Atari 800 Home Computer (1979)

Features

CPU: MOS 6502 1.79MHz
Co-Processors: ANTIC (Scrolling, Sprites, Video), CTIA / GTIA (Color, Sprites, Collisions), POKEY (Timers, Sound, Keyboard, Serial I/O), PIA 6810 (I/O including controller ports)
RAM: 8K base, up to 48K (with memory expansion boards)
ROM: 10K
Display: 24 x 40 text, 320 x 192 monochrome, 160 x 96 with 128 colors
Expansion: 4 internal expansion slots, 2 cartridge slots
Ports: 4 controller ports, RGB video output, TV video output
Keyboard: QWERTY full stroke keyboard with 62 keys, 4 function keys (Reset, Option, Select, Start)
Storage: external 5.25” floppy drive, cassette recorder
OS: Atari OS

Usage

Currently, MESS supports the following Atari 800 versions:

a800 [Atari 800 (NTSC)]
a800pal [Atari 800 (PAL)]

Both drivers support up to two cart slots for cart dumps in .rom and .bin format, using the “cartridge1” (cart1) and “cartridge2” (cart2) devices, and up to four floppy drive for disks in .atr, .dsk and .xfd format, “floppydisk1” (flop1) to “floppydisk4” (flop4).

Keyboard

These systems require full keyboard emulation to work correctly. At startup, full keyboard emulation mode is enabled by default. Whilst in full keyboard emulation mode, some key associated functionality may be disabled (like the ESC key for EXIT). The keyboard emulation mode is toggled using the “Scroll Lock” key (by default).

Original Keyboard: QWERTY full stroke keyboard, 62 keys plus 4 function keys on the right

CLEAR   INSERT   DELETE                   SYSTEM
  ESC    1!   2"   3#   4$   5%   6&   7'   8@   9(   0)    <        >     BACK S   BREAK            RESET
  
CLF  SET                                                     UP _    DOWN |
  TAB      Q    W    E    R    T    Y    U    I    O    P      -        =          RETURN           OPTION
  
                                                                LEFT \  RIGHT ^     CAPS
     CTRL    A    S    D    F    G    H    J    K    L     ;:      +        *       LOWR            SELECT
  
  
     SHIFT     Z    X    C    V    B    N    M    ,[     .]    /?     ATARI        SHIFT             START
  
  
                                   SPACE

Keys “TAB”, ”-”, ”=”, ”+” and “*” have 3 functions.

Known Issues

Most disk and cartridge images should work, though some graphic issues may exist.

History and Trivia

The Atari 400 and 800 were the first home computers to use custom coprocessors and the first to use “sprites” and special video interruptions like display lists, features that will be implemented several years after on the Commodore Amiga. It offered high graphic resolution, lots of colors and great sound capabilities, more than other computers could do then! The two models had same characteristics, but the 800 had 48 KB of RAM (instead of 16 kb), two cartridge ports (only one for the 400) and a proper mechanical keyboard (a membrane keyboard for the 400).

In fact the very first Atari 800 Computers were shipped with 8 or 16 KB memory, expandable to 48 KB. After initial release, the 800 came standard with 48 KB memory.

Prior to production, the 800 was known inside Atari as code name “Colleen”. It is rumored that Colleen and Candy (the 400 code name) were actually secretaries at Atari.

Many peripherals were product for the 800. Among these we recall: Atari 810 floppy drive, Atari 820 impact dot-matrix printer, Atari 850 Interface Module, Atari 830 Acoustic Couple Modem and Atari 835 Direct Connect Modem.

The floppy drive uses single-sided 5 1/4-inch floppy disks, holding 90K of data on a disk. The data is transfered in serial format at 19200 baud. Up to 4 drives can be hooked up.

The printer can produce 40 columns of 5×7 characters, at approximately 40 characters per second.

The 810 and 820 are considered “intelligent” peripherals - they have built-in processor chips which lighten the load on the computer's main processor. They can each be plugged directly into the Atari 400 or 800, with no other inteface required.

The Interface Module provides 4 separate RS-232-C serials ports and a single Centronics compatible printer port. It plugs into one of the controller jacks on the computer, which are actually both input/output, analog and digital ports. The Acoustic Couple Model requires both the Atari 850 Interface Module and the TeleLink I ROM cartridge to operate. On the other hand, the Direct Connect Modem requires only the Atari Telelink II ROM cartridge (and not the Interface Module) to operate.

Additional accessories include the external keypad, for fast data entry and the cassette tape drive, cheaper than the floppy drive but less reliable too.

In 1983, Atari released the 800XL computer. It has the same CPU as the Atari 800, and runs at the same speed. Basically a cheaper version of the 800, it is supposed to be compatible with all Atari 800 software and peripherals, but it isn't. Improvements include: 64K base RAM vs. 8K, parallel I/O port (PBI), general purpose I/O port.

(info from old-computers.com)