• Atari 8-Bit Computers: Frequently Asked Questions (18/29)

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

    - BASIC Reference Manual (400/800/1200XL ed.), C061456 / BX4211, (c)1983,
    126 pages
    - Atari BASIC Reference Guide For Experience Programmers, C061570, (c)1983,
    14 pages
    - Atari BASIC Reference Guide, C061948, (c)1983 (international; 61 pages)

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

    Subject: 7.2.2) How do I load/run or save an Atari BASIC program on cassette?

    To load and run an Atari BASIC program from cassette:
    1. Insert the cassette into the recorder.
    2. Use REWIND or ADVANCE/F.FWD on the recorder, if necessary, to bring the
    tape to the position where the program is located.
    3. Boot the computer to the Atari BASIC READY prompt.
    4. There are several possibilities for the next step, depending on how the
    program was saved, and whether you want to run the program or just load
    it into RAM. Enter one of the following four commands:
    a. CLOAD loads programs saved with CSAVE
    b. LOAD "C:" loads programs saved with SAVE "C:"
    c. ENTER "C:" loads programs saved with LIST "C:"
    d. RUN "C:" loads and runs programs saved with SAVE "C:" 5. The system buzzer sounds (to signal you to press PLAY on the recorder).
    6. Press PLAY on the recorder.
    7. Press the RETURN key on the computer keyboard.
    Tape motion starts, the program loads from the cassette into RAM, and then
    tape motion stops.
    Then, if you entered RUN "C:" above, the loaded program runs; otherwise a
    READY prompt is displayed.
    8. You may press STOP on the recorder once the program is loaded, unless the
    program is designed to control further tape motion start/stop.
    9. If the loaded program is not running yet (you did not enter RUN "C:"
    above), now enter the command: RUN

    To save an Atari BASIC program from computer RAM to cassette:
    1. Insert a cassette into the recorder.
    2. Use REWIND or ADVANCE/F.FWD on the recorder, if necessary, to bring the
    tape to the position where the program is to be recorded.
    3. Enter one of the following three commands:
    a. CSAVE
    (short inter-record gap - fastest read/write speed - tokenized files)
    b. SAVE "C:"
    (long inter-record gap - middle read/write speed - tokenized files)
    c. LIST "C:"
    (long inter-record gap - slowest read/write speeds - straight ATASCII -
    tape actually stops in between block reads/writes)
    4. The system buzzer sounds twice (to signal you to press both PLAY and
    RECORD on the recorder).
    5. Press both PLAY and RECORD on the recorder.
    6. Press the RETURN key on the computer keyboard.
    Tape motion starts, the program is copied from RAM to the cassette, and
    then tape motion stops.
    7. You may press STOP on the recorder once recording has finished.

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

    Subject: 7.3.1) What is Atari DOS, and what versions did Atari release?

    This FAQ section describes the various DOS versions produced by Atari for use with their 8-bit computers: DOS I, DOS 2.0S, DOS 3, DOS 2.5, DOS XE, DOS XLE

    On the Atari, a complete Disk Operating System (DOS) consists of a complex, flexible combination of software components provided in the Atari OS on ROM with software components loaded into RAM from disk:

    1) SIO (Serial I/O bus Utility) routine
    - Component of the Atari OS
    - Generalized low level communications with SIO bus devices, including
    disk drives
    - Utilized by the Resident Diskette Handler
    - Normally utilized by the FMS
    2) Resident Diskette Handler
    - Component of the Atari OS
    - Utilizes SIO for communications with disk drives
    - Supports just five functions (four on the 400/800):
    1. GET SECTOR
    - Read a specified sector
    2. PUT SECTOR WITH VERIFY
    - Write sector; check sector to see if written
    3. STATUS REQUEST
    - Ask the disk controller for its status
    4. FORMAT
    - Issue a format command to the disk controller
    5. PUT SECTOR WITHOUT VERIFY
    - Write sector (don't check sector to see if written)
    - Available on XL/XE; not available on 400/800
    - 400/800: Uses 128 byte sectors
    XL/XE: Can read/write disk sectors having variable length from 1 to
    65536 bytes. Default=128 bytes
    - Normally only used to load the FMS from disk. Exception: Atari DOS I
    uses the OS-resident Diskette Handler for all disk communications.
    3) FMS (File Management Subsystem)
    - Must be loaded from disk (using the Resident Diskette Handler)
    - Normally utilizes SIO for disk drive communications
    - Does not utilize the Resident Diskette Handler. Exception: Atari
    DOS I uses the OS-resident Diskette Handler for all disk
    communications.
    - Normally provides a D: Disk File Manager device handler that is
    compatible with CIO
    4) CIO (Central Input/Output Utility) routine
    - Component of the Atari OS
    - Generalized high level, device independent access to device handlers,
    including any disk drive device handler provided by a FMS
    5) DUP (Disk Utility Package) or equivalent software program(s)
    - Optionally provided with a FMS
    - Must be loaded from disk using the FMS
    - Typically a DOS menu program, but could take any form of software
    that provides a user interface to FMS management functions
    - Normally utilizes CIO for carrying out disk management operations

    In practice, those DOS components loaded into memory from disk, that is, a FMS and any additional programs distributed with that FMS (such as a DUP), are normally collectively described as a "DOS" on the Atari.

    DOS I
    -----
    DISK OPERATING SYSTEM 9/24/79 COPYRIGHT 1979 ATARI
    - Contains two main parts:
    - A File Managememt Subsystem (FMS)
    - Developed by Paul Laughton (also wrote: Atari BASIC) for Shepardson
    Microsystems, Inc. (SMI) for Atari
    - A Disk Utility Package (DUP)
    - Shipped with 810 disk drives manufactured from 1980-1981.
    - Disk Utility Package (DOS menu) is loaded into memory with the FMS
    - Uses the OS-resident Diskette Handler for all disk communications via SIO
    - Disk drive type supported: Atari 810 (& compatible)
    - Disk utilization/filesystem: "DOS I"
    - 128 total bytes/sector, with 3 bytes of each sector used to address
    the next sector
    - 40 tracks * 18 sectors/track = 720 total sectors, with 11 sectors used
    for software control or unused by the FMS.
    - Data capacity per diskette:
    709 sectors x 125 bytes/sector = 88,625 bytes/disk
    - Cannot read disks written with DOS II, which require a 3 sector boot
    - 11 special sectors:
    1 Boot sector, containing the boot record accessed by the Atari OS
    at system power-up
    360 Volume Table of Contents (VTOC) (sector usage)
    361-368 File Directory (8 directory entries per sector)
    720 unused by the FMS (FMS interprets the VTOC sector bit map as
    sectors numbered 0-719, ignoring nonexistant sector 0, while the
    Atari 810 drive uses sectors numbered 1-720)
    - Maximum of 64 files per diskette (8-sector File Directory)
    - Uses binary file format unsupported by any other DOS version for the Atari
    - D: Disk File Manager supports up to four 810 disk drives, D1: through D4:
    - To configure DOS I for fewer drives (freeing system environment RAM),
    adjust memory location 1802 ($70A or DRVBYT):
    1. Boot the system to the BASIC READY prompt
    2. Enter one of:
    - POKE 1802,1 (for a one drive system; saves 397 bytes)
    - POKE 1802,3 (for a two drive system, saves 258 bytes)
    - POKE 1802,7 (for a three drive system, saves 130 bytes)
    - POKE 1802,15 (for a four drive system; DOS I default value)
    3. Go to DOS and use menu item H (WRITE DOS FILE) to write the DOS.SYS
    file (with the new value of location 1802) to disk, replacing any
    existing copy of DOS on that disk.
    - Can open up to 3 files simultaneously
    - Configurable by adjusting memory location 1801 ($709 or SABYTE) via
    the same process as described for adjusting the number of disk drives.
    Valid values for DOS I are 1-3 inclusive. Default is 3.
    - AUTO.SYS can be used to automatically poke data in RAM locations on
    system startup.
    - Files copied or duplicated in small buffer
    - Must redisplay menu before issuing new command
    - Can only write DOS system file to drive 1
    - N. DEFINE DEVICE menu option: "The full implementation of this selection is
    not supported, so use it with caution." --DOS Reference Manual p.39
    - DOS I is not compatible with the 850 Interface Module R: device handler
    - Disk File Manager Master Copy (CX8101) disk contains:
    DOS.SYS both the FMS with D: Disk File Manager and DUP with DOS Menu,
    loaded by OS-resident Diskette Handler on system startup
    - Manual: Disk Operating System Reference Manual C015200

    DOS 2.0S
    --------
    DISK OPERATING SYSTEM II VERSION 2.0S COPYRIGHT 1980 ATARI
    - Shipped with 810 and 1050 disk drives manufactured from 1981-1983.
    Master Diskette also shipped with the Atari Touch Tablet.
    - FMS (DOS.SYS) component developed by Paul Laughton for Shepardson
    Microsystems, Inc. (SMI) for Atari, based on the Atari DOS I FMS.
    Released code version: "19-Aug-80"
    - Disk Utility Package (DUP.SYS -- DOS menu) is separate from the FMS, and
    optional for use of the FMS, freeing up memory for user programs when the
    DUP is not needed. Released code version: "ver 2.9 11/18/80"
    - Does not use the OS-resident Diskette Handler once the FMS is loaded.
    - Utilizes SIO for disk drive communications
    - MEM.SAV file can be employed to preserve the contents of memory to disk
    when DUP.SYS is loaded.
    - Introduces support for AUTORUN.SYS binary file launch upon system boot
    (replaces AUTO.SYS of DOS I)
    - Disk drive type supported: Atari 810 (& compatible)
    - Disk utilization/filesystem: "DOS 2.0 Single Density"
    - 128 total bytes/sector, with 3 bytes of each sector used to address
    the next sector
    - 40 tracks * 18 sectors/track = 720 total sectors, with 13 sectors used
    for software control or unused by the FMS.
    - Data capacity per diskette:
    707 sectors x 125 bytes/sector = 88,375 bytes/disk
    - Requires a 3 sector boot (provision for double density version DOS 2.0D)
    - 13 special sectors:
    1-3 Boot sectors, containing the boot record accessed by the Atari
    OS at system power-up
    360 Volume Table of Contents (sector usage)
    361-368 File Directory (8 directory entries per sector)
    720 unused by the FMS (same as DOS I)
    - Maximum of 64 files per diskette (8-sector File Directory)
    - Difference in boot record lengths means DOS I and DOS II disks cannot be
    interchanged.
    - Established standard binary file format supported by ALL other DOS versions
    for the Atari (exception: Atari DOS I)
    - By default, the CIO-compatible D: Disk File Manager supports up to two 810
    disk drives, D1: and D2:
    - To configure DOS 2.0S for the number of 810 disk drives attached to the
    system (which affects system environment RAM), adjust memory location
    1802 ($70A or DRVBYT):
    1. Boot the system to the BASIC READY prompt
    2. Enter one of:
    - POKE 1802,1 (D1:)
    - POKE 1802,3 (D1: and D2: -- DOS 2.0S default value)
    - POKE 1802,7 (D1:, D2:, D3:)
    - POKE 1802,15 (D1:, D2:, D3:, D4:)
    - POKE 1802,31 (D1:, D2:, D3:, D4:, D5:)
    - POKE 1802,63 (D1:, D2:, D3:, D4:, D5:, D6:)
    - POKE 1802,127 (D1:, D2:, D3:, D4:, D5:, D6:, D7:)
    - POKE 1802,255 (D1:, D2:, D3:, D4:, D5:, D6:, D7:, D8:)
    3. Go to DOS and use menu item H (WRITE DOS FILES) to write the DOS
    system files (with the new value of location 1802) to disk,
    replacing any existing copy of DOS on that disk.
    - By default, can open up to 3 files simultaneously
    - Configurable by adjusting memory location 1801 ($709 or SABYTE) via
    the same process as described for adjusting the number of disk drives.
    Valid values for DOS 2.0S are 1-7 inclusive. Default is 3.
    - Files copied or duplicated into buffer which can be as large as user memory
    area
    - SAVE BINARY FILE has "/A" option allowing two files to be appended together
    - Can create load-and-go type file which enables you to select a file and
    have it automatically run without entering a RUN address
    - Diskette with bad sectors detected cannot be formatted
    - Screen margins are reset when DUP is entered
    - DUP: May enter another command or resdisplay menu after a command
    - Can write DOS files to any drive
    - NOTE/POINT are available for random file access
    - Atari 810 Master Diskette II or Atari 810/1050 Master Diskette II (CX8104)
    disk contains:
    DOS.SYS FMS with D: Disk File Manager, loaded by OS-resident
    Diskette Handler on system startup
    DUP.SYS Disk Utility Package (DOS menu)
    AUTORUN.SYS Loads the R: device handler from an 850 Interface Module
    - Shipped with one Atari CX8111 Formatted Diskette II
    - Manuals:
    - Disk Operating System II Reference Manual C016347
    - Disk Utilities Listing, February 1981 C016558 (without binder)
    (DUP.SYS source code, early release)
    - DOS Utilities Source Listing (DOS II), August 1981 C017894
    ("Disk Utility Programs (DUP) ver 2.9 11/18/80")
    - Atari 810 Disk Drive: An Introduction to the Disk Operating System
    C060054 (CO60054)
    - Atari 1050 Disk Drive: An Introduction to the Disk Operating System
    C061529
    - On February 25, 1981, the source code to the Atari DOS 2.0S FMS (DOS.SYS)
    was purchased from SMI by Optimized Systems Software (OSS), headed by
    former SMI employees Bill Wilkinson and Mike Peters.
    - Inside Atari DOS (Compute! Books, 1982, 0-942386-02-7), authored by
    Bill Wilkinson, made the source code to the Atari DOS 2.0S FMS (DOS.SYS)
    available to the public. See: http://www.atariarchives.org/iad/
    - Modified versions of DOS 2.0S were widely created and exchanged among Atari
    users. Also notably, the first 3rd-party disk drive for the Atari, the
    Percom RFD40-S1, was initially (1982) distributed with a program ("BLD")
    to build Percom DOS 2.0P (double density support) from a copy of DOS 2.0S.

    DOS 3
    -----
    Atari DOS 3 Copyright 1983
    - Shipped with 1050 disk drives manufactured from 1984 through early 1985.
    - Developed by 3-person team at Atari, led by Richard K. (Hud) Nordin
    - Project started at Atari by early 1981 under systems software manager
    Brian Johnston. Contributor: NEOTERIC consultant Harry B. Stewart
    - Disk drive types supported:
    1) Atari 810 (& compatible)
    2) Atari 1050 (& compatible)
    3) Atari 1450XLD built-in (double-sided, enhanced/dual density)
    Minimal support only: A single 1450XLD disk drive appears to DOS 3 as
    two Atari 1050 drives. That is, side 1 is accessed as D1: and side 2
    is accessed as D2:.
    - Disk utilization/filesystems:
    1) "DOS 3 Single Density"
    - Sector = 128 bytes
    - Block = 8 sectors = 1024 bytes
    - Track = 18 sectors = 2304 bytes
    - Disk contains 40 tracks, or 720 sectors, or 90 blocks, with 3 blocks
    used for software control.
    - Data capacity per diskette:
    87 blocks x 1024 bytes/block = 89,088 bytes/disk
    - Blocks 1-3 are used by the system as 24 special sectors:
    1-9 Boot sectors, containing the boot record accessed by the
    Atari OS at system power-up
    10-15 unused
    16-23 File Directory
    24 File Allocation Table (block usage)
    - Maximum of 63 files per diskette (8-sector File Directory)
    2) "DOS 3 Double Density" (enhanced/dual density)
    - Sector = 128 bytes
    - Block = 8 sectors = 1024 bytes
    - Track = 26 sectors = 3328 bytes
    - Disk contains 40 tracks, or 1040 sectors, or 130 blocks, with 3
    blocks used for software control.
    - Data capacity per diskette:
    127 blocks x 1024 bytes/block = 130,048 bytes/disk
    - Blocks 1-3 are used by the system as 24 special sectors:
    1-9 Boot sectors, containing the boot record accessed by the
    Atari OS at system power-up
    10-15 unused
    16-23 File Directory
    24 File Allocation Table (block usage)
    - Backward compatible with DOS 3 Single Density
    - Maximum of 63 files per diskette (8-sector File Directory)
    - Keyboard Command Processor (KCP) is separate from the FMS, and optional for
    use of the FMS, freeing up memory for user programs when the KCP DOS
    subfunctions and the DOS menu are not needed.
    - KCP Overlay (DOS menu) is separate from the FMS and KCP, and optional for
    use of the FMS and KCP, freeing up memory for user programs when the DOS
    menu is not needed.
    - MEM.SAV file can be employed to preserve the contents of memory to disk
    when the KCP Overlay (DOS menu) is loaded.
    - Supports AUTORUN.SYS binary file launch upon system boot
    - File manager and buffers now take up less space than the DOS 2 equivalents.
    All utilities, such as COPY, INIT, DUPLICATE (all UTL files) are called
    into memory only as needed. Each is maintained in a separate file.
    - Provides a direct method for the user to modify the FMS parameters
    - Provides an online HELP feature
    - Compared to DOS 2: The NOTE and POINT commands return a pointer number
    relative to the start of a file (byte 0) rather than an absolute sector and
    byte location within the sector.
    - Master Diskette 3 (DX5052) contains:
    FMS.SYS FMS with D: Disk File Manager, loaded by OS-resident
    Diskette Handler on system startup. Contains subfunctions:
    ERASE FILE, RENAME FILE, PROTECT FILE, UNPROTECT FILE, LOAD
    KCP.SYS Keyboard Command Processor, loaded on system startup if a
    cartridge is present. Contains subfunctions: SAVE,
    GO AT HEX ADDRESS, TO CARTRIDGE, COPY FILE, INIT DISK,
    DUPLICATE DISK, ACCESS DOS 2
    KCPOVER.SYS KCP Overlay, displays the DOS menu and process commands
    COPY.UTL COPY/APPEND utility
    DUPDISK.UTL DUPLICATE utility
    INIT.UTL INIT Disk utility
    CONVERT.UTL ACCESS DOS 2 utility, use to copy files from a DOS 2.0S disk
    to a DOS 3 disk
    HELP.UTL HELP utility
    HELP.TXT Text information displayed by the HELP utility
    HANDLERS.SYS Loads the R: handler from an Atari 850 Interface Module
    during system boot up, if this file is on the drive 1
    diskette.
    - Manuals for DOS 3:
    - Atari Disk Operating System Reference Manual C062287 (100 pages)
    (makes no mention of the 1450XLD built-in disk drive(s))
    - An Introduction to the Atari Disk Operating System C062288 (29 p)
    (makes extensive mention of the 1450XLD built-in disk drive(s))
    - Atari DOS 3 Reference Manual Errata, 05/01/84
    "Early versions of DOS 3 used a random access method that was incompatible
    with large files. To determine if you have an early version, boot your
    copy of DOS 3 with Atari BASIC, and execute the following BASIC command:
    PRINT PEEK(1816)
    If the value returned is '53', your copy of DOS 3 is the latest released.
    If the value returned is '51' or '56', Atari Customer Relations offered a
    program to update DOS 3 to the latest revision level."
    - Atari 1050 Disk Drive: An Introduction to the Atari Disk Operating
    System C024323 (international; 144 pages)

    DOS 2.5
    -------
    DISK OPERATING SYSTEM II VERSION 2.5 COPYRIGHT 1984 ATARI CORP.
    - Shipped with 1050 disk drives manufactured in fall 1985, and with XF551
    disk drives manufactured in 1987-1988.
    - Developed by Optimized Systems Software (OSS - Bill Wilkinson) for Atari
    - Disk drive types supported:
    1) Atari 810 (& compatible)
    2) Atari 1050 (& compatible)
    3) Atari 130XE RAMdisk (65,408 bytes)
    - Disk utilization/filesystems supported (detected automatically):
    1) DOS 2.0 Single Density
    2) "DOS 2.5 Enhanced Density" (or just "DOS 2.5")
    - 128 total bytes/sector, with 3 bytes of each sector used to address
    the next sector
    - 40 tracks * 26 sectors/track = 1040 total sectors, with 30 sectors
    used for software control or unused by the FMS.
    - Data capacity per diskette:
    1010 sectors x 125 bytes/sector = 126,250 bytes/disk
    - 30 special sectors:
    1-3 Boot sectors, containing the boot record accessed by the
    Atari OS at system power-up
    360 Volume Table of Contents (sectors 1-719 usage)
    361-368 File Directory (8 directory entries per sector)
    720 unused by the FMS (same as DOS I and DOS 2.0S)
    1024 Extended Volume Table of Contents (sectors 720-1023 usage)
    1025-1040 unused by the FMS (FMS uses a 10-bit sector address)
    - Maximum of 64 files per diskette (8-sector File Directory)
    - Backward compatible with DOS 2.0 Single Density
    3) "DOS 2.5 130XE RAMdisk"
    - 128 total bytes/sector, with 3 bytes of each sector used to address
    the next sector
    - 508 total sectors, with 9 sectors used for software control.
    - Data capacity:
    499 sectors x 125 bytes/sector = 62,375 bytes
    - 9 special sectors:
    360 Volume Table of Contents (sector usage)
    361-368 File Directory
    - Maximum of 64 files (8-sector File Directory)
    - Backward compatible with DOS 2.0 Single Density
    - RAM memory locations 1802 ($70A or DRVBYT, the active drive map) and 1801
    ($709 or SABYTE, the maximum number of concurrently open files) are
    utilized in the same way as by DOS 2.0S.
    - If the DOS 2.5 130XE RAMdisk is enabled, the default value for SABYTE is
    131, enabling D1:, D2:, and D8:, where D8: is the RAMdisk.
    - DOS 2.5 (DX5075) disk contains:
    DOS.SYS FMS with D: Disk File Manager, loaded by OS-resident
    Diskette Handler on system startup
    DUP.SYS Disk Utility Package (DOS menu)
    RAMDISK.COM If present on startup disk on an XL/XE with 128KiB RAM or
    more:
    1) Displays a message that it is initializing the RAMdisk
    2) Sets up a 64KiB RAMdisk as D8:
    3) Copies DUP.SYS to D8: and establishes MEM.SAV on D8:
    SETUP.COM External utility has 3 functional options:
    1) Change current drive number
    2) Change system configuration. 3 configurable options:
    i) Active drives number (1 to 4)
    ii) Max number of simultaneous files (1-7)
    iii) Disk writes with or without verify
    3) Create an AUTORUN.SYS that does either one or both of:
    - Load the R: handler from an Atari 850 Interface Module
    - Load and RUN a BASIC program from the boot disk
    COPY32.COM Utility to copy files from a DOS 3 disk to a DOS 2.5 or to a
    DOS 2.0S disk
    DISKFIX.COM DiskFix Utility can be used to:
    - Unerase a file (under certain circumstances)
    - Verify the soundness of every file on a disk
    - Rename a file by number (solves problem of files with
    duplicate names)
    - Manuals:
    - Atari DOS 2.5: 1050 Disk Drive Owner's Manual C072033
    - Atari DOS 2.5: XF551 Disk Drive Owner's Manual C033537

    DOS XE
    ------
    DOS XE DISK OPERATING SYSTEM COPYRIGHT 1988 ATARI CORP. VERSION 01.00
    - Shipped with late production XF551 disk drives starting in 1989
    - Developed by Bill Wilkinson for Atari. Known as "ADOS" prior to release
    - Requires an XL/XE; does not run on the 400/800
    - Disk Utility Package (DOS menu) is loaded into memory with the FMS
    - Disk drive types supported:
    1) Atari 810 (& compatible)
    2) Atari 1050 (& compatible)
    3) Atari XF551 -- XF551 high speed supported
    4) Atari 130XE RAMdisk (64KiB)
    5) SSDD 5.25" Single-Sided, Double Density
    - Disk utilization/filesystems:
    1) "DOS XE" via the native D: Disk File Manager:
    - Supports disk drive sizes up to 16MiB.
    - Files can be up to 8MiB long.
    - All disks are addressed in 256 byte sectors. Simulates 256 byte
    sectors on 810 and 1050 disk drives, which have 128 byte sectors,
    by reading and writing sector pairs.
    - Up to 65536 sectors can exist on a single disk.
    (65536 sectors x 256 bytes/sector = 16MiB)
    - Five different types of sectors:
    1) Boot sectors
    - Disk sectors 1-3 contain the boot record accessed by the
    Atari OS at system power-up. (OS reads 128 bytes/sector)
    - Contains a 32 byte Drive Table describing the physical and
    logical layout of the disk.
    - The DOS XE 130XE RAMdisk does not have boot sectors.
    2) Volume Table of Contents (VTOC) sectors
    - Starts in sector 4 (one sector only for drive types supported
    by DOS XE).
    - The first 10 bytes give information about the current status
    of the disk and the rest is a bit map of the blocks on the
    disk.
    3) Directory sectors
    - The first directory block immediately follows the VTOC
    sector(s). Additional directory blocks are allocated as
    needed and may be scattered throughout the disk, linked by a
    two-byte pointer at the end of each block.
    - Each entry contains the file name, information about the
    file (including creation date and last modified date), and up
    to 12 two-byte pointers which point to the file map blocks
    for the file.
    - Includes a six byte sector label, containing the File ID
    number, Volume number, and Sequence number.
    4) File Map sectors
    - Contain from 1 to 125 two byte data block pointers.
    - Includes a six byte sector label, containing the File ID
    number, Volume number, and Sequence number.
    5) Data sectors
    - 250 bytes allocated for data.
    - Includes a six byte sector label, containing the File ID
    number, Volume number, and Sequence number.
    2) DOS 2.0 Single Density via the optional DOS 2.x A: Disk File Manager
    3) DOS 2.5 Enhanced Density via the optional DOS 2.x A: Disk File Manager
    - Disk File Managers can address up to eight drives (D1: to D8:, A1 to A8:).
    - A directory or subdirectory can hold up to 1250 files or subdirectories.
    - File pathnames are limited to 80 characters.
    - Hybrid interface is both menu driven and command driven, including stacked
    command entry.
    - Batch files can be used to automate tasks;
    AUTOEXEC.BAT run automatically when DOS XE is booted.
    - RAM memory locations 1802 ($70A or DRVBYT, the active drive map) and 1801
    ($709 or SABYTE, the maximum number of concurrently open files) are
    utilized in the same way as by DOS 2.0S and DOS 2.5.
    - DOS XE Master Diskette (DX5090) contains:
    DOSXE.SYS FMS with D: Disk File Manager, loaded by OS-resident
    Diskette Handler on system startup
    DOS2.SYS A: Disk File Manager for DOS 2.x filesystem support
    SETUP.COM External setup utility. Configures:
    - The number and type of drives
    - The number of file buffers
    - Installation of the 130XE RAMdisk
    - Whether the RS-232 handler should be loaded automatically
    on system startup
    - Whether a BASIC program should be run automatically
    on system startup
    RDRIVER.SYS Used by DOS XE to load R: handler from 850 interface
    COPY3_XE.COM DOS 3 to DOS XE copy program
    WELCOME.BAS Sample program provided for experimentation with SETUP.COM
    - Manual: Atari DOS XE: XF551 Disk Drive Owner's Manual C300557

    DOS XLE
    -------
    DOS II Version XLE ("DOS XLE") (P) 1990 Atari (Germany)
    Andreas Koch writes (January 2010):
    "programmed by Reitershan in 1990 (as requested by Atari Deutschland then
    for the XF551 drive), it is not only similar, but fully compatible to
    Turbo-DOS XL/XE (also by Reitershan). It uses the well-familiar DOS 2.5
    DUP-menu, with a few enhancements, like e.g. 1-8 for Dir. of drive 1-8,
    formats 90KiB-360KiB and RAMdisks up to 256KiB; there is even an option (P)
    to switch back to standard DOS 2.5; this DOS has been written with the
    source-code of DOS 2.5 (made available for Reitershan by Atari
    Deutschland), so it is as compatible as possible to DOS 2.5 but still
    offers some enhancements; luckily all Turbo-DOS XL/XE utilities can be used
    with this DOS (e.g. the RAMdisk-driver from Turbo-DOS!);

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

    Subject: 7.3.2) What are RealDOS, SpartaDOS X, and XDOS?

    The continuing development of various modern mass storage options for the
    8-bit Atari computers has necessitated ongoing development of supporting
    disk operating systems. This section describes full-featured disk operating systems (DOS) for the Atari that remain actively developed today.

    RealDOS
    =======
    RealDOS v1.0a Build 0031 (November 2012)
    - Shareware from Integrated Logic Systems (ILS, Stephen J. Carden)
    - Disk utilization/filesystem: SpartaDOS File System (SDFS) version 2.0
    - XL/XE with 64KiB RAM required. Also designed to run on APE software and
    hardware, or with an emulator.
    - RealDOS contains both the MUX- and non-MUX SIOV.
    This DOS will realize how it is being called and will load the proper SIOV
    handler for your needs. RealDOS will configure itself by detecting your
    hardware configuration.
    - Fully supports: Black Box (all versions), ICD MIO, Ken Jones MIO, KPI
    interface, Supra Interface, IDEa, SIO2PC, APE Registered Version, SIO2SD,
    SIO2IDE, SIO2USB, S-Drive and The Multiplexer.
    - RealDOS was also designed to work with the Atari800Win emulator.
    - RealDOS does not support at this time the cartridge version of the MyIDE
    product.
    Old version/Release history:
    RealDOS (or Real.DOS) shares its development heritage with disk-based
    SpartaDOS version 3.2c from ICD (which is described elsewhere in this FAQ
    list). The features and capabilities of RealDOS may thus be further
    described in terms of changes and improvements made since ICD SpartaDOS
    3.2c...
    (NOTE: Prior to Real.Dos Build 0026, distribution of RealDOS was private.
    Exception: the Video 61 SpartaDOS 3.3C cartridge described below.)
    -- SpartaDOS Ver 3.2p "30-Jan-86 Copyright (C) 1986 by ICD, Inc."
    o Support for the CSS Multiplexer ("MUX") in the form of a MUX-specific
    SIOV
    o Being based on SpartaDOS 3.2c, does not have the open file/directory
    bug/error found in later official SpartaDOS versions (3.2d, 3.2f, 3.2g,
    3.2gx), a problem known to be capable of trashing a hard drive
    o What was privately distributed as SpartaDOS 3.2p was initially
    developed from SpartaDOS 3.2c source code that was privately shared by
    ICD. During the development process all new/modified sources were
    lost, so new sources were then reverse-engineered (by Ken Ames for
    Steve Carden) from surviving working executables and from memory,
    leading finally to SpartaDOS 3.2p.
    o Date of distribution unknown -- unreflected in the Version info

    [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]

    newly debugged Atari BASIC Rev. B built-in on ROM. Unfortunately, while most existing bugs were fixed, Rev. B introduced a new bug more serious than any of the earlier problems. In his article in the June 1985 issue of Compute!, Bill Wilkinson writes:
    Each time you LOAD (or CLOAD or RUN "filename") a program, rev B adds 16
    bytes to the size of your program. If you then save the program, the next
    time you load it in it grows by ANOTHER 16 bytes, and so on.
    http://www.atarimagazines.com/compute/issue61/323_1_INSIGHT_Atari.php
    The problem can be alleviated by periodically, if not exclusively, using
    LIST instead of SAVE or CSAVE to save your programs.

    Atari never produced Atari BASIC Rev. B on cartridge.

    "Revision C Converter: Type-in fix for buggy BASIC revision B" by Matthew Ratcliff was published in the September 1985 issue of Antic: http://www.atarimagazines.com/v4n5/revisioncconverter.html

    Revision C
    ----------
    Atari BASIC Rev. C is the final "fully debugged" version. It was first made available on cartridge from Atari Customer Service in June 1984 (free to 600XL/800XL owners still within warranty). The silver label on the first Rev. C cartridges reads "(c)1982 Atari, Inc." and "Made in U.S.A." Atari, Corp. also produced Rev. C on cartridge, using two different silver labels designs, both of which read "(c)1985 Atari Corp." and "Made in Taiwan". Rev. C was
    also built-in on ROM in late-production 800XL computers as well as the 65XE, the 130XE, the XE System Console, and the 800XE.

    Determining Revision version
    ----------------------------
    When running Atari BASIC, memory location 43234 ($A8E2, BASIC ROM) indicates which Revision of BASIC is running. At the READY prompt, enter:
    ? PEEK(43234)

    If the result is: You have Revision: Atari Part#:
    162 A C012402+C014502
    96 B C060302A
    234 C C024947A

    All 3 versions of Atari BASIC may be available for download here: http://www.ataripreservation.org/websites/freddy.offenga/atari_dev.htm

    Manuals from Atari:
    (See the "What is the Atari OS" FAQ section for FPP documentation.)
    - Atari BASIC (Wiley Self-Teaching Guide) C014385 by Albrecht/Finkel/Brown
    (c)1979, 332 pages (see: http://www.atariarchives.org/basic/)
    - Shipped with the 400 computer systems from 1979-1981
    - Shipped with the 800 computer systems from 1979-1982
    - BASIC Reference Manual (400/800 ed.), C015307, (c)1980, 120 pages
    - Authors: Carol Shaw and Keith Brewster
    - Shipped with the 800 computer systems from 1980-1982
    - Inside Atari BASIC, C060992, Carris for Reston, (c)1983, 183 pages
    - Atari BASIC Reference Manual Update, C061038, (c)1982, 6 pages
    - BASIC Reference Manual (400/800/1200XL ed.), C061456 / BX4211, (c)1983,
    126 pages
    - Atari BASIC Reference Guide For Experience Programmers, C061570, (c)1983,
    14 pages
    - Atari BASIC Reference Guide, C061948, (c)1983 (international; 61 pages)

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

    Subject: 7.2.2) How do I load/run or save an Atari BASIC program on cassette?

    To load and run an Atari BASIC program from cassette:
    1. Insert the cassette into the recorder.
    2. Use REWIND or ADVANCE/F.FWD on the recorder, if necessary, to bring the
    tape to the position where the program is located.
    3. Boot the computer to the Atari BASIC READY prompt.
    4. There are several possibilities for the next step, depending on how the
    program was saved, and whether you want to run the program or just load
    it into RAM. Enter one of the following four commands:
    a. CLOAD loads programs saved with CSAVE
    b. LOAD "C:" loads programs saved with SAVE "C:"
    c. ENTER "C:" loads programs saved with LIST "C:"
    d. RUN "C:" loads and runs programs saved with SAVE "C:" 5. The system buzzer sounds (to signal you to press PLAY on the recorder).
    6. Press PLAY on the recorder.
    7. Press the RETURN key on the computer keyboard.
    Tape motion starts, the program loads from the cassette into RAM, and then
    tape motion stops.
    Then, if you entered RUN "C:" above, the loaded program runs; otherwise a
    READY prompt is displayed.
    8. You may press STOP on the recorder once the program is loaded, unless the
    program is designed to control further tape motion start/stop.
    9. If the loaded program is not running yet (you did not enter RUN "C:"
    above), now enter the command: RUN

    To save an Atari BASIC program from computer RAM to cassette:
    1. Insert a cassette into the recorder.
    2. Use REWIND or ADVANCE/F.FWD on the recorder, if necessary, to bring the
    tape to the position where the program is to be recorded.
    3. Enter one of the following three commands:
    a. CSAVE
    (short inter-record gap - fastest read/write speed - tokenized files)
    b. SAVE "C:"
    (long inter-record gap - middle read/write speed - tokenized files)
    c. LIST "C:"
    (long inter-record gap - slowest read/write speeds - straight ATASCII -
    tape actually stops in between block reads/writes)
    4. The system buzzer sounds twice (to signal you to press both PLAY and
    RECORD on the recorder).
    5. Press both PLAY and RECORD on the recorder.
    6. Press the RETURN key on the computer keyboard.
    Tape motion starts, the program is copied from RAM to the cassette, and
    then tape motion stops.
    7. You may press STOP on the recorder once recording has finished.

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

    Subject: 7.3.1) What is Atari DOS, and what versions did Atari release?

    This FAQ section describes the various DOS versions produced by Atari for use with their 8-bit computers: DOS I, DOS 2.0S, DOS 3, DOS 2.5, DOS XE, DOS XLE

    On the Atari, a complete Disk Operating System (DOS) consists of a complex, flexible combination of software components provided in the Atari OS on ROM with software components loaded into RAM from disk:

    1) SIO (Serial I/O bus Utility) routine
    - Component of the Atari OS
    - Generalized low level communications with SIO bus devices, including
    disk drives
    - Utilized by the Resident Diskette Handler
    - Normally utilized by the FMS
    2) Resident Diskette Handler
    - Component of the Atari OS
    - Utilizes SIO for communications with disk drives
    - Supports just five functions (four on the 400/800):
    1. GET SECTOR
    - Read a specified sector
    2. PUT SECTOR WITH VERIFY
    - Write sector; check sector to see if written
    3. STATUS REQUEST
    - Ask the disk controller for its status
    4. FORMAT
    - Issue a format command to the disk controller
    5. PUT SECTOR WITHOUT VERIFY
    - Write sector (don't check sector to see if written)
    - Available on XL/XE; not available on 400/800
    - 400/800: Uses 128 byte sectors
    XL/XE: Can read/write disk sectors having variable length from 1 to
    65536 bytes. Default=128 bytes
    - Normally only used to load the FMS from disk. Exception: Atari DOS I
    uses the OS-resident Diskette Handler for all disk communications.
    3) FMS (File Management Subsystem)
    - Must be loaded from disk (using the Resident Diskette Handler)
    - Normally utilizes SIO for disk drive communications
    - Does not utilize the Resident Diskette Handler. Exception: Atari
    DOS I uses the OS-resident Diskette Handler for all disk
    communications.
    - Normally provides a D: Disk File Manager device handler that is
    compatible with CIO
    4) CIO (Central Input/Output Utility) routine
    - Component of the Atari OS
    - Generalized high level, device independent access to device handlers,
    including any disk drive device handler provided by a FMS
    5) DUP (Disk Utility Package) or equivalent software program(s)
    - Optionally provided with a FMS
    - Must be loaded from disk using the FMS
    - Typically a DOS menu program, but could take any form of software
    that provides a user interface to FMS management functions
    - Normally utilizes CIO for carrying out disk management operations

    In practice, those DOS components loaded into memory from disk, that is, a FMS and any additional programs distributed with that FMS (such as a DUP), are normally collectively described as a "DOS" on the Atari.

    DOS I
    -----
    DISK OPERATING SYSTEM 9/24/79 COPYRIGHT 1979 ATARI
    - Contains two main parts:
    - A File Management Subsystem (FMS)
    - Developed by Paul Laughton (also wrote: Atari BASIC) for Shepardson
    Microsystems, Inc. (SMI) for Atari
    - A Disk Utility Package (DUP)
    - Shipped with 810 disk drives manufactured from 1980-1981.
    - Disk Utility Package (DOS menu) is loaded into memory with the FMS
    - Uses the OS-resident Diskette Handler for all disk communications via SIO
    - Disk drive type supported: Atari 810 (& compatible)
    - Disk utilization/filesystem: "DOS I"
    - 128 total bytes/sector, with 3 bytes of each sector used to address
    the next sector
    - 40 tracks * 18 sectors/track = 720 total sectors, with 11 sectors used
    for software control or unused by the FMS.
    - Data capacity per diskette:
    709 sectors x 125 bytes/sector = 88,625 bytes/disk
    - Cannot read disks written with DOS II, which require a 3 sector boot
    - 11 special sectors:
    1 Boot sector, containing the boot record accessed by the Atari OS
    at system power-up
    360 Volume Table of Contents (VTOC) (sector usage)
    361-368 File Directory (8 directory entries per sector)
    720 unused by the FMS (FMS interprets the VTOC sector bit map as
    sectors numbered 0-719, ignoring nonexistent sector 0, while the
    Atari 810 drive uses sectors numbered 1-720)
    - Maximum of 64 files per diskette (8-sector File Directory)
    - Uses binary file format unsupported by any other DOS version for the Atari
    - D: Disk File Manager supports up to four 810 disk drives, D1: through D4:
    - To configure DOS I for fewer drives (freeing system environment RAM),
    adjust memory location 1802 ($70A or DRVBYT):
    1. Boot the system to the BASIC READY prompt
    2. Enter one of:
    - POKE 1802,1 (for a one drive system; saves 397 bytes)
    - POKE 1802,3 (for a two drive system, saves 258 bytes)
    - POKE 1802,7 (for a three drive system, saves 130 bytes)
    - POKE 1802,15 (for a four drive system; DOS I default value)
    3. Go to DOS and use menu item H (WRITE DOS FILE) to write the DOS.SYS
    file (with the new value of location 1802) to disk, replacing any
    existing copy of DOS on that disk.
    - Can open up to 3 files simultaneously
    - Configurable by adjusting memory location 1801 ($709 or SABYTE) via
    the same process as described for adjusting the number of disk drives.
    Valid values for DOS I are 1-3 inclusive. Default is 3.
    - AUTO.SYS can be used to automatically poke data in RAM locations on
    system startup.
    - Files copied or duplicated in small buffer
    - Must redisplay menu before issuing new command
    - Can only write DOS system file to drive 1
    - N. DEFINE DEVICE menu option: "The full implementation of this selection is
    not supported, so use it with caution." --DOS Reference Manual p.39
    - DOS I is not compatible with the 850 Interface Module R: device handler
    - Disk File Manager Master Copy (CX8101) disk contains:
    DOS.SYS both the FMS with D: Disk File Manager and DUP with DOS Menu,
    loaded by OS-resident Diskette Handler on system startup
    - Manual: Disk Operating System Reference Manual C015200

    DOS 2.0S
    --------
    DISK OPERATING SYSTEM II VERSION 2.0S COPYRIGHT 1980 ATARI
    - Shipped with 810 and 1050 disk drives manufactured from 1981-1983.
    Master Diskette also shipped with the Atari Touch Tablet.
    - FMS (DOS.SYS) component developed by Paul Laughton for Shepardson
    Microsystems, Inc. (SMI) for Atari, based on the Atari DOS I FMS.
    Released code version: "19-Aug-80"
    - Disk Utility Package (DUP.SYS -- DOS menu) is separate from the FMS, and
    optional for use of the FMS, freeing up memory for user programs when the
    DUP is not needed. Released code version: "ver 2.9 11/18/80"
    - Does not use the OS-resident Diskette Handler once the FMS is loaded.
    - Utilizes SIO for disk drive communications
    - MEM.SAV file can be employed to preserve the contents of memory to disk
    when DUP.SYS is loaded.
    - Introduces support for AUTORUN.SYS binary file launch upon system boot
    (replaces AUTO.SYS of DOS I)
    - Disk drive type supported: Atari 810 (& compatible)
    - Disk utilization/filesystem: "DOS 2.0 Single Density"
    - 128 total bytes/sector, with 3 bytes of each sector used to address
    the next sector
    - 40 tracks * 18 sectors/track = 720 total sectors, with 13 sectors used
    for software control or unused by the FMS.
    - Data capacity per diskette:
    707 sectors x 125 bytes/sector = 88,375 bytes/disk
    - Requires a 3 sector boot (provision for double density version DOS 2.0D)
    - 13 special sectors:
    1-3 Boot sectors, containing the boot record accessed by the Atari
    OS at system power-up
    360 Volume Table of Contents (sector usage)
    361-368 File Directory (8 directory entries per sector)
    720 unused by the FMS (same as DOS I)
    - Maximum of 64 files per diskette (8-sector File Directory)
    - Difference in boot record lengths means DOS I and DOS II disks cannot be
    interchanged.
    - Established standard binary file format supported by ALL other DOS versions
    for the Atari (exception: Atari DOS I)
    - By default, the CIO-compatible D: Disk File Manager supports up to two 810
    disk drives, D1: and D2:
    - To configure DOS 2.0S for the number of 810 disk drives attached to the
    system (which affects system environment RAM), adjust memory location
    1802 ($70A or DRVBYT):
    1. Boot the system to the BASIC READY prompt
    2. Enter one of:
    - POKE 1802,1 (D1:)
    - POKE 1802,3 (D1: and D2: -- DOS 2.0S default value)
    - POKE 1802,7 (D1:, D2:, D3:)
    - POKE 1802,15 (D1:, D2:, D3:, D4:)
    - POKE 1802,31 (D1:, D2:, D3:, D4:, D5:)
    - POKE 1802,63 (D1:, D2:, D3:, D4:, D5:, D6:)
    - POKE 1802,127 (D1:, D2:, D3:, D4:, D5:, D6:, D7:)
    - POKE 1802,255 (D1:, D2:, D3:, D4:, D5:, D6:, D7:, D8:)
    3. Go to DOS and use menu item H (WRITE DOS FILES) to write the DOS
    system files (with the new value of location 1802) to disk,
    replacing any existing copy of DOS on that disk.
    - By default, can open up to 3 files simultaneously
    - Configurable by adjusting memory location 1801 ($709 or SABYTE) via
    the same process as described for adjusting the number of disk drives.
    Valid values for DOS 2.0S are 1-7 inclusive. Default is 3.
    - Files copied or duplicated into buffer which can be as large as user memory
    area
    - SAVE BINARY FILE has "/A" option allowing two files to be appended together
    - Can create load-and-go type file which enables you to select a file and
    have it automatically run without entering a RUN address
    - Diskette with bad sectors detected cannot be formatted
    - Screen margins are reset when DUP is entered
    - DUP: May enter another command or redisplay menu after a command
    - Can write DOS files to any drive
    - NOTE/POINT are available for random file access
    - Atari 810 Master Diskette II or Atari 810/1050 Master Diskette II (CX8104)
    disk contains:
    DOS.SYS FMS with D: Disk File Manager, loaded by OS-resident
    Diskette Handler on system startup
    DUP.SYS Disk Utility Package (DOS menu)
    AUTORUN.SYS Loads the R: device handler from an 850 Interface Module
    - Shipped with one Atari CX8111 Formatted Diskette II
    - Manuals:
    - Disk Operating System II Reference Manual C016347
    - Disk Utilities Listing, February 1981 C016558 (without binder)
    (DUP.SYS source code, early release)
    - DOS Utilities Source Listing (DOS II), August 1981 C017894
    ("Disk Utility Programs (DUP) ver 2.9 11/18/80")
    - Atari 810 Disk Drive: An Introduction to the Disk Operating System
    C060054 (CO60054)
    - Atari 1050 Disk Drive: An Introduction to the Disk Operating System
    C061529
    - On February 25, 1981, the source code to the Atari DOS 2.0S FMS (DOS.SYS)
    was purchased from SMI by Optimized Systems Software (OSS), headed by
    former SMI employees Bill Wilkinson and Mike Peters.
    - Inside Atari DOS (Compute! Books, 1982, 0-942386-02-7), authored by
    Bill Wilkinson, made the source code to the Atari DOS 2.0S FMS (DOS.SYS)
    available to the public. See: http://www.atariarchives.org/iad/
    - Modified versions of DOS 2.0S were widely created and exchanged among Atari
    users. Also notably, the first 3rd-party disk drives for the Atari, the
    Percom RFD-40S1 and RFD-44S1, were initially (1982) distributed with a
    program ("BLD") to build Percom DOS 2.0P (double density support) from a
    copy of DOS 2.0S.

    DOS 3
    -----
    Atari DOS 3 Copyright 1983
    - Shipped with 1050 disk drives manufactured from 1984 through early 1985.
    - Developed by 3-person team at Atari, led by Richard K. (Hud) Nordin
    - Project started at Atari by early 1981 under systems software manager
    Brian Johnston. Contributor: NEOTERIC consultant Harry B. Stewart
    - Disk drive types supported:
    1) Atari 810 (& compatible)
    2) Atari 1050 (& compatible)
    3) Atari 1450XLD built-in (1983 version: DS/ED 260KiB drive)
    Minimal support only: A single 1450XLD disk drive appears to DOS 3 as
    two Atari 1050 drives. That is, side 1 is accessed as D1: and side 2
    is accessed as D2:.
    - Disk utilization/filesystems:
    1) "DOS 3 Single Density"
    - Sector = 128 bytes
    - Block = 8 sectors = 1024 bytes
    - Track = 18 sectors = 2304 bytes
    - Disk contains 40 tracks, or 720 sectors, or 90 blocks, with 3 blocks
    used for software control.
    - Data capacity per diskette:
    87 blocks x 1024 bytes/block = 89,088 bytes/disk
    - Blocks 1-3 are used by the system as 24 special sectors:
    1-9 Boot sectors, containing the boot record accessed by the
    Atari OS at system power-up
    10-15 unused
    16-23 File Directory
    24 File Allocation Table (block usage)
    - Maximum of 63 files per diskette (8-sector File Directory)
    2) "DOS 3 Double Density" (enhanced/dual density)
    - Sector = 128 bytes
    - Block = 8 sectors = 1024 bytes
    - Track = 26 sectors = 3328 bytes
    - Disk contains 40 tracks, or 1040 sectors, or 130 blocks, with 3
    blocks used for software control.
    - Data capacity per diskette:
    127 blocks x 1024 bytes/block = 130,048 bytes/disk
    - Blocks 1-3 are used by the system as 24 special sectors:
    1-9 Boot sectors, containing the boot record accessed by the
    Atari OS at system power-up
    10-15 unused
    16-23 File Directory
    24 File Allocation Table (block usage)
    - Backward compatible with DOS 3 Single Density
    - Maximum of 63 files per diskette (8-sector File Directory)
    - Keyboard Command Processor (KCP) is separate from the FMS, and optional for
    use of the FMS, freeing up memory for user programs when the KCP DOS
    subfunctions and the DOS menu are not needed.
    - KCP Overlay (DOS menu) is separate from the FMS and KCP, and optional for
    use of the FMS and KCP, freeing up memory for user programs when the DOS
    menu is not needed.
    - MEM.SAV file can be employed to preserve the contents of memory to disk
    when the KCP Overlay (DOS menu) is loaded.
    - Supports AUTORUN.SYS binary file launch upon system boot
    - File manager and buffers now take up less space than the DOS 2 equivalents.
    All utilities, such as COPY, INIT, DUPLICATE (all UTL files) are called
    into memory only as needed. Each is maintained in a separate file.
    - Provides a direct method for the user to modify the FMS parameters
    - Provides an online HELP feature
    - Compared to DOS 2: The NOTE and POINT commands return a pointer number
    relative to the start of a file (byte 0) rather than an absolute sector and
    byte location within the sector.
    - Master Diskette 3 (DX5052) contains:
    FMS.SYS FMS with D: Disk File Manager, loaded by OS-resident
    Diskette Handler on system startup. Contains subfunctions:
    ERASE FILE, RENAME FILE, PROTECT FILE, UNPROTECT FILE, LOAD
    KCP.SYS Keyboard Command Processor, loaded on system startup if a
    cartridge is present. Contains subfunctions: SAVE,
    GO AT HEX ADDRESS, TO CARTRIDGE, COPY FILE, INIT DISK,
    DUPLICATE DISK, ACCESS DOS 2
    KCPOVER.SYS KCP Overlay, displays the DOS menu and process commands
    COPY.UTL COPY/APPEND utility
    DUPDISK.UTL DUPLICATE utility
    INIT.UTL INIT Disk utility
    CONVERT.UTL ACCESS DOS 2 utility, use to copy files from a DOS 2.0S disk
    to a DOS 3 disk
    HELP.UTL HELP utility
    HELP.TXT Text information displayed by the HELP utility
    HANDLERS.SYS Loads the R: handler from an Atari 850 Interface Module
    during system boot up, if this file is on the drive 1
    diskette.
    - Manuals for DOS 3:
    - Atari Disk Operating System Reference Manual C062287 (100 pages)
    (makes no mention of the 1450XLD built-in disk drive)
    - An Introduction to the Atari Disk Operating System C062288 (29 p)
    (makes extensive mention of the 1450XLD built-in disk drive)
    - Atari DOS 3 Reference Manual Errata, 05/01/84
    "Early versions of DOS 3 used a random access method that was incompatible
    with large files. To determine if you have an early version, boot your
    copy of DOS 3 with Atari BASIC, and execute the following BASIC command:
    PRINT PEEK(1816)
    If the value returned is '53', your copy of DOS 3 is the latest released.
    If the value returned is '51' or '56', Atari Customer Relations offered a
    program to update DOS 3 to the latest revision level."
    - Atari 1050 Disk Drive: An Introduction to the Atari Disk Operating
    System C024323 (international; 144 pages)

    DOS 2.5
    -------
    DISK OPERATING SYSTEM II VERSION 2.5 COPYRIGHT 1984 ATARI CORP.
    - Shipped with 1050 disk drives manufactured in fall 1985, and with XF551
    disk drives manufactured in 1987-1988.
    - Developed by Optimized Systems Software (OSS - Bill Wilkinson) for Atari
    - Disk drive types supported:
    1) Atari 810 (& compatible)
    2) Atari 1050 (& compatible)
    3) Atari 130XE RAMdisk (65,408 bytes)
    - Disk utilization/filesystems supported (detected automatically):
    1) DOS 2.0 Single Density
    2) "DOS 2.5 Enhanced Density" (or just "DOS 2.5")
    - 128 total bytes/sector, with 3 bytes of each sector used to address
    the next sector
    - 40 tracks * 26 sectors/track = 1040 total sectors, with 30 sectors
    used for software control or unused by the FMS.
    - Data capacity per diskette:
    1010 sectors x 125 bytes/sector = 126,250 bytes/disk
    - 30 special sectors:
    1-3 Boot sectors, containing the boot record accessed by the
    Atari OS at system power-up
    360 Volume Table of Contents (sectors 1-719 usage)
    361-368 File Directory (8 directory entries per sector)
    720 unused by the FMS (same as DOS I and DOS 2.0S)
    1024 Extended Volume Table of Contents (sectors 720-1023 usage)
    1025-1040 unused by the FMS (FMS uses a 10-bit sector address)
    - Maximum of 64 files per diskette (8-sector File Directory)
    - Backward compatible with DOS 2.0 Single Density
    3) "DOS 2.5 130XE RAMdisk"
    - 128 total bytes/sector, with 3 bytes of each sector used to address
    the next sector
    - 508 total sectors, with 9 sectors used for software control.
    - Data capacity:
    499 sectors x 125 bytes/sector = 62,375 bytes
    - 9 special sectors:
    360 Volume Table of Contents (sector usage)
    361-368 File Directory
    - Maximum of 64 files (8-sector File Directory)
    - Backward compatible with DOS 2.0 Single Density
    - RAM memory locations 1802 ($70A or DRVBYT, the active drive map) and 1801
    ($709 or SABYTE, the maximum number of concurrently open files) are
    utilized in the same way as by DOS 2.0S.
    - If the DOS 2.5 130XE RAMdisk is enabled, the default value for SABYTE is
    131, enabling D1:, D2:, and D8:, where D8: is the RAMdisk.
    - DOS 2.5 (DX5075) disk contains:
    DOS.SYS FMS with D: Disk File Manager, loaded by OS-resident
    Diskette Handler on system startup
    DUP.SYS Disk Utility Package (DOS menu)
    RAMDISK.COM If present on startup disk on an XL/XE with 128KiB RAM or
    more:
    1) Displays a message that it is initializing the RAMdisk
    2) Sets up a 64KiB RAMdisk as D8:
    3) Copies DUP.SYS to D8: and establishes MEM.SAV on D8:
    SETUP.COM External utility has 3 functional options:
    1) Change current drive number
    2) Change system configuration. 3 configurable options:
    i) Active drives number (1 to 4)
    ii) Max number of simultaneous files (1-7)
    iii) Disk writes with or without verify
    3) Create an AUTORUN.SYS that does either one or both of:
    - Load the R: handler from an Atari 850 Interface Module
    - Load and RUN a BASIC program from the boot disk
    COPY32.COM Utility to copy files from a DOS 3 disk to a DOS 2.5 or to a
    DOS 2.0S disk
    DISKFIX.COM DiskFix Utility can be used to:
    - Unerase a file (under certain circumstances)
    - Verify the soundness of every file on a disk
    - Rename a file by number (solves problem of files with
    duplicate names)
    - Manuals:
    - Atari DOS 2.5: 1050 Disk Drive Owner's Manual C072033
    - Atari DOS 2.5: XF551 Disk Drive Owner's Manual C033537

    DOS XE
    ------
    DOS XE DISK OPERATING SYSTEM COPYRIGHT 1988 ATARI CORP. VERSION 01.00
    - Shipped with late production XF551 disk drives starting in 1989
    - Developed by Bill Wilkinson for Atari. Known as "ADOS" prior to release
    - Requires an XL/XE; does not run on the 400/800
    - Disk Utility Package (DOS menu) is loaded into memory with the FMS
    - Disk drive types fully-supported (with internal provision for up to 8
    drive types):
    1) Atari 810 (& compatible)
    2) Atari 1050 (& compatible)
    3) Atari XF551 (supports XF551 high speed)
    4) Atari 130XE RAMdisk (64KiB)
    5) SSDD 5.25" Single-Sided, Double Density
    - Disk utilization/filesystems:
    1) "DOS XE" via the native D: Disk File Manager:
    - All disks are addressed in 256 byte (logical) sectors.
    - Simulates 256 byte sectors on 810 and 1050 disk drives, which
    have 128 byte physical sectors, by reading and writing physical
    sector pairs.
    - Five different types of sectors:
    1) Boot sectors
    - Disk sectors 1-3 contain the boot record accessed by the
    Atari OS at system power-up. (OS reads 128 bytes/sector)
    - Contains a 32 byte Drive Table describing the physical and
    logical layout of the disk.
    - The DOS XE 130XE RAMdisk does not have boot sectors.
    2) Volume Table of Contents (VTOC) sectors
    - Starts in sector 4 (one sector only for drive types supported
    by DOS XE).
    - The first 10 bytes give information about the current status
    of the disk and the rest is a bit map of the blocks on the
    disk.
    3) Directory sectors
    - The first directory block immediately follows the VTOC
    sector(s). Additional directory blocks are allocated as
    needed and may be scattered throughout the disk, linked by a
    two-byte pointer at the end of each block.
    - Each entry contains the file name, information about the
    file (including creation date and last modified date), and up
    to 12 two-byte pointers which point to the file map blocks
    for the file.
    - Includes a six byte sector label, containing the File ID
    number, Volume number, and Sequence number.
    4) File Map sectors
    - Contain from 1 to 125 two byte data block pointers.
    - Includes a six byte sector label, containing the File ID
    number, Volume number, and Sequence number.
    5) Data sectors
    - 250 bytes allocated for data.
    - Includes a six byte sector label, containing the File ID
    number, Volume number, and Sequence number.
    - Files can be up to 8MiB long.
    - There is a limit of 1250 files per directory/subdirectory, but no
    theoretical limit to the number of directories.
    - There is an 80 character limit on pathnames.
    - Up to 64KiB sectors can exist on a single disk.
    (65536 sectors x 256 bytes/sector = 16MiB)
    - Data capacity per disk for fully-supported drive types:
    - AT810: 347 usable sectors * 250 bytes/sector = 86,750 bytes
    - AT1050: 507 usable sectors * 250 bytes/sector = 126,750 bytes
    - XF551: 1435 usable sectors * 250 bytes/sector = 358,750 bytes
    - 130RAM: 251 usable sectors * 250 bytes/sector = 62,750 bytes
    - SSDD: 715 usable sectors * 250 bytes/sector = 178,750 bytes
    (Note that when DOS XE reports free disk space it truncates the
    number of bytes free to the nearest 1000 "K" bytes. For example, an
    empty AT810 disk is reported by DOS XE to have 86 K bytes free.)
    - Filesystem analysis by James Bradford (2009):
    https://atariage.com/forums/topic/154173-bored-so-i-did-this-part-2/
    2) DOS 2.0 Single Density via the optional DOS 2.x A: Disk File Manager
    3) DOS 2.5 Enhanced Density via the optional DOS 2.x A: Disk File Manager
    - Disk File Managers can address up to eight drives (D1: to D8:, A1 to A8:).
    - Hybrid interface is both menu driven and command driven, including stacked
    command entry.
    - Batch files can be used to automate tasks;
    AUTOEXEC.BAT run automatically when DOS XE is booted.
    - RAM memory locations 1802 ($70A or DRVBYT, the active drive map) and 1801
    ($709 or SABYTE, the maximum number of concurrently open files) are
    utilized in the same way as by DOS 2.0S and DOS 2.5.
    - DOS XE Master Diskette (DX5090) contains:
    DOSXE.SYS FMS with D: Disk File Manager, loaded by OS-resident
    Diskette Handler on system startup
    DOS2.SYS A: Disk File Manager for DOS 2.x filesystem support
    SETUP.COM External setup utility. Configures:
    - The number and type of drives
    - The number of file buffers
    - Installation of the 130XE RAMdisk
    - Whether the RS-232 handler should be loaded automatically
    on system startup
    - Whether a BASIC program should be run automatically
    on system startup
    RDRIVER.SYS Used by DOS XE to load R: handler from 850 interface
    COPY3_XE.COM DOS 3 to DOS XE copy program

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