[continued from previous message]

(filenaming convention used on CompuServe before February 1987)

Additional file extensions associated with Atari picture formats are listed at the website for RECOIL (Retro Computer Image Library), a viewer of pictures in native formats of the Atari 8-bit (and other platforms) for modern computers: http://recoil.sourceforge.net/

Additional file extensions associated with Atari music formats are listed at the website for ASAP (Another Slight Atari Player), a player of Atari 8-bit music for modern computers: http://asap.sourceforge.net/

File extensions associated with Atari disk image, cassette image, or cartridge ROM formats normally used with Atari emulators, rather than on the Atari itself, are described elsewhere in this FAQ list.

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

Subject: 7.3.6) What Atari programs can use MS-DOS 5.25" or 3.5" diskettes?

Except for recent versions of SpartaDOS X, Disk Operating Systems designed for the Atari are not designed to use MS-DOS format floppy disks directly, in part corresponding to the fact that disk drives designed for the Atari do not normally support such disk formats.

This section highlights software programs designed to run on the Atari that allow the Atari to use an MS-DOS formatted floppy disk in combination with a disk drive also supporting such formats.

Solutions involving modern storage devices with firmware that emulates Atari floppy disks, so that the devices can be used by Atari DOS versions using native Atari DOS filesystems, are described elsewhere in this FAQ list.

IBMXFR IBM Transfer Program, by Happy Computers, Inc.
- For use with the Happy 1050 Enhancement upgrade for the Atari 1050
- Can read/write 5.25" SS-DD MS-DOS format 180KiB floppy disks

IBM DOS and IBM 360, by TOMS
- Available on ROM in TOMS Turbo Drive LDW, TOMS Multi Drive LDW, and
TOMS Multi Drive 1050 disk drive upgrades
- Can read/write 5.25" SS-DD MS-DOS format 180KiB floppy disks

IBMST, by TOMS
- Available on ROM in TOMS 720/720C/720CR floppy disk drives for the Atari
- Can read/write:
- 5.25" SS-DD MS-DOS format 180KiB floppy disks
- 5.25" DS-DD MS-DOS format 360KiB floppy disks
- 5.25" DS-DD Atari ST (MS-DOS like) format 720KiB floppy disks

IBMREAD.COM IBM/ST Transfer Utility, by Computer Software Services (CSS)
- Supplied on disk with the XF Update, XF Single Drive Upgrade, and
XF Dual Drive Upgrade for the Atari XF551
- With XF Update, can read:
- 5.25" SS-DD MS-DOS format 180KiB floppy disks
- 5.25" DS-DD MS-DOS format 360KiB floppy disks
- With XF Single Drive Upgrade or XF Dual Drive Upgrade, can read:
- 3.5" SS-DD MS-DOS format 360KiB floppy disks
- 3.5" DS-DD MS-DOS format 720KiB floppy disks
- Supports the increased sector density of the 'twister' ST disk formats
(10 sectors/track)
- Supports ASCII->ATASCII text conversion

BBXFER.COM, version 1.9, by Computer Software Services (CSS)
- Available on ROM in CSS Black Box/Floppy Board interface combination
- Can read/write:
- 5.25" SS-DD MS-DOS format 180KiB floppy disks
- 5.25" DS-DD MS-DOS format 360KiB floppy disks
- 5.25" DS-HD MS-DOS format 1200KiB floppy disks
- 3.5" SS-DD MS-DOS format 360KiB floppy disks
- 3.5" DS-DD MS-DOS format 720KiB floppy disks
- 3.5" DS-HD MS-DOS format 1440KiB floppy disks

SpartaDOS X, by DLT Ltd.
- Can read MS-DOS FAT12 (as of SDX 4.46) or FAT16 (as of SDX 4.47)
format storage media, including floppy disks and hard disks
- Hardware device must support 512-byte sectors
- SDX detailed elsewhere in this FAQ list

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

Subject: 7.4) Are there Graphical User Interfaces (GUIs) for the Atari?

Section started by: Andreas Koch
Other contributors: Mathy van Nisselroy, Kathleen Ferrante

G.O.S. by Total Control Systems (David Sullivan)
- Public domain program released 1986 (written in Action!)

Window XL/XE (c)1986, by Joerg Forg / Megamania Soft inc.
- Andreas Koch writes: a Turbo-BASIC XL GUI with some nice add-ons, like
calculator, editor and other things.

RAOS (Rat Actuated Operating System) by Zobian Controls
- Marketed 1986/1987 for use with the company's SuperRAT or earlier RAT
mouse controllers (neither of which shipped)
- Was to include Z-DOS desktop (DUP.SYS replacement)
- Never shipped

XL-TOS by Marc Ebner
- Published in Atari Magazin, 1987/01 Jan/Feb, with supplements published
in issues 3/4-87 Mar/Apr and 5/6-87 May/Jun.
- Andreas Koch writes: the BASIC file, which consists of many data lines
creates a short object code file); unfortunately this GUI only looks
good, it loads almost nothing...

GOE (cartridge), developed by Total Control Systems (David Sullivan)
- Written in Assembly
- Promoted by Merrill Ward & Assoc. / Shelly Merrill as "ST Jr." early 1988
- Demo version(s?) released by TCS fall 1988
- Full cartridge version never shipped.

Diamond GOS, developed by Reeve Software / ReeveSoft (Alan Reeve)
(co-marketed by USA Media / Shelly Merrill as "ST Jr." Aug 1988 - Apr 1989)
- Supports: DOS 2.5 and compatible, SpartaDOS, DOS XE
o Diamond GOS version 1 (1988)
- Diamond DeskTop 1.0 (disk) DUP.SYS replacement
o Diamond GOS version 2 (1989) package:
- Diamond DeskTop 2.0 (cartridge) + Utility Diskette
- Diamond Programmer's Kit (Programmer's Manual)
- Diamond Paint (disk)
o Diamond GOS version 3 (1991) package:
- Diamond DeskTop 3.0 (cartridge) + utility diskette
- Diamond Paint (disk)
- Diamond Write (disk)

Atari Desktop, by Piotr Bieniek (c) 1992 ABC Software (Poland)
Andreas Koch writes: includes editors, converters, file copiers, sector
copy, tape+turbo tape copy, small games, CMC finder and player and much
much more; works with 64KiB RAM and keyboard input; disk manuals only in
Polish language...

Screen Aided Management (SAM) by RaindorfSoft for Power Per Post (Germany)
- It is available in two different versions:
a) Atari magazin type-in listings or Lazy Fingers disks (public domain)
b) Commercial version 2.0 which has many add-ons
- Supports: Atari DOS 2.5
- V1.25i, 1994 is available from DGS, http://www.dgs.clara.net/
DGS SAM page: http://www.dgs.clara.net/sam.htm

BOSS-XL by Mirko Sobe (MS Software)
- Requires 64KiB XL/XE
- Supports: ATARI-DOS, Turbo-DOS
- Current Version: v4.5 Edition 2000 (primary development 1993-1997)
- System Software:
- File Manager (Desktop was the BOSS-XL V2.0)
- BOSS-font editor (XE-version)
- Icon Editor (XL-/XE-Version)
- Written in Turbo-BASIC XL

BOSS-XE by Mirko Sobe (MS Software)
- Requires 64KiB XL/XE, 128KiB or more recommended
- Supports: ATARI-DOS, Turbo-DOS
- Current Version: v8.1 Edition 2000 (developed 1997-2000)
- Written in Turbo-BASIC XL
- System Software:
- BOSS parameter
- BOSS-font editor (XE-version)
- Icon editor (XL / XE version)

BOSS-X by Mirko Sobe (MS Software)
- Requires 128KiB XL/XE, 256KiB or more recommended
- Supports: MYDOS 4.50 and above; Atari ST Mouse
- Current Version: 10:33, 2003 (developed 2000-2003)
- Written in Turbo-BASIC XL
- System Software:
- File Manager
- BOSS parameter
- BOSS-font editor (X version)
- Icon editor (X version for colored symbols)
- BOSS-X framework
- multiple screen savers

ST-TOS a small BASIC program, that looks like a GUI; it can merely load
BASIC files and do a few DOS commands, like lock, unlock, delete and such...

BASIC desktop, a GUI written in BASIC just as a sample, what can be done
with an 8-bit computer; this one loads BASIC and text files (maybe also ML
files);

DCS, the desktop construction set from Tom Hunt; there are 3 different
versions available, a) for DOS 2.5, b) for MyDOS and c) for Sparta-DOS; I have tested the Sparta DOS version, which worked with batchfiles and could easily load some ML files, text files and BASIC files (which were already on the DCS disk); it also works with high densities and/or hard disk partitions up to 16MiB and supports subdirs of course; hmm, freeware or shareware ?!?

ATOS - GUI by Tom Hunt/Closer To Home.
1) Lets you use any demo or intro as a screen saver!!
2) Works with all Atari hardware, BB, MIO and Hard drives, SpartaDOS support
3) Lets you run files like full games and demos and then
return back to the desktop. It uses Overlays.

TRS Desktop by Tristesse (By Epi, Pin, Trub) (2005)
- A graphic user interface for SpartaDOS X to be used with hard drives.
- http://www.atari8.info/trsdesktop.php
- http://trub.atari8.info/sdx_files/TRS_desktop_v09d_alfa.zip

GUI project demo, by Jonathan Halliday (2012)
- A work in progress

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

Subject: 7.5) What should I know about R: and T: modem device handlers?

The Atari computer Operating System does not provide a modem device handler. Modems can be connected to the Atari in several different physical ways: via
an 850 interface or equivalent, via a joystick/controller port, or via the SIO port. For each way a modem can be connected to the Atari, application
software code specific to that type of modem must be utilized by the computer to communicate with the modem.

Some Atari programs, especially commercial telecommunications programs, simply support one or several specific modem types, incorporating the necessary modem-specific software routines internally.

Some programs, especially earlier public domain/freeware/shareware programs, were released in several versions, each dedicated to a particular modem or modem type.

Finally, as multiple modem types gained popularity, public domain/freeware/ shareware authors started abstracting the modem device handling software routine from the rest of their telecommunication programs, allowing for a single version of the main program to work with one or more separately- distributed modem handler routines. Users were then expected to combine an application with an appropriate modem handler in order to create a complete, working telecommunications software package.

This section attempts to list all Atari modem device handler files that can be used in combination with telecommunications programs requiring such a handler.

R: modem device handler on 850 interface ROM

The 850 contains an R: handler, supporting devices R1: through R4:, in its
ROM. This R: handler supports the full range of capabilities of the RS-232-C serial interface ports provided by the 850, but is typically used with an RS- 232-C serial interface modem.

With no powered disk drive #1 present, the R: handler loads from the ROM of a powered 850 into computer RAM on system startup. An extended beep is emitted through the computer's audio signal as the handler is loaded.

The R: handler can also be loaded from 850 ROM into computer RAM as part of a system Disk Boot or afterward by running a brief software utility for that purpose. Such utilities include:
- AUTORUN.SYS, distributed with Atari DOS 2.0S (1980)
- RS232.COM, distributed with OS/A+ and DOS XL by OSS (1982-1984)
- RS232FIX.COM, distributed with DOS XL by OSS (1982-1984).
Explicitly attempts to correct some of the known bugs in the 850 R: handler. - HANDLERS.SYS, distributed with Atari DOS 3 (1983)
- RS232.ARx, distributed with SmartDOS by Rana Systems (1984)
- Should be renamed RS232.AR1 to be autorun by SmartDOS
- Supports both warm and cold re-boots of the system
- AUTORUN.SYS, as generated by the Atari DOS 2.5 SETUP.COM utility (1984)
- RS232.COM for SpartaDOS, distributed with ICD SpartaDOS and with the ICD
P:R: Connection (1986)
- RS232.SYS for Atari DOS 2, distributed with the ICD P:R: Connection (1986)
- BOOT850.COM, distributed with AMODEM 7.4 and 7.5 by Trent Dudley (1987)
- RDRIVER.SYS, distributed with Atari DOS XE (1988)
- ATARI850.AUT, distributed with MYDOS 4.50
- X850.COM, distributed with ANSITERM by Robert Sinclair (1992)
- PR.COM, distributed with ANSITERM by Robert Sinclair (1992)
- RS232.COM, part of RealDOS
- RS232.COM, part of SpartaDOS X

Special to the P:R: Connection (popular 850 workalike):
- PRC.SYS is an R: handler "translator" distributed with the P:R: Connection
by ICD (1986). Allows some telecommunications programs (such as HomePak
HomeTerm) with integrated support for 850-based modems, but that do not load
or use the internal 850 R: handler, to work with the P:R: Connection.

R: modem device handlers for MPP-1000/1000C/1000E and Supra 300AT modems

- MPPHAND.AUT, Version 1.0, by John S. DeMar, 1983(?)
'Smartmodem and "R:" Device Emulator, for the MPP-1000C Modem'
- MPP 1000C Modem/850 Emulator by Jordan Chilcott. Three versions:
- MPP850.DRV -- MPP Modem Driver Rev. 1.0 (c) 1984 Jordan L. Chilcott,
Standard version tested with: AMODEM, AMIS, FORUM. (alias MDRIVE.XMO)
- SMARTMPP.DRV -- MPP Modem Driver Rev. 1.0S (c) 1984 Jordan L. Chilcott
Also supports "Smartmodem" features of MPP modems. (alias SMDRV.XMO)
- HOMEMPP.DRV -- MPP Modem Driver Rev. 1.0H (c) 1985 Jordan L. Chilcott
For use with HomePak HomeTerm. (aliases HMDRVE.XMO, HMDRV.XMO)
- MPPHNDLR.COM, by Trent Dudley, distributed with AMODEM 7.4 and 7.5, 1987.
"I have rewritten this MPP R: handler to make its relocation routine
compatible with SpartaDOS."
- MPP850.HAN, by James Dillow (author of DeTerm MPP), 1988.
- MPP.COM, by Bob Puff, modified version of MPP850.HAN by James Dillow,
distributed with BobTerm 1.10 (6/89), 1.20 (4/1990), & 1.21 (4/27/1990)

T: modem device handler on 1030 modem ROM

In addition to the ModemLink software program, the 1030 modem ROM also
contains the T: modem device handler that can be loaded and utilized by user programs apart from ModemLink.

The T: device handler does not use the SIO protocol for data transmission with the computer, creating potential conflict with other devices connected via
SIO that also don't use the SIO protocol, including the C: cassette handler built into the Atari OS. Consequently, there should be no program recorder attached to the system when using a T: modem device handler.

The handler supports tone dialing, but is not self-relocating, and thus must
be loaded before Atari BASIC is initialized. Extensive T: handler details published by Russ Wetmore: http://www.atarimagazines.com/v4n4/1030modem.html

Utilities to load the T: handler from the 1030 ROM include:
- AUTO1030.SYS, by Russ Wetmore for Antic, August 1985 (alias THANDLR1.030)
- BOOT1030.COM, by Trent Dudley, distributed with AMODEM 7.4 and 7.5, 1987

T: modem device handlers for both 835/1030/XM301 and 850-based modems

- '835/850 Handler' (alias AUTO1030.OBJ) by AMODEM author Jim Steinbrecher,
distributed with his Atari MODEM-835/850 Ver. 4.2, 01-15-84
- TSHANDL.OBJ, by Ken Fowkes, is the T: handler code extracted from his
DiskLink program (1984).

T: modem device handlers for the 835/1030/XM301 modems

- HANDLER.OBJ, by Atari, distributed with the XM301 modem on the XE Term disk.
A slight superset of the 1030 ROM T: handler; it too supports tone dialing
but is likewise not self-relocating. Shipped fall 1985.
- THANDLER.COM, by Trent Dudley, distributed with AMODEM 7.4 and 7.5, 1987.
A self-relocating version of the Atari XE Term T: handler.

R: modem device handlers for both 850-based and 835/1030/XM301 modems

- R.BIN, by Joe Miller and Russ Wetmore for Star Systems Software, 1984/5(?)
"A combined handler for 850-based and 835/1030 modems...an extensive
modification of Joe Miller's original handler from his...TSCOPE. While
TSCOPE uses a "T:" handler (standard for 835/1030 modems), R.BIN is
installed as an "R:" device." Self-relocating. Does not support tone
dialing on the 1030.
- RHANDLR1.030 is identical to R.BIN but also executes RUN "D:MENU" after
loading (perhaps for a disk of the month for an Atari user group).
- 'RHANDLER2' (RHANDLR2 or RHAND2.BIN or RHAND2.AUT) is a slightly modified
version of R.BIN which also executes the BASIC command RUN"D:*.RUN" after
loading.
- RHAN1030.AUT and RHAND3.BIN are two different derivatives of 'RHANDLER2'
where the provision to RUN"D:*.RUN" after loading has been removed.
- ATARISRS.232, by JM/RW, is the R.BIN driver code extracted from
VT-10-Squared, and then distributed with OmniCom, 1986-1987
- RBIN1030.BIN / RHANDLER.COM / R1030.XMO, by JM/RW/MG, are derivatives of
ATARISRS.232, possibly/probably modified for SpartaDOS compatibility by
Mike Gustafson. Distributed with AMODEM 7.4 and 7.5, 1987

R: modem device handlers for the 835/1030/XM301 modems

- SMARTT.COM, V7.14.86 by Joe Hitchens (author of VTERM)
- HANDLER.XM, by James Dillow (author of DeTerm XM301) (1988?)
- XM850.HAN, by James Dillow, based on his HANDLER.XM (1988?)
- XM.COM, by Bob Puff, modified version of XM850.HAN by James Dillow,
distributed with BobTerm 1.10, 6/1989
- XM.COM (re-written), by Bob Puff, distributed with BobTerm 1.20 (4/1990)
and 1.21 (4/27/1990)

R: modem device handlers for the R-Verter/SupraVerter Modem Adapter (SIO)

Note that handlers designed for the Atari SX212 modem via SIO may also work with the R-Verter/SupraVerter.

- The A.I.D. R-Verter was distributed with 4 different R: handler versions,
originally written by Royce W. Powell, (c) April, 1984 by A.I.D.:
- RHAND1.OBJ - R: handler supporting DSR & RD
- nearly identical: RVDOSXL.COM (version for DOS XL?)
- RHAND1C.OBJ - R: handler supporting DSR & CD
- RHAND2.OBJ - R: handler supporting DSR & RD and translation tables
- RHAND2C.OBJ - R: handler supporting DSR & CD and translation tables
- RVHAND.XMO or RVHAND.OBJ, by Ron Hodges, for use with HomePak HomeTerm.
A re-assembly of the file RHAND1C.SRC supplied with the R-Verter, but
starting at a lower address ($1D00).
- BOB-Verter 2.4 Fast Handler (RVERTER.COM), by Robert Puff, 10/16/89.
Explicitly supports both the SX212 modem (via SIO) and the R-Verter/
SupraVerter interface cable. Distributed with BobTerm 1.20 & 1.21

R: modem device handlers for the Datatari interface cable

- BTDATARI.COM, by ABBUC ev, specifically for use with BobTerm

R: modem device handlers for the SX212 modem connected via SIO

Note that handlers designed for the Atari SX212 modem via SIO may also work with the R-Verter/SupraVerter.

- The SX-212 Companion!, by Marc Ingle and Tom Neitzel of S*P*A*C*E,
based on the R-Verter R: handler, specifically to bring SX212 support to
850 Express! version 3.00p by Keith Ledbetter. Modifications by Tom Neitzel
and Marc Ingle. December, 1987. Two versions:
- LOADER.LOW (aliases: SX212A or SX212A.COM)
This version loads at $1D00 and works with most DOSes in their standard
configuration (generally 2 or 3 drives, with a LOMEM of $1D00 or lower).
- LOADER.HI (alias: SX212A.HI)
This version loads at $2000 and allows more memory for drive buffers
but will reduce your terminal buffer by about 750 bytes.
- SX_RHAND.COM, author/distribution unknown
- SX212HND.COM (alias SX212HND.OBJ), SX212 R: Handler V1.0 by Trent Dudley,
1987?
- HANDLER.OBJ, by Paul Swanson, distributed with Atari SX Express!, 1988
- SX212 ATH handler (SX212ATH.COM), by James Dillow (author of DeTerm SX212),
1988. (Distributed with AtariLink BBS.)
- SX.COM is a modified version by Bob Puff, distributed with BobTerm 1.10,
6/1989
- BOB-Verter 2.4 Fast Handler (RVERTER.COM), by Robert Puff, 10/16/89.
Explicitly supports both the SX212 modem (via SIO) and the R-Verter/
SupraVerter interface cable. Distributed with BobTerm 1.20 & 1.21
- SX.COM, by Robert Sinclair, distributed with ANSITERM, 1992

R: modem device handlers for the ATR8000 interface by SWP

- MYDOS 3.1x versions have an integrated ATR8000 R: handler
- MYDOS 4.50 includes:
- ATR232.AUT - RS-232 driver for the ATR8000
- ATR232HD.AUT - RS-232 driver for ATR8000 with ATR hard disk interface
- SpartaDOS from ICD (disk versions) shipped with an R: handler for the
ATR8000 called: AT_RS232

R: modem device handlers for the Multi I/O board (MIO) by ICD

The MIO includes its own 850 R: handler emulator in ROM, which does not need
to be loaded into computer RAM in order to function. Depending on the ROM version, this handler may or may not fully support the hardware flow control capability of the MIO hardware.

- HYPERSPD.MIO HyperSpeed RS-232 accelerator Version 1.3a for Multi I/O,
Copyright 1995, 1997 by Lenard R. Spencer. Full 19200-bit throughput
with hardware flow control.

R: modem device handlers for the Black Box interface by CSS

The Black Box includes its own 850 R: handler emulator in ROM, which does not need to be loaded into computer RAM in order to function. This handler supports the hardware flow control capability of the Black Box.

- HYPERSPD.BB HyperSpeed RS-232 accelerator Version 1.3a for Black Box,
Copyright 1995, 1997 by Lenard R. Spencer. Full 19200-bit throughput with
hardware flow control.

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

Subject: 8.1) How may a program behave on NTSC/PAL/SECAM computer versions?

Every Atari computer unit is designed for compatibility with either the NTSC, PAL, or SECAM analog color video encoding standards. Some functional characteristics vary among these versions of the computers, so that software may behave differently depending upon whether the computer it is run on is an NTSC, PAL, or SECAM computer.

PAL B and PAL I Atari computers differ only in the TV channel frequencies used by the RF signal produced. So in terms of software compatibility, all PAL Atari computers are indistinguishable.

The FGTIA found in SECAM Atari computers is designed to be 100% software compatible with the PAL GTIA. This fact, along with the fact that SECAM computer models include a PAL ANTIC, mean that the PAL and SECAM versions of the Atari computers are completely software compatible, but with one practical exception: in GTIA Graphics Mode 1 (BASIC Graphics mode 9), while the GTIA can display 16 distinct luminances, the FGTIA can only display 8 distinct luminances.

Thus the situation essentially simplifies down to just two sets of Atari computers that may have potential software compatibility issues between them: NTSC computers vs. PAL/SECAM computers. What might happen if you run a software program designed with an NTSC Atari on a PAL or SECAM Atari, or a program designed with a PAL or SECAM Atari on an NTSC Atari? There are a number of possibilities:

1) The program may run faster or slower than intended.

In order to work with the different timings of the NTSC and PAL/SECAM video signal standards, components of the NTSC versions of the Atari computers run
at slightly different speeds than they due on PAL/SECAM Atari computers. Software timing that is based exclusively on the CPU clock rate would thus run nearly 1% faster/slower on the opposite type of Atari. This effect, while small, can be significant in applications that are computation- or timing- sensitive, such as music players, or in any programs designed to simulate real time.

The screen refresh rate of the PAL/SECAM Atari computer is considerably slower than that of the NTSC Atari. A software rountine that operates as a Vertical Blank Interrupt (VBI), executed during the times between screen frame refreshes, is thus executed at considerably different frequencies on NTSC machines vs. PAL/SECAM machines. Based on this effect alone, a VBI programmed on an NTSC machine would run 16.8% slower on PAL/SECAM machines. Conversely,
a VBI programmed on a PAL/SECAM machine would run 20.2% faster on NTSC machines. (59.92Hz-49.86Hz=10.06Hz ; 10.06Hz/59.92Hz=16.8% ; 10.06Hz/49.86Hz=20.2%) These calculations ignore the above-mentioned CPU
clock rate differences, which would also come into play.

2) The program may exhibit some sort of "screen flickering" effect.

The ANTIC display list is the software program responsible for the video display, horizontal scan line by horizontal scan line. There are 262 lines available in the (non-interlaced) NTSC video signal, while there are 312 lines available in the (non-interlaced) PAL/SECAM video signal. If software written on a PAL/SECAM machine sets up an ANTIC display list that is made up of more scan lines than are available in the NTSC video standard, the program will exhibit a "screen flickering" effect if run on the NTSC Atari.

3) The system may crash.

NTSC and PAL/SECAM machines have different numbers of machine cycles available for execution of software routines designed as vertical blank interrupts (VBIs).

An Immediate VBI must complete execution within the number of machine cycles available during the vertical blank time:

NTSC: 2508 machine cycles
(262 NTSC scanlines - 240 Atari scanlines) * 114 cycles/scanline
PAL/SECAM: 8208 machine cycles
(312 PAL/SECAM scanlines - 240 Atari scanlines) * 114 cycles/scanline

8208 - 2508 = 5700
PAL/SECAM machines have a total of 5700 more machine cycles available for
Immediate VBIs than are available on NTSC machines.

A Deferred VBI must complete execution within the number of machine cycles available from one vertical blank to the next. The number of machine cycles available for a Deferred VBI depends upon the ANTIC Display List in use, but the upper limit may be derived from the total number of machine cycles per frame:
NTSC: 29859 machine cycles / frame
PAL/SECAM: 35568 machine cycles / frame

35568 - 29859 = 5709
PAL/SECAM machines could have as many as 5709 more machine cycles available
for Deferred VBIs than are available on NTSC machines.

If there are not enough machine cycles available on an NTSC machine to execute a VBI that was developed on a PAL/SECAM machine, the NTSC system will crash.

4) The colors displayed by the program are not what was intended.

When utilizing ANTIC graphics modes 2, 3, or F, NTSC Atari computers exhibit unique color artifacting effects that are not present on PAL/SECAM Atari computers. (Artifacting is discussed elsewhere in this FAQ list.) As a result, software that utilizes one of these high-resolution graphics modes can appear to be using very different colors on NTSC machines in comparison to PAL/SECAM machines.

Also, the additional color frequency generation circuitry present in PAL/SECAM machines produces a color palette that is similar to, though different from, the color palette of NTSC Atari computers. These differences are subtle
enough that they are generally not problematic.

5) The program may explicitly refuse to run on incorrect hardware.

Software may be designed to determine whether the Atari is NTSC or PAL/SECAM, and refuse to run if the hardware present does not match what is expected.

6) The program may not load correctly at all.

This would mostly likely result from copy protection techniques based upon precise hardware timing associated with disk drives, cassette recorders, or components of the computer itself, where the timing was not anticipated to
vary depending upon NTSC vs. PAL/SECAM hardware.

According to Jindroush (2/26/02), two examples of programs that run on NTSC machines but not PAL/SECAM machines as a result of timing-based copy
protection techniques (probably based on vblank timing) are Transylvania and The Quest, both by Penguin Software.

7) The program may run fine on both NTSC and PAL/SECAM machines.

Either the differences are too slight to matter, or the software may be sophisticated enough to detect NTSC vs. PAL/SECAM hardware, as described
above, and act accordingly.

An example of a program that alters its behavior depending upon detection of NTSC versus PAL/SECAM is Ghostbusters by Activision (checks the GTIA type).

=-=-=-=-=-=-=
Bottom line:

Software written for NTSC machines (North America) will (almost) always work
on PAL/SECAM machines (Europe), but software designed on PAL/SECAM machines sometimes won't work as intended on NTSC machines.

Replacing the NTSC ANTIC chip in an NTSC Atari with a PAL ANTIC changes the screen refresh rate to 50Hz, allowing most of the PAL/SECAM-only European software to run on a North American NTSC Atari. However, make sure your display device can support a 50Hz video refresh rate first!

North American Atari users might also obtain and use real European PAL or
SECAM Atari machines, with a similar caveat concerning the display device.

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

Subject: 8.2) What programming languages are available for the Atari?

Freddy Offenga has compiled a comprehensive list of programming languages produced for the 8-bit Atari. Please visit: http://www.ataripreservation.org/websites/freddy.offenga/langlist.txt

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Subject: 8.3) What cartridges were released for the Right Slot of the 800?

This should be a complete list of commercial cartridges produced for use in
the Right Cartridge slot of the Atari 800.

- ACE-80 by Claus Buchholz for Amiable Computer Enhancements / TNT Computing
(80 column editor, compatible with Atari BASIC, and patches available for:
OS/A+, EASMD, Letter Perfect v.6, Data Perfect, Atari Logo)
- Based on DT-80, the Atari/ATR8000 80-Column Dumb Terminal Emulator
cartridge by Claus Buchholz for Amiable Computer Enhancements, 1984
- Adapta-Cartridge B: by Microsota, Inc.
- Austin 80 Console Software by Austin Franklin Associates
(for use with the Austin 80 Column Video Processor Board)
- Block (first right cartridge; first "backup" program hardware device)
- Cartridge Maker by Radical Systems (EPROM burner)
- KISS by Eastern House
- Magic Dump by Geminisoft/Eric Wolz for Sar-An Computer Products (SCP)
- Magic Dump II by Geminisoft/Eric Wolz for Sar-An Computer Products (SCP) - Monkey Wrench by Eastern House
- Monkey Wrench II (original 800 version) by Eastern House
- Note: There is also a Monkey Wrench II for Atari XL version that works
with XL/XE computers except 1200XL
- R-Time 8 by ICD (battery-backed clock, for left or right cartridge slots)
- Real Time Cartridge by Sunmark
- Right Cartridge which boots the Atari from the Corvus disk system.
(by ????? Details????)

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Subject: 8.4) What games support 4 or more simultaneous players?

Section started by Andreas Koch; See also this thread at AtariAge: http://www.atariage.com/forums/topic/155696-4-player-simultaneous-games/

a) The following games support 4 joystick head-to-head play:
(Only possible on the 400/800 since only these computer models have
4 controller ports)

- Ali Baba and the Forty Thieves by Stuart Smith for Quality Software
- Aliens a public domain game by ??? using an altered Dandy program
(the Dandy font and thus the graphics were changed, however,
the levels remain the same and can be used in both games)
- Asteroids by Tod Frye for Atari
- Basketball by Alan Miller for Atari
- Battle Room (CIA vs. KGB) a public domain game by SNACC
- Dandy disk by John H. Palevich (Jack Palevich) for APX
- Depth Warrior by ??? for ROM magazine (Canada) v1n7 ***
- Floyd of the Jungle by MicroProse (1982 and 1983 releases)
- GEM by Joel Gluck
- Killa Cycle by Simon Goodwin & David Muncer
- Hockey by Gamma Software, (c)1981
- Major League Hockey by Thorn EMI
- Major League Soccer by Thorn EMI
- Maze War by ???
- Mouse Party by Bill Halsall for New Atari User #39 Aug/Sep 1989
- M.U.L.E. by Ozark Softscape for Electronic Arts
- The Return of Heracles by Stuart Smith for Quality Software
- Road Block / Roadblock by Brian Holness for Compute! v5n7 #38 July 1983
- Silicon Warrior, developed by The Connelley Group for Epyx
- Sky Warrior by Jack Chung for ROM magazine (Canada) v1n6
- Soccer by Gamma Software
- Survivor by Richard Carr for Synapse
- Tank Battle by Fred Pinho from Antic magazine:
http://www.atarimagazines.com/v3n2/animate.html
- Volleyball by ??? (public domain game written in Atari BASIC)
- Yellow-Brick-Road by ??? for ROM magazine (Canada) v1n2 ***

*** these programs are reported to be 4-player programs, I'm
not sure if they are meant to be 4-players simultaneously

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