5. This was a success, as it did result in the lawsuit being dropped.
However, DOS 2.5 lacked support for the new modes, which essentially made it a direct replacement for the 1050 rather than the major upgrade it was intended to be. DOS XE did not ship until 1988/89, by which time the same modes were already supported by a variety of 3rd party solutions like
SpartaDOS
Atari DOS is the disk operating system used with the Atari 8-bit family of computers. Operating system extensions loaded into memory were required in order for an Atari computer to manage files stored on a disk drive. These extensions to ...
. Nevertheless, shipping DOS 2.5 with the drives for over a year led to significant confusion in the market.
The drive was otherwise very well received. It was "eerily silent during operation", so much so that reviews noted it was impossible to tell if it was being used without looking at the access LED. The only real complaints were the rear position of the power button, which made it difficult to access in some computer desks, and that it was very "fussy" about the diskettes, rejecting as many as 20% of low-cost floppies. In the end, it was "heartily recommend"ed, and "the best thing that's happened to Atari's 8-bit computer line since the birth of the 130XE".
By the late 1980s, sales of the XE series were primarily to low-cost markets like eastern Europe and South America. These markets were so cost-sensitive that even the low price of the XF551 was too much for most users, and the most common storage mechanism was the
XC12 cassette tape system. The entire 8-bit series was eventually discontinued in 1992.
Description
![XF551 disk drive rear](https://upload.wikimedia.org/wikipedia/commons/f/ff/XF551_disk_drive_rear.jpg)
The XF551 was slightly smaller than the 1050 it replaced, but overall similar. It connected to the computer or XEGS using the SIO port, with two ports on the back, in and out, to allow it to be daisy chained to other peripherals. The back also had the jack for the
power supply
A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As a ...
, the power switch, and a
DIP switch
A DIP switch is a manual electric switch that is packaged with others in a group in a standard dual in-line package (DIP). The term may refer to each individual switch, or to the unit as a whole. This type of switch is designed to be used on a ...
that allowed the drive to be numbered 1 through 4.
When operating in legacy modes to read or write to disks from the 810 or 1050, the system transferred data at the original standard speed of 19,040 bps. This speed was much lower than the SIO was capable of, and had been selected simply because that was the limit of the
logic analyzer
A logic analyzer is an electronic instrument that captures and displays multiple signals from a digital system or digital circuit. A logic analyzer may convert the captured data into timing diagrams, protocol decodes, state machine traces, a ...
available to the engineers designing the original 810s. The XF551, when operating in double-density mode, doubled this to 38,908 bps.
SIO is a
serial bus
In telecommunication and data transmission, serial communication is the process of sending data one bit at a time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication, where several bits are ...
that sends commands and data over the same in and out pins. This requires the devices on the SIO to be "smart", listening for commands being sent to their device number, decoding the instructions, and responding in kind. In previous Atari drives, this had been accomplished with the 6507, a cut-down version of the
MOS 6502
The MOS Technology 6502 (typically pronounced "sixty-five-oh-two" or "six-five-oh-two") William Mensch and the moderator both pronounce the 6502 microprocessor as ''"sixty-five-oh-two"''. is an 8-bit microprocessor that was designed by a small te ...
that was being used in the
Atari VCS
The Atari 2600, initially branded as the Atari Video Computer System (Atari VCS) from its release until November 1982, is a home video game console developed and produced by Atari, Inc. Released in September 1977, it popularized microprocessor- ...
console. The console ran at 1.1 MHz, but some 6507s supplied by
Synertek failed to run at this speed reliably and were passed off to be used as SIO controllers running at lower speeds.
For the new drive, which operated at higher speeds and had more features, the 6507 was replaced by the
Intel 8040,
microcontrollers that included ROM and RAM on the same chip and thus allowed a great simplification of the controller. The 8040 versions did not have enough ROM for the entire driver, so later models moved to the 8050 with 4 kB for a further simplification. These chips, originally introduced in 1976, were now available for pennies and ran at a relatively fast 8.33 MHz. The controller was paired with the then-standard
Western Digital FD1772 floppy disk controller, a late-model version of WD's drive controllers that implemented almost all of the required circuitry in a single 28-pin chip and thereby lowered the total cost of implementation.
Previous to the XF551, users would generally use both sides of a floppy disk by formatting one side, flipping the disk over, and formatting the second, the so-called "
flippy disk". This presented a potential problem with the new drive; if a user flipped the disk and formatted using the default double-sided format, any data on the other side would be erased. To prevent this, the system only allowed formatting if the disk's timing hole was in the correct "up" position, otherwise it would only format in the older single-sided formats. For those that needed to make flippys for use with other drives, the XF551 Enhancer appeared, a modification that allowed the drive to ignore the timing hole and write to either side of the disk.
Most of the drives sold used a
Mitsumi Electric
was a Japanese manufacturer of consumer electronic components, founded in 1954.
The company was listed on the Tokyo Stock Exchange, was constituent of the Nikkei 225 stock index and provided its products through its subsidiaries in Asia, Euro ...
mechanism, although a small number of later models replaced this with one from
Chinon Industries. They can be distinguished as the Mitsumi version has a rectangular LED on the front while the Chinon version is round. The Chinon versions also used the timing hole for both formatting and reading, and thus could not work with flippy disks at all. This limitation could be removed with the Enhancer. Because the drive mechanism was connected to the board using a standard connector, it was possible to replace it with a 3.5-inch mechanism, and this became quite popular.
In contrast to the 810 and 1050, which ran at the non-standard speed of 288 RPM, the XF551 ran at the industry standard 300 RPM. This caused problems for a small number of programs whose
copy protection
Copy protection, also known as content protection, copy prevention and copy restriction, describes measures to enforce copyright by preventing the reproduction of software, films, music, and other media.
Copy protection is most commonly found o ...
relied on accurately timing the drive.
One design feature of DOS XE was that it always wrote files to side one of the floppy until it ran out of room. This meant the disks could be inserted in older drives also being run with DOS XE, or compatible double-density 3rd party DOSes, and at least read the files on that side.
Notes
References
Citations
Bibliography
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*
*
* {{cite interview
, first=Kevin , last=Savetz
, title=ANTIC Interview 177 - Steve Smith, ANTIC chip
, date=9 February 2016
, url=https://ataripodcast.libsyn.com/antic-interview-177-steve-smith-antic-chip
Further reading
Atari DOS 2.5 XF551 Disk Drive Owner's ManualAtari Dos Xe Owner's Manual
Atari hardware
Atari 8-bit family