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Atari 8-Bit Computers: Frequently Asked Questions
Section - 7.1) What versions of the Atari Operating System (OS) are there?

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Atari 8-bit Operating Systems

Version 3.6, 2009-05-05
By Freddy Offenga

400/800 10kB OS roms

Rev. TV    Date        CRC-32      Part Nr(s)
~~~~ ~~~~~ ~~~~~~~~~~~ ~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~
A    NTSC  1979        0xc1b3bb02  CO12499A, CO14599A, CO12399B
A    PAL   1979        0x72b3fed4  CO15199, CO15299, CO12399B
B    NTSC  1981        0x0e86d61d  CO12499B, CO14599B, 12399B
B    PAL   (*)         (*)         (*)

(*) a real PAL.B rom hasn't been found.
If you do have this or have more information, please let me know!

XL/XE 16kB OS roms

Rev. System  Date        CRC-32      Part Nr(s)
~~~~ ~~~~~~  ~~~~~~~~~~~ ~~~~~~~~~~  ~~~~~~~~~~~~~~~~~~~
10   1200XL  10/26/1982  0xc5c11546  CO60616A, CO60617A
11   1200XL  12/23/1982  0x1a1d7b1b  CO60616B, CO60617B
1    600XL   03/11/1983  0x643bcc98  CO62024
2    XL/XE   05/10/1983  0x1f9cd270  CO61598B
3    800XE   03/01/1985  0x29f133f7  C300717
3B   65XE    07/21/1984  0x45f47988  C101700
4    XEGS    05/07/1987  0x1eaf4002  C101687

The 400/800 O.S's consist of three ROMs (two 4kB and one 2kB).
The 1200XL contains two ROMs for the OS (8k each), XL/XE's use a single
16k ROM and the 16k XEGS OS is stored in a 32k ROM (together with 8k
BASIC and 8k for Missile Command).

Origins of ROM information
400/800 rev.A NTSC      
All information from OS board C012989 (Rev D) and ROM dumps.

400/800 rev.A PAL
All info found in two Atari 400's and Atari 800 ROM module CX801.P

400/800 rev.B NTSC
Information from a ROM dump and the rev.B source listing.
The part numbers were listed in the catalog from [BEST]. 
According to [MAPPING] rev.B ROMs have a 'B' at the end of the part number, 
therefore I figure these part numbers are from rev.B.

400/800 rev.B PAL
Could exist, since the NTSC version exists and there's some conditional
PAL/NTSC assembly in the rev.B source code.

1200XL rev.10
All info found in an Atari 1200XL (both US and Taiwan).
[REV2] refers to it as rev.10. [BEST] calls it rev.A.

1200XL rev.11
Information from ROM dump. Needs confirmation.
[REV2] refers to it as rev.11. [BEST] calls it rev.B.

600XL rev.1
All info found in an Atari 600XL.

XL/XE rev.2
All info from Atari 800XL machines (PAL, NTSC and SECAM).
This version is also used in 130XE and 65XE machines.

800XE rev.3
All info found in an 800XE machine.

65XE (Arabic) rev.3B
The OS rev.3B is a 16K rom dump from an 65XE Atari from Arabia.
It's probably based on rev.3. There are changes in the fonts
(Arab characters) and several patches in the code [ARABIC2].

XL/XE rev.4
All info found in an Atari XE Game System (confirmed).

O.S. Authors and dates
The following info is from the Atari XL/XE rev.2 source code [REV2].

Revision A (400/800)
D.Crane / A.Miller / L.Kaplan / R.Whitehead

Revision B (400/800)
Fix several problems.
M.Mahar / R.S.Scheiman

Revision 10 (1200XL)
Support 1200XL, add new features.
H.Stewart / L.Winner / R.S.Scheiman /
Y.M.Chen / M.W.Colburn                          10/26/82

Revision 11 (1200XL)
Fix several problems.
R.S.Scheiman                                    12/23/82

Revision 1 (600XL/800XL)
Support PBI and on-board BASIC.
R.S.Scheiman / R.K.Nordin / Y.M.Chen            03/11/83

Revision 2 (600XL/800XL)
Fix several problems.
R.S.Scheiman                                    05/10/83
Bring closer to coding standard (object unchanged)
R.K.Nordin                                      11/01/83

The following OS roms originate from rare Atari 8-bit systems.
Since I don't own any of these (unfortunately), I don't have much
information about these roms. Who can help me?

I've got two 16K rom dumps from the 1450XLD. Both ID's are rev.3.
The first dated 3/23/1984 comes from the 'Pooldisk Too' CD-ROM [POOL2]
(filename: 1540os3.v0) and the second dated 6/21/1984 was send to
me by Nir Dary (filename: os1450.128). Main differences between
these two are in the first 3K ($C000 - $CBFF).

Rev. System   Date        CRC-32      Part Nr(s)
~~~~ ~~~~~~~  ~~~~~~~~~~  ~~~~~~~~~~~ ~~~~~~~~~~
3    1450XLD  3/23/1984   0x0d477aa1  ? 
3    1450XLD  6/21/1984   0xd425a9cf  ?

[ARABIC] Arabic 65XE,

[ARABIC2] Arabic 65XE (2),

[BEST] Best Electronics, catalog of Atari 8-bit parts.

[MAPPING] Mapping the Atari, revised edition, Ian Chadwick, Compute! books
publication, 1985.

[POOL2] Atari Pooldisk Too,

[REVB] The modified september Atari 400/800 computer operating system
listing, revision B, (c)1982 Atari.

[REV2] The Atari O.S. source code rev.2, (c)1984 Atari.

[XLADD] Atari XL addendum Atari home computer system operating system
manual: supplement to Atari 400/800 technical reference notes.

Thanks to
- Laurent Delsarte for Arabic ROM dump and additional info.
- Michael Current for good info about Rev.11 and the Arabic roms.
- Nir Dary for the rev.2 source code, rom dumps and the 1200XL.
- Sijmen Schouten for his reconstructed 400/800 Rev.B source code.
- Stephen Sheppard for 400/800 Rev.A/NTSC information and rom dumps.
- Steve Tucker for the 1200XL OS ROM dumps.

(end of section content by Freddy Offenga)

Some additional info about the Rev. 3 XL/XE OS from ST*ZMAGAZINE #36, Sept. 1,
1989 (as reprinted in PSAN Nov 89):

by Mark Elliot, Innovative Concepts
The following changes have been incorporated in the 130XE computer.

The O.S. has minor changes like:
  A) The MEMORY TEST (from SELF TEST) tests the extra 64K now! (in 4 squares)
  B) Also, the MEMORY TEST checks the first 48K over TWICE as fast as before!
  C) The KEYBOARD TEST has the F1-F4 keys missing on top.  (function keys),
     although the code that interprets them is probably there (like XEGS).
  D) Also, it types out "COPYRIGHT 1985 ATARI" at the keyboard test, when all
     tests are done.  (compared to COPYRIGHT 1983 ATARI, before)
  E) And, the O.S. chip itself, is on a 27256 EPROM, but only half of it is
     used! (compared to the original, which was on a 16K x 8 ROM, 27128 comp.)

In Atari BASIC, PEEK(65528) and PEEK(65527) return the following unique values
depending upon the version of the Atari OS that is running:

  221 = 400/800 OS Rev. A NTSC
  214 = 400/800 OS Rev. A PAL
  243 = 400/800 OS Rev. B NTSC

   10 = XL/XE OS Rev 10
   11 = XL/XE OS Rev 11
    1 = XL/XE OS Rev 1
    2 = XL/XE OS Rev 2
    3 = XL/XE OS Rev 3
   59 = XL/XE OS Rev 3B (Arabic)
    4 = XL/XE OS Rev 4

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Top Document: Atari 8-Bit Computers: Frequently Asked Questions
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Next Document: 7.2) What other operating systems have been produced for the Atari?

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