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Top Document: Atari 8-Bit Computers: Frequently Asked Questions
Previous Document: 0.1) Table of contents
Next Document: 1.2) What is the Atari 400?
1.1) What is an Atari 8-bit computer?
Based in Silicon Valley in the U.S.A., the company known as Atari produced
a line of home computers from 1979 to 1992 often referred to collectively as
the "Atari 8-bits," the "8-bit Ataris," the "400/800/XL/XE series," etc.
The computers included the 400, 800, 1200XL, 600XL, 800XL, 65XE, 130XE, 800XE,
and the XE video game system.
Notable home computers that were introduced before the Atari 400/800:
1977: Apple II, Tandy Radio Shack TRS-80 (Model I), Commodore PET
Notable home computers that were introduced after the Atari 400/800:
1979: Texas Instruments TI-99/4
1980: Commodore VIC-20, TRS-80 Color Computer, Osborne 1
1981: Texas Instruments TI-99/4A, IBM PC, Sinclair ZX81 / TS 1000, BBC Micro
1982: Kaypro II, Sinclair ZX Spectrum, Commodore 64
1983: Coleco Adam, MSX
1984: Apple Macintosh, Amstrad CPC
1985: Atari ST, Commodore Amiga
1987: Acorn Archimedes
In marketing their computers to the public, Atari always had to contend with
their company history and reputation as a maker of video games. While the
8-bit Atari computers in their heyday were technically quite comparable if not
superior in the worlds of home and business personal computing, they also live
up to the name "Atari" with a huge library of video games which were often
outstanding for their time.
The 8-bit Atari computers do not use the same cartridges or floppy disks as
any other Atari platforms, such as the 2600 Video Computer System (VCS), the
5200 SuperSystem, the 7800 ProSystem, or the ST/TT/Falcon computers. All of
these but the 5200, however, do share the same joystick/controller hardware
port.
The 5200 SuperSystem is actually nearly identical to the 8-bit computers
internally, yet cartridges for the 5200 and the 8-bit computers cannot be
exchanged, primarly due to the physically different cartridge ports.
Here are some of the performance specifications of the 8-bit Atari computers:
(Some of the rest of this section by Bill Kendrick)
CPU: 6502 (MOS Technology)
CPU CLOCK SPEED:
NTSC machines: 1.7897725 MHz
non-NTSC machines: 1.773447 MHz
SCREEN REFRESH RATE:
59.94 Hz (NTSC machines) or 49.86 Hz (PAL machines)
GRAPHICS MODES:
ANTIC CIO/BASIC Display Resolution Number of
Mode # Graphics # Type (full screen) Colors
---------------------------------------------------------------
2 0 Char 40 x 24 1 *
3 - Char 40 x 19 1 *
4 12 ++ Char 40 x 24 5
5 13 ++ Char 40 x 12 5
6 1 Char 20 x 24 5
7 2 Char 20 x 12 5
8 3 Map 40 x 24 4
9 4 Map 80 x 48 2
A 5 Map 80 x 48 4
B 6 Map 160 x 96 2
C 14 ++ Map 160 x 192 2
D 7 Map 160 x 96 4
E 15 ++ Map 160 x 192 4
F 8 Map 320 x 192 1 *
F 9 + Map 80 x 192 1 **
F 10 + Map 80 x 192 9
F 11 + Map 80 x 192 16 ***
* 1 Hue; 2 Luminances
** 1 Hue; 16 Luminances
*** 16 Hues; 1 Luminance
+ require the GTIA chip. 1979-1981 400/800's shipped with CTIA
++ Not available via the BASIC GRAPHICS command in 400/800's.
GRAPHICS INDIRECTION (COLOR REGISTERS AND CHARACTER SETS):
Nine color registers are available. Each color register holds any of 16
luminances x 16 hues = 256 colors. (Four registers are for player-missile
graphics.
Character sets of 128 8x8 characters, each with a normal and an inverse
video incarnation, are totally redefinable.
PLAYER-MISSILE GRAPHICS: (byte height and OR corrections from Piotr Fusik)
Four 8-bit wide, 120 or 240 byte high single color players, and four
2-bit wide, 120 or 240 byte high single color missiles are available.
A mode to combine the 4 missiles into a 5th 8-bit wide player is also
available, as is a mode to OR colors or blacken out colors when players
overlap (good for making three colors out of two players!) Players
and missiles have adjustable priority and collision detection.
DISPLAY LIST INTERRUPTS (DLI's):
Screen modes can be mixed (by lines) down the screen using the Display
List - a program which is executed by the ANTIC graphics chip every
screen refresh:
All other screen attributes (color, player/missile horizontal position,
screen width, player/missile/playfield priority, etc.) can be ajusted
at any point down the screen via DLI's.
SCROLLING:
Fine scrolling (both vertical and horizontal) can be enabled on any
line on the screen.
SOUND:
Sound is monaural/monophonic (one channel output).
Up to 4 separate simultaneous voices can be produced, configured as one of
the following:
- 4 voices, each with one of 256 unique frequencies/pitches
- 2 voices, each with one of 65,536 unique frequencies/pitches
- 1 voice with one of 65,536 pitches and 2 voices with one of 256 pitches
Each voice may be produced with one of 8 available "noise" settings/
polynomial-counter combinations, commonly called "distortion" settings.
(There are actually only 6 distinct combinations of 3 poly-counters
offered, but one of the poly-counters has 2 available settings itself,
resulting in 2 additional noise settings for the total of 8 available.)
Each voice may be produced at one of 16 volumes.
Direct control of the position of the speaker cone is also available, with
4-bit (16 position) resolution. Known as "volume only mode" on the Atari.
A fifth "voice" is produced as a separate signal by the internal speaker
on the Atari 400/800. This is typically used only for keyclick and
buzzer. In XL/XE systems these sounds are output as part of the normal
monaural audio output signal.
Top Document: Atari 8-Bit Computers: Frequently Asked Questions
Previous Document: 0.1) Table of contents
Next Document: 1.2) What is the Atari 400?
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Last Update July 09 2008 @ 00:12 AM