• Atari 8-Bit Computers: Frequently Asked Questions (7/29)

    From Michael Current@21:1/5 to Marc G. Frank on Mon Apr 8 21:54:58 2019
    [continued from previous message]

    =================================
    Happy 1050 Enhancement, by Happy Computers, Inc. (Richard Adams), 1984
    - Board includes a 6502 microprocessor and a RAM buffer:
    Up to 36 sectors (SD mode: 2 tracks / 4608 bytes)
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - "Happy" Warp Speed standard high speed reads disks up to 500% times faster
    than standard 1050 with any software; supporting software also supports
    buffered fast write with verify
    - Navigate/edit/create nonstandard format disks
    - Warp Speed Software disk included, contains Warp Speed DOS
    (modified Atari DOS 2.0S), Diagnostic, Sector Copier, Happy Backup, Happy
    Compactor, Multi Drive Happy Backup, Tracer
    - (Rev 2 ROM) ICD US Doubler emulation for UltraSpeed software compatibility
    - IBMXFR IBM Transfer Program included, 1988- (Warp Speed Software v. 7.10)
    - Adds SS-DD "IBM format": 40 tracks, 9 sectors of 512 bytes = 180KiB
    - Software sold separately by Happy Computers:
    - Warp Speed DOS XL, including under cartridge, under ROM and Axlon RAM
    versions (modified DOS XL by Optimized Systems Software (OSS))
    - TOP DOS version 1.5, by Eclipse Software
    - Software sold separately:
    - Happy Version Archiver/Editor, by Spartan Software of Minnesota, 1984
    - Also marketed by B&C ComputerVisions as: Scan-It!/1050 Happy, 1987
    - Fuzzy/Phantom Sector Maker, by CSS, 1986 (Antic 9/86p48)
    - Archiver Enhancement, by Computer Software Services (CSS), 1987
    - Super Archiver/Editor 3.0 and The Archiver Tracer
    - Happy Doubler, by Innovative Concepts, 1989
    - US Doubler compatible/UltraSpeed capable (software solution)
    - Ability to configure drives as D5: through D8:
    - Hardware upgrades for Happy 1050 Enhancement:
    o Happy 1050 Controller, by Happy Computers, Inc., 1986
    - Hardware switch to select Happy Fast or Slow mode
    - Hardware switch to control write protection, with LED indicator
    - Write to reverse side of disks without punching holes
    o Imitator Controller, by Innovative Concepts, 1987
    - Hardware switch to select Happy Fast or Slow mode
    - 3-position switch for write protect mode:
    1) As normal, 2) Do not write, and 3) Will write to any disk
    - Two-color LED for write-protect status
    o IC Chip, by Innovative Concepts, 1988-11-11
    - US Doubler compatible/UltraSpeed capable (replacement Happy ROM)
    Happy 1050 Maximizer, by Happy Computers, Inc.
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - Happy 1050 Controller upgrade compatible
    - Maximizer to Enhancement Upgrade available from Happy Computers
    High Speed Board 1050, by Irata Verlag, 1985 (West Germany)
    - Happy 1050 Enhancement clone
    1050 Lazer Enhancement, from Utility House (1986) (UK)
    - Happy 1050 Enhancement clone
    - Shipped with The Lazer Drive Supercharger software from Utility House
    1050 IS Plate, by Innovated Software (Robert Perry), 1986
    - Add-on board includes 6502 and 16KiB RAM buffer. Plugs into 6507 socket.
    - Happy 1050 Enhancement compatible/near-clone
    - Emulation of: IS Doubler, US Doubler, standard 1050, Archiver/810
    (UltraSpeed and Archiver software compatible)
    - System supports up to 16 drives
    - Shipped with 2-sided disk including IS Doubler/US Doubler emulation, high
    speed disk copiers (standard and 130XE versions), file loader, custom disk
    formatter (including bad sectors), track tracer
    - Late units: Software instead built-in on ROM
    - Sold separately for use with early units: ISP Gremlin Grabber
    - Most units shipped with Gremlin Grammer II or Gremlin Grabber III
    Klone, by Computer Software Services (CSS), 1986 (USA)
    - Happy 1050 Enhancement clone
    - Happy Warp Speed Software (pre-7.0) included
    Klone II, by Computer Software Services (CSS), 1987 (USA)
    - Happy 1050 Enhancement clone
    - Happy Warp Speed Software (7.0) included
    Copy Card 7.0, by ????, year ???? (Europe)
    - Happy 1050 Enhancement compatible/near-clone
    Hyper Drive, by Chaos! Computers (UK), 1994
    - Happy 1050 Enhancement clone
    - Shipped with software package (Ver. II): Hyper Fast DOS, Hyper Sector
    Copier, Hyper Back-Up Sytem, US Doubler Emulation, HyperCompaction,
    Diagnostic Tester, Archiver/810 Emulation, Multi Drive Back-Up
    - See review & ad, Page 6's New Atari User #75 pp. 30-37, 39

    US Doubler, by ICD, 1984
    - ROM replacement chip and 128 byte RAM chip; some drives require moving two
    jumpers also
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - "UltraSpeed" standard high speed "54K baud" via sector skewing; supporting
    software required for high speed (initially: SpartaDOS)
    - Many units shipped with ICD SpartaDOS
    SuperMax, by Super Products
    - US Doubler compatible/UltraSpeed capable
    - Add-on board, switch between standard and replacement drive ROM
    IS Doubler, by Innovated Software (Robert Perry), 1985?
    - US Doubler clone

    Warp Drive, from Stocksoft (UK), 1986
    - Add-on control board replaces two chips
    - Back up including most types of bad sectors
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - Shipped with public domain backup software, double density Menu Maker
    - Archiver/810 compatible (Rev 2 and up)
    Super Archiver, by Computer Software Services (CSS), 1987
    - Add-on board, known as: "Super Archiver Mod", "1050 Super Archiver Chip"
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - Archiver/810 compatible; US Doubler compatible/UltraSpeed capable
    - Navigate/edit/create nonstandard format disks
    - Included software: Super Archiver/Editor 3.0, Super Archiver (skew) 3.1,
    Super Archiver Fuzzy Sector Maker, The Archiver Tracer, Super Archiver
    Diagnostic
    - Also sold without software (B&C ComputerVisions)
    - Bit-Writer upgrade sold separately by CSS (1988):
    - Writes bits rather than sectors, for increased copy capabilities
    Super Archiver II, by CSS, 1988
    - Enhanced density version of CSS Super Archiver
    - Sold complete or as a software-only upgrade for CSS Super Archiver
    - Software: Super Archiver/Editor 3.03 (enhanced density), Super Archiver
    Fuzzy Sector Maker (enhanced density), The Archiver Tracer, Super Archiver
    Diagnostic

    Reproducer, by Gardner Computing, 1984
    - Navigate/edit/create nonstandard format disks
    - Software included
    Density Doubler 1050, by Duplicating Technologies (DT), 1986
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - Whole track buffering (18 sectors / 8KiB) "up to three times faster"
    1050 Duplicator, by Duplicating Technologies (DT), 1986
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - Whole track buffering (18 sectors / 8KiB) "up to three times faster"
    - Navigate/edit/create nonstandard format disks (including enhanced density)
    - Includes copying software
    - Sources (Jim Patchell):
    http://www.oldcrows.net/~patchell/atari/duplicator.html
    - CheerUp Upgrade, by Happy Computers, Inc., 1987
    - Changes 1050 Duplicator to Happy 1050 Enhancement software compatible

    1050 Turbo, by Bernhard Engl for Gerald Engl Computertechnik, 1985-1988
    - Hardware includes replacement ROM (no microprocessor; no RAM buffer)
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - "Turbodrive" standard high speed 68200 bit/s ("70000 baud") via sector
    skewing; high speed supporting software NOT necessary for high speed,
    instead supporting software is loaded from drive ROM
    - Software on ROM: Backup Machine II, Magic Formatter, Maintenance Box
    - http://www.strotmann.de/~cas/Infothek/1050Turbo/
    Top Drive 1050, by Ataserw (1987 or 1988)
    - 1050 Turbo clone (ROM by P.Z. Karen, brand of of LDW)
    - Software: TURBO DOS ("TUR-DOS") disk or cartridge. Known versions:
    - TURBO DOS (c) 1989 ver 2.5 (disk?)
    - TUR DOS - (c) 1990 rev 4.0 (cartridge)
    wszelkie prawa JS & ATASERW Tychy
    - Available upgrade project converts to Happy 1050 Enhancement compatible
    - Details here: http://preview.tinyurl.com/npla4t6

    Speedy 1050 (Mini-Speedy), by Compy-Shop, 1986
    - Includes 65C02 microprocessor, 8KiB RAM buffer, 8KiB program ROM space
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - "Speedy" standard high speed; supporting software required for high speed
    - Speedy 1050N: Internal add-on
    - Speedy 1050NE: External add-on
    - Speedy 1050T: Internal add-on with (external) track display
    - Speedy 1050TE: External add-on with track display
    - Above models: Optional hardware switches for write-protect and
    fast/slow mode control
    - Mini-Speedy S: Internal add-on with 8KiB Sector Copy program in ROM
    - Mini-Speedy D: Internal add-on with 8KiB mini-Bibo-DOS in ROM
    - Mini-Speedy DS: Internal add-on with both Sector Copy and mini-Bibo-DOS
    programs in ROM, hardware switch selectable
    - Super-Speedy prototype: equivalent to Mini-Speedy DS plus track display
    and 192KiB RAM buffer, requiring special software support
    - System disk includes: Speedy Test, Sector Copier. Mini-Speedy system disk
    also includes: Speedy Backup, Speed Init, DiskMapper, HSS Copier
    - Sold separately by Martin Reitershan Computertechnik:
    - Turbo-Speedy DC -- Upgrade replaces mini-Bibo-Dos with the company's
    Turbo-DOS XL/XE, also new firmware; 24KiB ROM space total
    Mega Speedy (Guus Assmann & Matthias Reichl, 2014)
    - Out-of-the-box it supports the original 1050, Speedy, Super Speedy,
    a new Mega Speedy, 1050 Turbo and 1050 Duplicator modes.
    - Hardware can also emulate Happy, US Doubler, Super Archiver, and Supermax,
    but you need to provide the ROMs for these upgrades yourself.
    - More info: http://www.realdos.net/MegaSpeedy.html
    - Software and firmware: http://www.horus.com/~hias/megaspeedy/
    - Documentation: http://www.realdos.net/MegaDocs.html

    Tygrys 1050, by Marek Bojarski of Navitron (1988)
    - Version 1.0: US Doubler clone?
    - Version 2.0: US Doubler and 1050 Turbo compatibility?

    TOMS Multi Drive 1050 (1990)
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - Adds SS-DD "IBM format": 40 tracks, 9 sectors of 512 bytes = 180KiB
    - Compatibilities: Happy 1050 Enhancement, 1050 Turbo, 1050 Duplicator
    - Software: TOMS Copier, Track Master, Tracer, Get Track, Weak Writer,
    Bad Formatter, Track Writer, IBM DOS, IBM 360, Turbo Drive Kopier

    Other:
    -----
    Protector, by Computer Software Serices (CSS), for 810/1050/Indus GT, 1983
    - Includes hardware and software
    - Bad sector generator; also move/rearrange data, scramble directories Silencer, by CSS, for 810/1050, 1984
    - Eliminates loud drive sounds when reading bad sectors
    - Write to both sides of any disk without notching disks
    Over-Write [1050 version], by Computer Support, 1985
    - Write to side 2 of any disk without notching out a hole in the disk
    Bad Sector, by Computer Support, 1985
    - Write bad sectors to any diskette; can backup some protected disks Write-Right, by Duplicating Technologies, 1986
    - Write to both sides of any disk without notching disks
    Electronic Phantom Sector Maker, by CSS, 1987 (Antic 9/87p28)
    - Installs into any drive, no other modification needed
    - Can be combined with other upgrades including Happy 1050 Enhancement,
    Archiver, and Duplicator
    - Make fuzzy/phantom sectors or fuzz portions of sectors
    - Find/Display valid data, CRC errors and phantom sectors
    - Deluxe version: Allows you to switch between CRC and phantom sectors
    without having to readjust hardware module each time
    IC1050 Controller, by Innovative Concepts, 1989
    - 3-position switch for write protect mode:
    1) As normal, 2) Do not write, and 3) Will write to any disk
    - Two-color LED for write-protect status

    ------------------------------

    Subject: 3.2.3) What is the Atari XF551 Disk Drive?

    The Atari XF551 disk drive was introduced in June 1987 as a replacement for
    the 1050 disk drive. The XF551 is fully backward compatible with the 1050, with the addition of two new modes of operation: a true "double density" mode offering 180KiB of data storage per (single-sided) diskette (fully compatible with 3rd party double density drives for the Atari), and a "double-sided
    double density" mode offering 360KiB of data storage per (2-sided) diskette.

    Unlike the 810 or 1050, the XF551 drive has two drive heads, so it can read/write to both sides of a 2-sided floppy disk (in double-sided double density 360KiB disk mode). The 360KiB mode of the XF551 writes "backwards" to the second side of the disk in comparison to the way data would be stored on the reverse side of a disk, inserted into the drive upside-down, in single- sided double density 180KiB mode.

    When working with double-sided double density 360KiB disks, the XF551 is also capable of communicating with the computer at about twice data rate of the earlier Atari 1050 or 810 drives. This XF551 high speed mode is supported by: DOS XE, SpartaDOS X, XDOS, MyPicoDos, Micro-SpartaDOS, SuperDOS, Turbo-DOS, BW-DOS. A patch was also developed for SpartaDOS 3.2d.

    The front of the XF551 features a "Disk busy" indicator light. (Notably,
    there is no power indicator light on the XF551.) The rear of the unit
    includes a power on/off switch, a Power jack, two SIO ("Peripheral") ports,
    and Drive Select DIP switches:
    Left & Right down: Drive 1
    Left down, Right up: Drive 2
    Left up, Right down: Drive 3
    Left & Right up: Drive 4

    More features/specifications of the XF551 disk drive:
    - 8040/8050 MPU. One of:
    - Intel 8050 microcontroller (MCU) @ 8.3333MHz, C070235
    - Intel 8040 microcontroller (MCU) @ 8.3333MHz, CB101393
    - The 8050 has internal ROM space that is not used in the XF551.
    - (Initial Atari and media reports incorrectly indicated a 6507 MPU.)
    - (The DOS XE: XF551 manual incorrectly indicates 18.3333MHz.)
    - Western Digital WD1772 Floppy Disk Controller (FDC) C026028
    - Late production units substituted: Western Digital WD1770
    - SIO Data rate (normal): 19,040 bit/s (NTSC), 18,688 bit/s (PAL)
    (high speed): 38,908 bit/s (NTSC), 38,553 bit/s (PAL)
    - High speed available in DS/DD 360KiB mode operation only
    - Rotation rate: 300 RPM
    Virtually all other Atari-specific drives spin at 288 RPM. This results in
    rare compatibility issues. Specifically, these commercial disks do not load
    in, and can possibly be damaged (!) by the XF551:
    - Flight Simulator II (subLOGIC)
    - Blue Max (Synapse) (I have personally destroyed multiple Blue Max
    disks with the XF551 drive! -mc)
    - Bank Street Writer (Broderbund). Conflicting reports about this one.
    - Boulder Dash II (Databyte release?)
    - Inside (Spektra, 1990?--original Polish version?)
    - Media used is the same as for the Atari 810.

    Operating modes Single Dual Double Double
    Encoding Method FM MFM MFM MFM
    Number of sides 1 1 1 2
    Total tracks 40 40 40 80
    Sectors per track 18 26 18 18
    Bytes per sector 128 128 256 256 (total capacity)
    Total Bytes 92,160 133,120 184,320 368,640 (total capacity)

    The XF551 drive features a horizontal slot with latch bar door mechanism.
    To complete the insertion of a disk, turn the latch bar clockwise ninety degrees. To release the disk, turn the latch counterclockwise.

    XF551 drives were manufactured for Atari in two versions, both made in Japan.
    - Mitsumi XF551 (most units)
    - Earlier production; common in North America and Europe.
    - Disk Busy light is rectangular, green, and is located below the
    "straight" drive latch
    - See: http://farm5.static.flickr.com/4052/4669794021_de721aa12d_b.jpg
    - When the drive latch is opened, an inserted disk stays in place until
    removed manually.
    - Inserting a disk does not cause any drive activity.
    - Like the Atari 810 and 1050, the Mitsumi XF551 ignores the disk's index
    hole/timing hole when reading/writing, so the Mitsumi XF551 CAN read
    from, and write to, the reverse side of a disk in single-sided (90KiB,
    130KiB, or 180KiB) mode if the disk is inserted into the drive upside-
    down ("flippy" disk with second index hole/timing hole not needed).
    - Chinon XF551 (Chinon FZ-502 mechanism) (uncommon/rare late production units)
    - Disk Busy light is round, red, and is located directly to the left of the
    "non-straight" drive-latch.
    - http://www.atarimax.com/jindroush.atari.org/data/hardpics/xf551__f.jpg
    - Opening the drive latch causes an inserted disk to be ejected.
    - When a disk is inserted, the drive motor briefly spins and the Disk Busy
    light flashes accordingly.
    - Unlike the Atari 810 and 1050, the Chinon XF551 utilizes the disk's index
    hole/timing hole when reading/writing, so the Chinon XF551 CANNOT read
    from, nor write to, the reverse side of a disk in single-sided (90KiB,
    130KiB, or 180KiB) mode if the disk is inserted into the drive upside-
    down (unless the disk is a "flippy" disk with a second index hole/timing
    hole corresponding to the reverse side).

    Unlike the Atari 810 and 1050, the XF551 (both Mitsumi and Chinon) utilizes
    the disk's index hole/timing hole when formatting the disk. As a result, the XF551 CANNOT format the reverse side of a disk in single-sided (90KiB, 130KiB, or 180KiB) mode if the disk is inserted into the drive upside-down (unless the disk is a "flippy" disk with a second index hole/timing hole corresponding to the reverse side).

    The XF551 disk drive is used with an external 9 volt AC transformer power supply rated for at least 50 watts; Atari CA017964 or equivalent.

    The XF551 shipped with DOS 2.5 (1987-1988) or DOS XE (from 1989).

    Manuals:
    - Atari DOS 2.5: XF551 Disk Drive Owner's Manual C033537
    - Atari DOS XE: XF551 Disk Drive Owner's Manual C300557

    The key engineer/designer of the XF551 was Jose Valdes at Atari.

    Third-party upgrades for the XF551:

    XF35 Kit, by Innovative Concepts, 1988-11-11
    - Developed by Bob Woolley
    - A standard 3.5" 720KiB drive mechanism (not included with Kit) may replace
    the 5.25" drive of the XF551, or it may be added to the drive making it
    possible to select one or the other using a toggle switch.
    - Dual drive option requires several additional parts, not included with Kit
    - Kit also includes replacement drive ROM: (thanks Bob Woolley for details)
    - Changes the number of tracks to 80,
    - Tweaks the track seek timing to match a typical 3.5,
    - Adds (or deletes) spin-up delay that improves write reliability, and
    - Provides for density retry.
    - XF551 high speed remains available

    XF Single Drive Upgrade, by Computer Software Services (CSS), 1991
    -- Replace the 5.25" drive mechanism with a 3.5" drive mechanism
    -- US Doubler compatible/UltraSpeed capable
    -- Can read:
    - 3.5" SS-DD MS-DOS format 360KiB floppy disks
    - 3.5" DS-DD MS-DOS format 720KiB floppy disks
    - Shipped with IBM/ST Transfer Utility disk, containing IBMREAD.COM http://www.nleaudio.com/css/products/XFsingdrup.htm

    XF Dual Drive Upgrade, by Computer Software Services (CSS), 1991
    - Same as XF Single Drive Upgrade, except keep using the XF551 5.25" drive as
    well. Result is two disk drives; the new 3.5" drive assumes the next drive
    number higher than the 5.25" drive. http://www.nleaudio.com/css/products/XFdualdrup.htm

    XF551 Enhancer
    - By Computer Software Services (CSS)
    - Provides a switch that allows the XF551 to read/write/format, in single-
    sided mode, the back side of a disk that has only one index hole/
    timing hole corresponding to the front side of the disk.
    - No need for the disk to have a second write protect hole.
    - A write protect disable is built in.
    - 60Hz version for North America or 50Hz version for Europe http://www.nleaudio.com/css/products/XF551enh.htm

    XF Update
    - By Computer Software Services (CSS), 1992
    - Replacement drive operating system (ROM)
    - "Runs more commercial software"
    - Changes density properly
    - US Doubler compatible/UltraSpeed capable
    - Improved/optimized interleave in high speed formats
    - Can read:
    - 5.25" SS-DD MS-DOS format 180KiB floppy disks
    - 5.25" DS-DD MS-DOS format 360KiB floppy disks
    - Shipped with IBM/ST Transfer Utility disk, containing IBMREAD.COM http://www.nleaudio.com/css/products/XFupdate.htm

    XF Speedy
    - (c) 1994 Klaus Peters Elektronik + Software
    - Converts drive to a Speedy 1050 clone with a DSDD 360KiB mode
    - Replaces the 8040 MPU with a 65C02 + ROM + Memory

    Hyper-XF (or HyperXF)
    - (c) 1998 Stefan Dorndorf
    - Replacement drive operating system (ROM)
    - Hyper-XF 1.0A is for original XF551 with 5.25" drive
    - Hyper-XF 1.0B is for the XF551 with replacement 3.5" drive installed
    - US Doubler compatible/UltraSpeed capable
    - "Hyper Speed" is an UltraSpeed support routine in ROM
    - Allows the drive to support UltraSpeed using DOS versions that
    otherwise lack such support
    - XF551 standard high speed is removed
    - Can use disk partitions (2 on 5.25", 4 partitions on 3.5") with mixed
    Densities (S/E/D) or standard 360KiB (5.25") / 720KiB (3.5")
    - Can theoretically read/write ST/PC 720KiB disks (software is missing!)
    - Improved double density detection http://atariage.com/forums/topic/84017-xf551/#entry1023935

    Reimaged XF551 Disk Drive Controler
    - By Bits of the Past (Dropcheck / Lenore Underwood), 2014
    - With Modern Power Supply or with Original Power Supply http://www.bitsofthepast.com/

    ------------------------------

    Subject: 3.2.4) What were the Atari 815, XF521, and XF351 Disk Drives?

    The 815 Dual Disk Drive was introduced by Atari in June 1980 at the Summer Consumer Electronics Show (CES) in Chicago. The unit would feature two single-sided, double density (MFM encoding) disk drives. The 815 would not have a single density (810-compatible) operation mode (a shortcoming that
    would inspire Percom to invent the "Percom configuration block" as a standard for density-configurable Atari disk drives).
    - Total storage capacity per diskette:
    40 tracks x 18 sectors/track = 720 sectors/disk
    720 sectors x 256 bytes/sector = 184,320 bytes/disk (180KiB)
    - While most 815 sample drives utilized the same Tandon drive mechanism found
    in late-production Atari 810 drives, there were also 815 sample drives built
    that used the MPI drive mechanism found in earlier 810 drives (including all
    810 drives manufactured while the 815 was under development).
    - Manual: Atari 815 Operator's Manual C016377 (CO16377)
    - The 815 disk drive has a built-in power supply (plugs directly into the
    wall, 120V AC).
    - 815 accessories from Atari:
    o CX8201 Master Diskette II
    (DOS II version 2.0D, or DOS 2.0D; version of DOS II supporting both 815
    and 810 disk drives; prototype box exists, but never shipped)
    o CX8202 5 Blank Diskettes
    Box contains five CX8202 Atari 810/815 Blank Diskettes (certified for
    double density use).
    Minimal production, see: http://www.myatari.com/ebay/815dt.html
    - Atari continued to promote the 815 through the summer of 1981 (see Company
    Store price list for 8-24-81 for a late reference); it was dropped from
    the product line by October 1981. Prototype units exist (according to
    Atarimuseum.com: 60 units were produced), but the 815 never shipped.
    http://www.atarimuseum.com/computers/8BITS/400800/815/815.html

    The XF521 5.25" disk drive was previewed by Atari in January 1985 at the
    Winter CES in Las Vegas. The XF521 was to be a 130KiB, XE-styled, feature- equivalent, and gradual replacement for the Atari 1050. The XF521 never shipped, and no more than a handful of prototype units may exist.
    Pictures: http://www.atari-computermuseum.de/pics/zubehoer/xe/xf521.jpeg
    http://www.rhod.fr/ataripics/Xf521_xegs.jpg

    The XF351 3.5" single-sided double density disk drive was first previewed by Atari in March 1986 at CeBIT in Hanover, West Germany. The XF351 was subsequently previewed at the 1986 Spring COMDEX show in Atlanta and at the January 1987 Winter CES in Las Vegas. With ADOS (would ship as: DOS XE), the XF351 was reported to provide 325KiB (6/1986 report) or 320KiB (9/1986 report) of storage (formatted) per disk. The XF351 never shipped, and no more than a handful of prototype units exist.
    Picture: http://www.atari-computermuseum.de/pics/zubehoer/xe/xf351.jpg Discussion: http://atariage.com/forums/topic/231674-xf351-for-sale-on-ebay/

    ------------------------------

    Subject: 3.2.5) What other floppy disk drives were designed for my Atari?

    Major contributors to this section: Glenn M. Saunders, Tomasz M. Tatar,
    James Bradford, Konrad M. Kokoszkiewicz, Don Schoengarth, Andreas
    Koch, TXG/MNX

    This section attempts to comprehensively list released 3rd-party floppy disk drives designed for use with the Atari. These attach to the computer via SIO and generally include two Atari SIO ports, unless stated otherwise. Top transfer rate is 19.2 kbit/s unless stated otherwise. Media requirements, unless stated otherwise, are the same as for the Atari 810.

    LEGEND
    ======
    SD = Single Density, 5.25" floppy disks, 90KiB/side, 810 compatible
    ED = Enhanced Density, 5.25" floppy disks, 130KiB/side, 1050 compatible
    DD = Double Density, 5.25" floppy disks, 180KiB/side, Percom compatible
    SS = Single-Sided
    Drive has only one drive head, so it can only read/write to one side
    of the disk. The reverse side of a disk may or may not be used by
    inserting the disk upside-down, depending on whether the drive uses
    or ignores the index hole/timing hole, and whether the disk is a
    (rare) "flippy" disk with two index holes/timing holes.
    DS = Double-Sided
    The following information is mostly taken from the documentation for
    HiassofT's WriteAtr program, http://www.horus.com/~hias/atari/
    Double-Sided drives for the Atari may use one of three different
    drive-mapping possibilities.
    * Most double-sided Atari disk drives:
    First fill tracks 0-39 (or 0-79) on the first side, then switch
    over to side 2 and again fill tracks 0-39 (0-79 for 3.5" disks).
    * The XF551 first fills track 0 on the first side. Then it
    fills track 1, then track 2, ... up to track 39 (on a 5.25" disk)
    or 79 (on a 3.5" disk). Then it switches to side 2 and fills
    the disk in reverse order (starting at track 39/79, then 38/78,
    ... til it has reached the end of the disk at track 0).
    * The third possibility is the standard in the PC world, but on the
    Atari it's possibly unique to drives connected via the Karin Maxi
    interface.
    If your Atari disk drive uses this mapping, it first fills
    track 0 on side 1, then track 0 on side 2, then seeks to track 1,
    again first fills track 1 / side 1, then track 1 / side 2,
    and so on, until it finishes with track 39 (79) / side 2.
    The drive switches the heads (sides) first before switching
    the track.
    * The TRAK AT-D4 (uniquely?) functions as two logical drives, where
    the second "drive" (side) is read/written in reverse order.

    Amdek AMDC-II SS SD/ED/DD dual drives. Media is 3-inch (3.0")
    Compact Floppy (CF) standard, 180KiB/side,
    shipped with DOS XL
    SN-360 DS SD/ED/DD. 8051 processor, WD2797 controller
    by Atari Studio AS (later, Mirage)
    Astra 1620 SS SD/DD dual drives.
    Shipped with OS/A+ Version 2 or DOS XL
    Astra 2001 SS SD/DD dual drives. Replaced the Astra 1620.
    Shipped with SmartDOS.
    Astra "Big D" DS SD/DD dual drives. Shipped with MYDOS 3.016 (earlier
    units) or Top-DOS 1.5 (later units).
    Astra The "One" DS SD/DD. Shipped with Top-DOS 1.5.
    Astra 1001 SS SD/DD. Shipped with SmartDOS.
    B&C 810 SS SD (B&C ComputerVisions house version of Atari 810) California Access CA-2001 by LDW, 1988 replacement for LDW Super 2000 (Poland)
    SS SD/ED/DD, Indus GT compatible/Synchromesh capable,
    Sold with DOS XL 2.35I1 (manual: "DOS XL 2.35L")
    Upgrades:
    - TOMS Turbo Drive LDW (1989)
    - SS DD IBM:40 tracks * 9 sectors * 512 bytes = 180KiB
    - 1050 Turbo compatible/Turbodrive capable,
    - Synchromesh support removed
    - Software: Turbo Kopier, Track Copier,
    Chaos Initializer, IBM DOS, IBM 360
    - TOMS Multi Drive LDW (1990)
    - Same as TOMS Turbo Drive LDW but also Happy
    Enhancement compatible/Warp Speed capable, and
    1050 Duplicator compatible, and with more software:
    Track Master, Tracer, Index Formatter, Get Track,
    Index Get Track, Bad Formatter, Weak Writer,
    Put Track, Hex Editor
    - Atares Flash system (1991)
    - SS DD IBM:40 tracks * 9 sectors * 512 bytes = 180KiB
    - Unique: 40 tracks * 6 sectors * 1024bytes = 240KiB
    - "Flash Turbo" high speed 127 kbit/s
    - Supplied with FlashDOS
    - SRAMCharger by trub, http://trub.atari8.info/
    Concorde C-221M SS SD/DD; single SIO port - must be at end of SIO
    chain; shipped with DOS XL; see Analog #23 p12.
    Rare pics: https://preview.tinyurl.com/y7uogwos
    Concorde C-222M DS SD/DD see Analog #23 p12, released?
    Flop VD 40 F same as Viatronic VD 40 described below but with standard
    Atari SIO ports. http://preview.tinyurl.com/m3mhqp3 Floppy 2000 by Klaus Peters Elektronik & Software
    DS SD/ED/DD Speedy 1050 clone with a DSDD 360KiB mode,
    Copy 2000 program in ROM
    Indus GT by Indus Systems, Inc., 1983-1986
    by Future Systems, Inc., 1986-1987
    SS SD/ED/DD, Z-80A MPU, early units shipped with OSS
    DOS XL 2.20 or 2.30, most units shipped with Synchromesh
    (DOS XL 2.35I1 implementing 38400 bit/s).
    Except early units, shipped with "GT DrivingSystem":
    - GT Estate Wordprocessor, (c) 1983 Elcomp Publishing
    author: H. C. Wagner for IJG, Inc.
    - GT Albert E. Spreadsheet by SIM Computer Products Inc.
    (c) 1982-1983 by David H. Hewit
    - GT Data Manager, (c) 1984 Vervan Software
    authors: Carl M. Evans and Richard M. Leonard
    1986-1987 units (from Future Systems) shipped with
    Synchromesh II (DOS XL 2.35I2 implementing 68200 bit/s)
    and the "GT DrivingSystem" and also:
    - GT Speller for GT Estate Word Processor
    - RAM130 RAM Disk Utility for 130XE
    - INITSYNC.COM - enables Synchromesh during boot up
    Upgrades released by Future Systems in 1986:
    - RAM Charger: 64KiB RAM + Synchromesh II + one of:
    - CP/M 2.2 (including CP/M BIOS) + CP/M Terminal, OR
    - CP/M BIOS (without CP/M 2.2) + CP/M Terminal
    - Synchromesh II (for earlier Indus GT customers)

    [continued in next message]

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Michael Current@21:1/5 to Marc G. Frank on Fri Aug 30 20:27:51 2019
    [continued from previous message]

    from November 1984 to February 1985 (fairly rare), and again in Singapore by Atari-PCI Enterprises Pte. Ltd. from October 1985 to December 1985 (also
    fairly rare).

    1050 drives made in Singapore use a Tandon drive mechanism, while 1050 drives made in Hong Kong use a World Storage Technology (WST) drive mechanism.

    Several different 1050 ROM (Atari part FC100541) versions have been documented by Atari users, with no practical differences among them. 1983 units shipped with Rev J, 1984 Singapore units shipped with Rev K, 1984-1985 Hong Kong units shipped with an alternate version of Rev K, and 1985 Singapore units shipped with Rev L. See: http://atariage.com/forums/topic/156462-1050-roms/?p=3580891

    1983 production units shipped with DOS 2.0S and in North America only, units produced winter 1984 to winter 1985 shipped (worldwide) with DOS 3, and units produced fall 1985 shipped with DOS 2.5.

    Manuals:
    - Atari 1050 Disk Drive Owner's Guide C061509 (6 pages)
    - Atari 1050 Disk Drive Owner's Guide C024321 (international; 37 pages)
    - Atari DOS 2.5: 1050 Disk Drive Owner's Manual C072033
    - Atari 1050 Disk Drive Field Service Manual FD100330
    - REV. 01 October, 1983
    - REV. 03 October, 1985

    Third-party upgrades for the 1050 (grouped by "family") =================================
    Happy 1050 Enhancement, by Happy Computers, Inc. (Richard Adams), 1984
    - Board includes a 6502 microprocessor and a RAM buffer:
    Up to 36 sectors (SD mode: 2 tracks / 4608 bytes)
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - "Happy" Warp Speed standard high speed reads disks up to 500% times faster
    than standard 1050 with any software; supporting software also supports
    buffered fast write with verify
    - Navigate/edit/create nonstandard format disks
    - Warp Speed Software disk included, contains Warp Speed DOS
    (modified Atari DOS 2.0S), Diagnostic, Sector Copier, Happy Backup, Happy
    Compactor, Multi Drive Happy Backup, Tracer
    - (Rev 2 ROM) ICD US Doubler emulation for UltraSpeed software compatibility
    - IBMXFR IBM Transfer Program included, 1988- (Warp Speed Software v. 7.10)
    - Adds SS-DD "IBM format": 40 tracks, 9 sectors of 512 bytes = 180KiB
    - Software sold separately by Happy Computers:
    - Warp Speed DOS XL, including under cartridge, under ROM and Axlon RAM
    versions (modified DOS XL by Optimized Systems Software (OSS))
    - TOP DOS version 1.5, by Eclipse Software
    - Software sold separately:
    - Happy Version Archiver/Editor, by Spartan Software of Minnesota, 1984
    - Also marketed by B&C ComputerVisions as: Scan-It!/1050 Happy, 1987
    - Fuzzy/Phantom Sector Maker, by CSS, 1986 (Antic 9/86p48)
    - Archiver Enhancement, by Computer Software Services (CSS), 1987
    - Super Archiver/Editor 3.0 and The Archiver Tracer
    - Happy Doubler, by Innovative Concepts, 1989
    - US Doubler compatible/UltraSpeed capable (software solution)
    - Ability to configure drives as D5: through D8:
    - Hardware upgrades for Happy 1050 Enhancement:
    o Happy 1050 Controller, by Happy Computers, Inc., 1986
    - Hardware switch to select Happy Fast or Slow mode
    - Hardware switch to control write protection, with LED indicator
    - Write to reverse side of disks without punching holes
    o Imitator Controller, by Innovative Concepts, 1987
    - Hardware switch to select Happy Fast or Slow mode
    - 3-position switch for write protect mode:
    1) As normal, 2) Do not write, and 3) Will write to any disk
    - Two-color LED for write-protect status
    o IC Chip, by Innovative Concepts, 1988-11-11
    - US Doubler compatible/UltraSpeed capable (replacement Happy ROM)
    Happy 1050 Maximizer, by Happy Computers, Inc.
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - Happy 1050 Controller upgrade compatible
    - Maximizer to Enhancement Upgrade available from Happy Computers
    High Speed Board 1050, by Irata Verlag, 1985 (West Germany)
    - Happy 1050 Enhancement clone
    1050 Lazer Enhancement, from Utility House (1986) (UK)
    - Happy 1050 Enhancement clone
    - Shipped with The Lazer Drive Supercharger software from Utility House
    1050 IS Plate, by Innovated Software (Robert Perry), 1986
    - Add-on board includes 6502 and 16KiB RAM buffer. Plugs into 6507 socket.
    - Happy 1050 Enhancement compatible/near-clone
    - Emulation of: IS Doubler, US Doubler, standard 1050, Archiver/810
    (UltraSpeed and Archiver software compatible)
    - System supports up to 16 drives
    - Shipped with 2-sided disk including IS Doubler/US Doubler emulation, high
    speed disk copiers (standard and 130XE versions), file loader, custom disk
    formatter (including bad sectors), track tracer
    - Late units: Software instead built-in on ROM
    - Sold separately for use with early units: ISP Gremlin Grabber
    - Most units shipped with Gremlin Grammer II or Gremlin Grabber III
    Klone, by Computer Software Services (CSS), 1986 (USA)
    - Happy 1050 Enhancement clone
    - Happy Warp Speed Software (pre-7.0) included
    Klone II, by Computer Software Services (CSS), 1987 (USA)
    - Happy 1050 Enhancement clone
    - Happy Warp Speed Software (7.0) included
    Copy Card 7.0, by ????, year ???? (Europe)
    - Happy 1050 Enhancement compatible/near-clone
    Hyper Drive, by Chaos! Computers (UK), 1994
    - Happy 1050 Enhancement clone
    - Shipped with software package (Ver. II): Hyper Fast DOS, Hyper Sector
    Copier, Hyper Back-Up System, US Doubler Emulation, HyperCompaction,
    Diagnostic Tester, Archiver/810 Emulation, Multi Drive Back-Up
    - See review & ad, Page 6's New Atari User #75 pp. 30-37, 39

    US Doubler, by ICD, 1984
    - ROM replacement chip and 128 byte RAM chip; some drives require moving two
    jumpers also
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - "UltraSpeed" standard high speed "54K baud" via sector skewing; supporting
    software required for high speed (initially: SpartaDOS)
    - Many units shipped with ICD SpartaDOS
    SuperMax, by Super Products
    - US Doubler compatible/UltraSpeed capable
    - Add-on board, switch between standard and replacement drive ROM
    IS Doubler, by Innovated Software (Robert Perry), 1985?
    - US Doubler clone

    Warp Drive, from Stocksoft (UK), 1986
    - Add-on control board replaces two chips
    - Back up including most types of bad sectors
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - Shipped with public domain backup software, double density Menu Maker
    - Archiver/810 compatible (Rev 2 and up)
    Super Archiver, by Computer Software Services (CSS), 1987
    - Add-on board, known as: "Super Archiver Mod", "1050 Super Archiver Chip"
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - Archiver/810 compatible; US Doubler compatible/UltraSpeed capable
    - Navigate/edit/create nonstandard format disks
    - Included software: Super Archiver/Editor 3.0, Super Archiver (skew) 3.1,
    Super Archiver Fuzzy Sector Maker, The Archiver Tracer, Super Archiver
    Diagnostic
    - Also sold without software (B&C ComputerVisions)
    - Bit-Writer upgrade sold separately by CSS (1988):
    - Writes bits rather than sectors, for increased copy capabilities
    Super Archiver II, by CSS, 1988
    - Enhanced density version of CSS Super Archiver
    - Sold complete or as a software-only upgrade for CSS Super Archiver
    - Software: Super Archiver/Editor 3.03 (enhanced density), Super Archiver
    Fuzzy Sector Maker (enhanced density), The Archiver Tracer, Super Archiver
    Diagnostic

    Reproducer, by Gardner Computing, 1984
    - Navigate/edit/create nonstandard format disks
    - Software included
    Density Doubler 1050, by Duplicating Technologies (DT), 1986
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - Whole track buffering (18 sectors / 8KiB) "up to three times faster"
    1050 Duplicator, by Duplicating Technologies (DT), 1986
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - Whole track buffering (18 sectors / 8KiB) "up to three times faster"
    - Navigate/edit/create nonstandard format disks (including enhanced density)
    - Includes copying software
    - Sources (Jim Patchell):
    http://www.oldcrows.net/~patchell/atari/duplicator.html
    - CheerUp Upgrade, by Happy Computers, Inc., 1987
    - Changes 1050 Duplicator to Happy 1050 Enhancement software compatible

    1050 Turbo, by Bernhard Engl for Gerald Engl Computertechnik, 1985-1988
    - Hardware includes replacement ROM (no microprocessor; no RAM buffer)
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - "Turbodrive" standard high speed 68200 bit/s ("70000 baud") via sector
    skewing; high speed supporting software NOT necessary for high speed,
    instead supporting software is loaded from drive ROM
    - Software on ROM: Backup Machine II, Magic Formatter, Maintenance Box
    - http://www.strotmann.de/~cas/Infothek/1050Turbo/
    Top Drive 1050, by Ataserw (1987 or 1988)
    - 1050 Turbo clone (ROM by P.Z. Karen, brand of of LDW)
    - Software: TURBO DOS ("TUR-DOS") disk or cartridge. Known versions:
    - TURBO DOS (c) 1989 ver 2.5 (disk?)
    - TUR DOS - (c) 1990 rev 4.0 (cartridge)
    wszelkie prawa JS & ATASERW Tychy
    - Available upgrade project converts to Happy 1050 Enhancement compatible
    - Details here: http://preview.tinyurl.com/npla4t6

    Speedy 1050 (Mini-Speedy), by Compy-Shop, 1986
    - Includes 65C02 microprocessor, 8KiB RAM buffer, 8KiB program ROM space
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - "Speedy" standard high speed; supporting software required for high speed
    - Speedy 1050N: Internal add-on
    - Speedy 1050NE: External add-on
    - Speedy 1050T: Internal add-on with (external) track display
    - Speedy 1050TE: External add-on with track display
    - Above models: Optional hardware switches for write-protect and
    fast/slow mode control
    - Mini-Speedy S: Internal add-on with 8KiB Sector Copy program in ROM
    - Mini-Speedy D: Internal add-on with 8KiB mini-Bibo-DOS in ROM
    - Mini-Speedy DS: Internal add-on with both Sector Copy and mini-Bibo-DOS
    programs in ROM, hardware switch selectable
    - Super-Speedy prototype: equivalent to Mini-Speedy DS plus track display
    and 192KiB RAM buffer, requiring special software support
    - System disk includes: Speedy Test, Sector Copier. Mini-Speedy system disk
    also includes: Speedy Backup, Speed Init, DiskMapper, HSS Copier
    - Sold separately by Martin Reitershan Computertechnik:
    - Turbo-Speedy DC -- Upgrade replaces mini-Bibo-Dos with the company's
    Turbo-DOS XL/XE, also new firmware; 24KiB ROM space total
    Mega Speedy (Guus Assmann & Matthias Reichl, 2014)
    - Out-of-the-box it supports the original 1050, Speedy, Super Speedy,
    a new Mega Speedy, 1050 Turbo and 1050 Duplicator modes.
    - Hardware can also emulate Happy, US Doubler, Super Archiver, and Supermax,
    but you need to provide the ROMs for these upgrades yourself.
    - More info: http://www.realdos.net/MegaSpeedy.html
    - Software and firmware: http://www.horus.com/~hias/megaspeedy/
    - Documentation: http://www.realdos.net/MegaDocs.html

    Tygrys 1050, by Marek Bojarski of Navitron (1988)
    - Version 1.0: US Doubler clone?
    - Version 2.0: US Doubler and 1050 Turbo compatibility?

    TOMS Multi Drive 1050 (1990)
    - Adds single-sided, double density (180KiB) operation (Percom compatible)
    - Adds SS-DD "IBM format": 40 tracks, 9 sectors of 512 bytes = 180KiB
    - Compatibilities: Happy 1050 Enhancement, 1050 Turbo, 1050 Duplicator
    - Software: TOMS Copier, Track Master, Tracer, Get Track, Weak Writer,
    Bad Formatter, Track Writer, IBM DOS, IBM 360, Turbo Drive Kopier

    Other:
    -----
    Protector, by Computer Software Services (CSS), for 810/1050/Indus GT, 1983
    - Includes hardware and software
    - Bad sector generator; also move/rearrange data, scramble directories Silencer, by CSS, for 810/1050, 1984
    - Eliminates loud drive sounds when reading bad sectors
    - Write to both sides of any disk without notching disks
    Over-Write [1050 version], by Computer Support, 1985
    - Write to side 2 of any disk without notching out a hole in the disk
    Bad Sector, by Computer Support, 1985
    - Write bad sectors to any diskette; can back up some protected disks Write-Right, by Duplicating Technologies, 1986
    - Write to both sides of any disk without notching disks
    Electronic Phantom Sector Maker, by CSS, 1987 (Antic 9/87p28)
    - Installs into any drive, no other modification needed
    - Can be combined with other upgrades including Happy 1050 Enhancement,
    Archiver, and Duplicator
    - Make fuzzy/phantom sectors or fuzz portions of sectors
    - Find/Display valid data, CRC errors and phantom sectors
    - Deluxe version: Allows you to switch between CRC and phantom sectors
    without having to readjust hardware module each time
    IC1050 Controller, by Innovative Concepts, 1989
    - 3-position switch for write protect mode:
    1) As normal, 2) Do not write, and 3) Will write to any disk
    - Two-color LED for write-protect status

    ------------------------------

    Subject: 3.2.3) What is the Atari XF551 Disk Drive?

    The Atari XF551 disk drive was introduced in June 1987 as a replacement for
    the 1050 disk drive. The XF551 is fully backward compatible with the 1050, with the addition of two new modes of operation: a true "double density" mode offering 180KiB of data storage per (single-sided) diskette (fully compatible with 3rd party double density drives for the Atari), and a "double-sided
    double density" mode offering 360KiB of data storage per (2-sided) diskette.

    Unlike the 810 or 1050, the XF551 drive has two drive heads, so it can read/write to both sides of a 2-sided floppy disk (in double-sided double density 360KiB disk mode). The 360KiB mode of the XF551 writes "backwards" to the second side of the disk in comparison to the way data would be stored on the reverse side of a disk, inserted into the drive upside-down, in single- sided double density 180KiB mode.

    When working with double-sided double density 360KiB disks, the XF551 is also capable of communicating with the computer at about twice data rate of the earlier Atari 1050 or 810 drives. This XF551 high speed mode is supported by: DOS XE, SpartaDOS X, XDOS, MyPicoDos, Micro-SpartaDOS, SuperDOS, Turbo-DOS, BW-DOS. A patch was also developed for SpartaDOS 3.2d.

    The front of the XF551 features a "Disk busy" indicator light. (Notably,
    there is no power indicator light on the XF551.) The rear of the unit
    includes a power on/off switch, a Power jack, two SIO ("Peripheral") ports,
    and Drive Select DIP switches:
    Left & Right down: Drive 1
    Left down, Right up: Drive 2
    Left up, Right down: Drive 3
    Left & Right up: Drive 4

    More features/specifications of the XF551 disk drive:
    - 8040/8050 MPU. One of:
    - Intel 8050 microcontroller (MCU) @ 8.3333MHz, C070235
    - Intel 8040 microcontroller (MCU) @ 8.3333MHz, CB101393
    - The 8050 has internal ROM space that is not used in the XF551.
    - (Initial Atari and media reports incorrectly indicated a 6507 MPU.)
    - (The DOS XE: XF551 manual incorrectly indicates 18.3333MHz.)
    - Western Digital WD1772 Floppy Disk Controller (FDC) C026028
    - Late production units substituted: Western Digital WD1770
    - SIO Data rate (normal): 19,040 bit/s (NTSC), 18,688 bit/s (PAL)
    (high speed): 38,908 bit/s (NTSC), 38,553 bit/s (PAL)
    - High speed available in DS/DD 360KiB mode operation only
    - Rotation rate: 300 RPM
    Virtually all other Atari-specific drives spin at 288 RPM. This results in
    rare compatibility issues. Specifically, these commercial disks do not load
    in, and can possibly be damaged (!) by the XF551:
    - Flight Simulator II (subLOGIC)
    - Blue Max (Synapse) (I have personally destroyed multiple Blue Max
    disks with the XF551 drive! -mc)
    - Bank Street Writer (Broderbund). Conflicting reports about this one.
    - Boulder Dash II (Databyte release?)
    - Inside (Spektra, 1990?--original Polish version?)
    - Media used is the same as for the Atari 810.

    Operating modes Single Dual Double Double
    Encoding Method FM MFM MFM MFM
    Number of sides 1 1 1 2
    Total tracks 40 40 40 80
    Sectors per track 18 26 18 18
    Bytes per sector 128 128 256 256 (total capacity)
    Total Bytes 92,160 133,120 184,320 368,640 (total capacity)

    The XF551 drive features a horizontal slot with latch bar door mechanism.
    To complete the insertion of a disk, turn the latch bar clockwise ninety degrees. To release the disk, turn the latch counterclockwise.

    XF551 drives were manufactured for Atari in two versions, both made in Japan.
    - Mitsumi XF551 (most units)
    - Earlier production; common in North America and Europe.
    - Disk Busy light is rectangular, green, and is located below the
    "straight" drive latch
    - See: http://farm5.static.flickr.com/4052/4669794021_de721aa12d_b.jpg
    - When the drive latch is opened, an inserted disk stays in place until
    removed manually.
    - Inserting a disk does not cause any drive activity.
    - Like the Atari 810 and 1050, the Mitsumi XF551 ignores the disk's index
    hole/timing hole when reading/writing, so the Mitsumi XF551 CAN read
    from, and write to, the reverse side of a disk in single-sided (90KiB,
    130KiB, or 180KiB) mode if the disk is inserted into the drive upside-
    down ("flippy" disk with second index hole/timing hole not needed).
    - Chinon XF551 (Chinon FZ-502 mechanism) (uncommon/rare late production units)
    - Disk Busy light is round, red, and is located directly to the left of the
    "non-straight" drive-latch.
    - http://www.atarimax.com/jindroush.atari.org/data/hardpics/xf551__f.jpg
    - Opening the drive latch causes an inserted disk to be ejected.
    - When a disk is inserted, the drive motor briefly spins and the Disk Busy
    light flashes accordingly.
    - Unlike the Atari 810 and 1050, the Chinon XF551 utilizes the disk's index
    hole/timing hole when reading/writing, so the Chinon XF551 CANNOT read
    from, nor write to, the reverse side of a disk in single-sided (90KiB,
    130KiB, or 180KiB) mode if the disk is inserted into the drive upside-
    down (unless the disk is a "flippy" disk with a second index hole/timing
    hole corresponding to the reverse side).

    Unlike the Atari 810 and 1050, the XF551 (both Mitsumi and Chinon) utilizes
    the disk's index hole/timing hole when formatting the disk. As a result, the XF551 CANNOT format the reverse side of a disk in single-sided (90KiB, 130KiB, or 180KiB) mode if the disk is inserted into the drive upside-down (unless the disk is a "flippy" disk with a second index hole/timing hole corresponding to the reverse side).

    The XF551 disk drive is used with an external 9 volt AC transformer power supply rated for at least 50 watts; Atari CA017964 or equivalent.

    The XF551 shipped with DOS 2.5 (1987-1988) or DOS XE (from 1989).

    Manuals:
    - Atari DOS 2.5: XF551 Disk Drive Owner's Manual C033537
    - Atari DOS XE: XF551 Disk Drive Owner's Manual C300557

    The key engineer/designer of the XF551 was Jose Valdes at Atari.

    Third-party upgrades for the XF551:

    XF35 Kit, by Innovative Concepts, 1988-11-11
    - Developed by Bob Woolley
    - A standard 3.5" 720KiB drive mechanism (not included with Kit) may replace
    the 5.25" drive of the XF551, or it may be added to the drive making it
    possible to select one or the other using a toggle switch.
    - Dual drive option requires several additional parts, not included with Kit
    - Kit also includes replacement drive ROM: (thanks Bob Woolley for details)
    - Changes the number of tracks to 80,
    - Tweaks the track seek timing to match a typical 3.5,
    - Adds (or deletes) spin-up delay that improves write reliability, and
    - Provides for density retry.
    - XF551 high speed remains available

    XF Single Drive Upgrade, by Computer Software Services (CSS), 1991
    -- Replace the 5.25" drive mechanism with a 3.5" drive mechanism
    -- US Doubler compatible/UltraSpeed capable
    -- Can read:
    - 3.5" SS-DD MS-DOS format 360KiB floppy disks
    - 3.5" DS-DD MS-DOS format 720KiB floppy disks
    - Shipped with IBM/ST Transfer Utility disk, containing IBMREAD.COM http://www.nleaudio.com/css/products/XFsingdrup.htm

    XF Dual Drive Upgrade, by Computer Software Services (CSS), 1991
    - Same as XF Single Drive Upgrade, except keep using the XF551 5.25" drive as
    well. Result is two disk drives; the new 3.5" drive assumes the next drive
    number higher than the 5.25" drive. http://www.nleaudio.com/css/products/XFdualdrup.htm

    XF551 Enhancer
    - By Computer Software Services (CSS)
    - Provides a switch that allows the XF551 to read/write/format, in single-
    sided mode, the back side of a disk that has only one index hole/
    timing hole corresponding to the front side of the disk.
    - No need for the disk to have a second write protect hole.
    - A write protect disable is built in.
    - 60Hz version for North America or 50Hz version for Europe http://www.nleaudio.com/css/products/XF551enh.htm

    XF Update
    - By Computer Software Services (CSS), 1992
    - Replacement drive operating system (ROM)
    - "Runs more commercial software"
    - Changes density properly
    - US Doubler compatible/UltraSpeed capable
    - Improved/optimized interleave in high speed formats
    - Can read:
    - 5.25" SS-DD MS-DOS format 180KiB floppy disks
    - 5.25" DS-DD MS-DOS format 360KiB floppy disks
    - Shipped with IBM/ST Transfer Utility disk, containing IBMREAD.COM http://www.nleaudio.com/css/products/XFupdate.htm

    XF Speedy
    - (c) 1994 Klaus Peters Elektronik + Software
    - Converts drive to a Speedy 1050 clone with a DSDD 360KiB mode
    - Replaces the 8040 MPU with a 65C02 + ROM + Memory

    Hyper-XF (or HyperXF)
    - (c) 1998 Stefan Dorndorf
    - Replacement drive operating system (ROM)
    - Hyper-XF 1.0A is for original XF551 with 5.25" drive
    - Hyper-XF 1.0B is for the XF551 with replacement 3.5" drive installed
    - US Doubler compatible/UltraSpeed capable
    - "Hyper Speed" is an UltraSpeed support routine in ROM
    - Allows the drive to support UltraSpeed using DOS versions that
    otherwise lack such support
    - XF551 standard high speed is removed
    - Can use disk partitions (2 on 5.25", 4 partitions on 3.5") with mixed
    Densities (S/E/D) or standard 360KiB (5.25") / 720KiB (3.5")
    - Can theoretically read/write ST/PC 720KiB disks (software is missing!)
    - Improved double density detection http://atariage.com/forums/topic/84017-xf551/#entry1023935

    Reimaged XF551 Disk Drive Controller
    - By Bits of the Past (Dropcheck / Lenore Underwood), 2014
    - With Modern Power Supply or with Original Power Supply http://www.bitsofthepast.com/

    ------------------------------

    Subject: 3.2.4) What were the Atari 815, XF521, and XF351 Disk Drives?

    The 815 Dual Disk Drive was introduced by Atari in June 1980 at the Summer Consumer Electronics Show (CES) in Chicago. The unit would feature two single-sided, double density (MFM encoding) disk drives. The 815 would not have a single density (810-compatible) operation mode (a shortcoming that
    would inspire Percom to invent the "Percom configuration block" which became a standard for density-configurable Atari disk drives).
    - Total storage capacity per diskette:
    40 tracks x 18 sectors/track = 720 sectors/disk
    720 sectors x 256 bytes/sector = 184,320 bytes/disk (180KiB)
    - While most 815 sample drives utilized the same Tandon drive mechanism found
    in late-production Atari 810 drives, there were also 815 sample drives built
    that used the MPI drive mechanism found in earlier 810 drives (including all
    810 drives manufactured while the 815 was under development).
    - Manual: Atari 815 Operator's Manual C016377 (CO16377)
    - The 815 disk drive has a built-in power supply (plugs directly into the
    wall, 120V AC).
    - 815 accessories from Atari:
    o CX8201 Master Diskette II
    (DOS II version 2.0D, or DOS 2.0D; version of DOS II supporting both 815
    and 810 disk drives; prototype box exists, but never shipped)
    o CX8202 5 Blank Diskettes
    Box contains five CX8202 Atari 810/815 Blank Diskettes (certified for
    double density use).
    Minimal production, see: http://www.myatari.com/ebay/815dt.html
    - Atari continued to promote the 815 through the summer of 1981 (see Company
    Store price list for 8-24-81 for a late reference); it was dropped from
    the product line by October 1981. Prototype units exist (according to
    Atarimuseum.com: 60 units were produced), but the 815 never shipped.
    http://www.atarimuseum.com/computers/8BITS/400800/815/815.html

    The XF521 5.25" disk drive was previewed by Atari in January 1985 at the
    Winter CES in Las Vegas. The XF521 was to be a 130KiB, XE-styled, feature- equivalent, and gradual replacement for the Atari 1050. The XF521 never shipped, and no more than a handful of prototype units may exist.
    Pictures: http://www.atari-computermuseum.de/pics/zubehoer/xe/xf521.jpeg
    http://www.rhod.fr/ataripics/Xf521_xegs.jpg

    The XF351 3.5" single-sided double density disk drive was first previewed by Atari in March 1986 at CeBIT in Hanover, West Germany. The XF351 was subsequently previewed at the 1986 Spring COMDEX show in Atlanta and at the January 1987 Winter CES in Las Vegas. With ADOS (would ship as: DOS XE), the XF351 was reported to provide 325KiB (6/1986 report) or 320KiB (9/1986 report) of storage (formatted) per disk. The XF351 never shipped, and no more than a handful of prototype units exist.
    Picture: http://www.atari-computermuseum.de/pics/zubehoer/xe/xf351.jpg Discussion: http://atariage.com/forums/topic/231674-xf351-for-sale-on-ebay/

    ------------------------------

    Subject: 3.2.5) What other floppy disk drives were designed for my Atari?

    Major contributors to this section: Glenn M. Saunders, Tomasz M. Tatar,
    James Bradford, Konrad M. Kokoszkiewicz, Don Schoengarth, Andreas
    Koch, TXG/MNX

    This section attempts to comprehensively list released 3rd-party floppy disk drives designed for use with the Atari. These attach to the computer via SIO and generally include two Atari SIO ports, unless stated otherwise. Top transfer rate is 19.2 kbit/s unless stated otherwise. Media requirements, unless stated otherwise, are the same as for the Atari 810.

    LEGEND
    ======
    SD = Single Density, 5.25" floppy disks, 90KiB/side, 810 compatible
    ED = Enhanced Density, 5.25" floppy disks, 130KiB/side, 1050 compatible
    DD = Double Density, 5.25" floppy disks, 180KiB/side, Percom compatible
    SS = Single-Sided
    Drive has only one drive head, so it can only read/write to one side
    of the disk. The reverse side of a disk may or may not be used by
    inserting the disk upside-down, depending on whether the drive uses
    or ignores the index hole/timing hole, and whether the disk is a
    (rare) "flippy" disk with two index holes/timing holes.
    DS = Double-Sided
    The following information is mostly taken from the documentation for
    HiassofT's WriteAtr program, http://www.horus.com/~hias/atari/
    Double-Sided drives for the Atari may use one of three different
    drive-mapping possibilities.
    * Most double-sided Atari disk drives:
    First fill tracks 0-39 (or 0-79) on the first side, then switch
    over to side 2 and again fill tracks 0-39 (0-79 for 3.5" disks).
    * The XF551 first fills track 0 on the first side. Then it
    fills track 1, then track 2, ... up to track 39 (on a 5.25" disk)
    or 79 (on a 3.5" disk). Then it switches to side 2 and fills
    the disk in reverse order (starting at track 39/79, then 38/78,
    ... until it has reached the end of the disk at track 0).
    * The third possibility is the standard in the PC world, but on the
    Atari it's possibly unique to drives connected via the Karin Maxi
    interface.
    If your Atari disk drive uses this mapping, it first fills
    track 0 on side 1, then track 0 on side 2, then seeks to track 1,
    again first fills track 1 / side 1, then track 1 / side 2,
    and so on, until it finishes with track 39 (79) / side 2.
    The drive switches the heads (sides) first before switching
    the track.
    * The TRAK AT-D4 (uniquely?) functions as two logical drives, where
    the second "drive" (side) is read/written in reverse order.

    Amdek AMDC-II SS SD/ED/DD dual drives. Media is 3-inch (3.0")
    Compact Floppy (CF) standard, 180KiB/side,
    shipped with DOS XL
    SN-360 DS SD/ED/DD. 8051 processor, WD2797 controller
    by Atari Studio AS (later, Mirage)
    Astra 1620 SS SD/DD dual drives.
    Shipped with OS/A+ Version 2 or DOS XL
    Astra 2001 SS SD/DD dual drives. Replaced the Astra 1620.
    Shipped with SmartDOS.
    Astra "Big D" DS SD/DD dual drives. Shipped with MYDOS 3.016 (earlier
    units) or Top-DOS 1.5 (later units).
    Astra The "One" DS SD/DD. Shipped with Top-DOS 1.5.
    Astra 1001 SS SD/DD. Shipped with SmartDOS.
    B&C 810 SS SD (B&C ComputerVisions house version of Atari 810) California Access CA-2001 by LDW, 1988 replacement for LDW Super 2000 (Poland)
    SS SD/ED/DD, Indus GT compatible/Synchromesh capable,
    Sold with DOS XL 2.35I1 (manual: "DOS XL 2.35L")
    Upgrades:
    - TOMS Turbo Drive LDW (1989)
    - SS DD IBM:40 tracks * 9 sectors * 512 bytes = 180KiB
    - 1050 Turbo compatible/Turbodrive capable,
    - Synchromesh support removed
    - Software: Turbo Kopier, Track Copier,
    Chaos Initializer, IBM DOS, IBM 360
    - TOMS Multi Drive LDW (1990)
    - Same as TOMS Turbo Drive LDW but also Happy
    Enhancement compatible/Warp Speed capable, and
    1050 Duplicator compatible, and with more software:
    Track Master, Tracer, Index Formatter, Get Track,
    Index Get Track, Bad Formatter, Weak Writer,
    Put Track, Hex Editor
    - Atares Flash system (1991)
    - SS DD IBM:40 tracks * 9 sectors * 512 bytes = 180KiB
    - Unique: 40 tracks * 6 sectors * 1024bytes = 240KiB
    - "Flash Turbo" high speed 127 kbit/s
    - Supplied with FlashDOS
    - SRAMCharger by trub, http://trub.atari8.info/
    Concorde C-221M SS SD/DD; single SIO port - must be at end of SIO
    chain; shipped with DOS XL; see Analog #23 p12.
    Rare pics: https://preview.tinyurl.com/y7uogwos
    Concorde C-222M DS SD/DD see Analog #23 p12, released?
    Flop VD 40 F same as Viatronic VD 40 described below but with standard
    Atari SIO ports. http://preview.tinyurl.com/m3mhqp3 Floppy 2000 by Klaus Peters Elektronik & Software
    DS SD/ED/DD Speedy 1050 clone with a DSDD 360KiB mode,
    Copy 2000 program in ROM
    Indus GT by Indus Systems, Inc., 1983-1986
    by Future Systems, Inc., 1986-1987
    SS SD/ED/DD, Z-80A MPU, early units shipped with OSS
    DOS XL 2.20 or 2.30, most units shipped with Synchromesh

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