8.4) What programs run only on the 400 and 800 models, and why?

Subject: 8.4) What programs run only on the 400 and 800 models, and why?

The following are reported as incompatible with models other than the
original Atari 400/800. Most probably do work on XL/XE's if you use a
translator to run the original 400/800 OS on your XL/XE.

Apple Panic Broderbund
Aquatron Sierra On-Line
Astro Chase (by First Star Software) Parker Bros.
Atari Word Processor Atari
(this is not the same as AtariWriter!)
Atlantis (some versions!) Imagic
Attack at EP-CYG-4 (by Bram) Romox
Bacterion! Kyle Peacock/Tom Hudson/ANALOG#20
( http://www.cyberroach.com/analog/an20/bacterion.htm
patch for XL/XE available:
http://www.cyberroach.com/analog/an20/bacterion_patch.htm )
Bandits Sirius Software
BearJam Chalkboard
Boulders And Bombs CBS
Chicken Synapse
Dancing Feats (by Softsync) Romox
Demon Attack Imagic
Dreadnaught Factor, The Activision
Drelbs Synapse
File Manager 800+ Synapse
Forbidden Forest Cosmi
(later versions by different companies work ok on XL/XE!)
Fort Apocalypse Synapse
(cart version is 400/800 only! tape+disk versions work ok on XL/XE!)
Galahad And The Holy Grail APX
(Downloadable: http://www.atariarchives.org/APX/showinfo.php?cat=20132)
Go Hayden
Gorf Roklan
Jawbreaker II Sierra On-Line
Jet Boot Jack English Software
(can be found on various tapes/disks; at least the re-release
version by Byte Back works alright on XL/XE computers!)
Juggler IDSI
K-Razy Antiks K-Byte
K-razy Kritters CBS
K-razy Kritters K-Byte
Kangaroo Atari prototype
KoalaPainter Koala
Leo's 'Lectric Paintbrush Chalkboard
Leo's Links Chalkboard
Letter Perfect (before v6) LJK
LogicMaster Chalkboard
Mac/65 [ver. 1.00, orange] OSS
Mario Bros. ('83) Atari
Maze Epyx
Micro Illustrator Chalkboard
MicroMaestro Chalkboard
Monkey Wrench Eastern House
Monster Maze Epyx
Ms. Pac-Man Atari
(has problems with newer XE/XEGS computers!)
M.U.L.E.(early release only) Electronic Arts
Nautilus Synapse
Pac-Man Jr. Atari prototype
Picnic Paranoia Synapse
Pool 1.5 IDSI
Pool 400 IDSI
Protector II Synapse
QS Forth James Abanese / [QS] Quality Software
Rack 'Em Up Rocklan
Shamus Synapse
Slime Synapse
Snapper Silicon Valley Systems
Space Dungeon Atari
Squish 'Em Sirius
Super Pac-Man Atari prototype
Synassembler Synapse
Text Wizard Datasoft
Zaxxon (early release only!) Datasoft

Konrad M.Kokoszkiewicz writes:

XL/XE software won't work on 400/800 if:

1) it uses shadow RAM at $C000-$CFFF and $D800-$FFFF
2) it uses RAM expansions at $4000-$7FFF controlled by PORTB $D301
3) it uses specific XL OS functions (like JNEWDEVC)
4) it uses illegal XL OS addresses.
5) it uses European Charset :)

Andreas Magenheimer adds:

To get an overview or see a chart of OS changes from the 800 to the XL
line, refer to Antic magazine Volume 3, Number 2 (June 1984), pages 10-14;
(online: http://www.atarimagazines.com/v3n2/insideatari.html )
Also note, that some software will not work correct (or not at all) on
newer XE/XEGS versions (which have a new OS with a new version number,
a new selftest/memory-test/keyboard-test, larger RAM chips, etc. etc.);

Thomas Richter contributes further details (16 Jan 2004):

There are a couple of reasons why some games don't run on the XL/XE
models. I try to order them by "likeliness", of course biased by my
personal observations:

i) The printer buffer of the XL Operating System in page 3 is a couple
of bytes shorter. The additional bytes are used for extended OS
variables not available in the 800 series. Most prominent is the $3fa
location, holding a shadow register of GTIA's TRIG3 signal. While a
true joystick trigger line in the 400/800 series, this signal is used
as "cart inserted" signal for XL/XE models. Unfortunately, the OS
compares GTIA trig3 with the shadow register at $3fa in each vertical
blank, running into an endless loop if the register contents don't
match. This causes hangs for games using page 3 either as copy-buffer
or for player-missile graphics. (Hangs by Ms. Pac-Man and
Bacterion! are caused by this, and many others...) This is "fixable"
either by the translator disk, or by a quick hack into the game,
replacing the OS vertical blank or poking TRIG3 frequently into its
shadow. The reason for the OS behaviour might be that Atari wanted to
prevent crashes if the cartridge is inserted or removed while the
machine is running. The 400/800 is powered down when a cart is
inserted, the XL/XE lacks the cover of the older models that triggered
a little switch to interrupt the power line.

ii) Similar to the above, writes to $3f8. This OS equate defines
whether on a warm start, the BASIC ROM shall be mapped back in. If
its contents are altered, a program triggering a reset as part of its
initialization will find itself then with 8K less RAM occupied by
a BASIC ROM, making it crash. Similarly, writes to the cartridge checksum
$3eb could cause a cold-start on a "reset initialization". This is
fixable by the translator disk.

iii) Some games use a four-joystick setup, or at least initialize
PIA itself. If this happens inadequately, PIA Port B, bit 0 gets changed,
disabling the ROM, and thus crashing the machine. This is not fixable
by the translator since it is a hardware issue.

iv) Direct jumps into the OS ROM, not using the documented vectors in
the $e450 area. Interestingly, this fault is not as common as it may
sound since games hardly ever use the OS. It causes failures of
some "serious applications", most notably "QS Forth" and applications
compiled by it. This is fixable by the translator disk.

As a side remark, it is interesting to note that no such documented
jump-ins exist for the math-pack ($d800 to $dfff). It is not really
part of the OS, but looks more like a part of the BASIC interpreter
that didn't make it into the OS because there was no room left. Thus,
direct jump-ins have to be used here that are documented in the De Re
Atari (for example). Atari never changed them, but it seems likely
that this documentation happened more or less as an accident since the
same source also lists some mathematics-related jump-ins into the
Basic (namely, to compute SIN and COS and related) that are only valid
for the Rev. A BASIC. Thus, the math pack might be a couple of
routines that have been originally intended for "private use" of the
BASIC ROM, but then have been found "too useful" by many others to
remain "closed". Otherwise, it is hard to explain why the otherwise
pretty cleaned-up OS comes with a construction like this.