Atari 800XL
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| Atari 800XL home computer | |
| Specifications | |
|---|---|
| Manufacturer | Atari, Inc. |
| Type | Home computer |
| Released | 1983 |
| Intro price | US$299 (1983) |
| CPU | MOS Technology 6502C @ 1.79 MHz (NTSC) / 1.77 MHz (PAL) |
| Memory | 64 KB RAM (eight 64K x 1 DRAMs); 24 KB ROM (16 KB OS + 8 KB BASIC Rev. B) |
| Storage | Cassette (1010) or 5.25" floppy disk drive (1050) over SIO; ROM cartridge |
| Display | 40 x 24 text, up to 320 x 192 pixels; RF and 5-pin DIN monitor output |
| Sound | POKEY: four audio channels |
| OS / Firmware | Atari XL Operating System; Atari BASIC Rev. B in ROM |
| Predecessor | Atari 800 |
| Successor | Atari 65XE |
| Model no. | 800XL |
The Atari 800XL is the full-memory model of Atari's XL range, announced with the Atari 600XL in June 1983 and sold as the direct replacement for the 1200XL at US$299.[1] It became the most widely sold Atari 8-bit computer.
Atari's own field service manual for the machine is the source for the hardware detail, the component locations, the connector pinouts and the supply ratings below.[2]
Architecture and processor
The 800XL uses the 6502C at 1.79 MHz (NTSC) or 1.77 MHz (PAL), with a single +5 V DC requirement and an integral clock circuit.[2] The main board carries 64 KB of RAM, a 16K x 8 operating-system ROM and an on-board Atari BASIC ROM; the console has a keyboard with four function keys including a HELP key, a RESET key, a detachable RF television cable, an SIO jack, controller jacks, a single cartridge slot, a power LED, a 5-pin DIN monitor jack and a parallel bus interface.[2]
| Position | Device | Atari part number |
|---|---|---|
| U1 | LM358 dual op-amp | C061702 |
| U2 | 74LS138 decoder | C061428 |
| U3 | MMU1B memory management unit | C061618 |
| U4 | 8K x 8 Atari BASIC Rev. B ROM | C060302 |
| U5 | 16K x 8 operating system ROM | C061598 |
| U7 | ANTIC | C021697 |
| U8 | 6502C CPU | C014806 |
| U9-U16 | 64K x 1 DRAM (eight devices) | C060612 |
| U17 | GTIA | C014805 |
| U18 | 74LS08 quad AND | C017097 |
| U19 | 74LS14 hex inverter | C061850 |
| U20 | CD4050B hex buffer | C010816 |
| U22 | POKEY | C012294 |
| U23 | PIA | C014795 |
| U24, U25 | CD4051B keyboard sense/scan multiplexers | C014336 |
| U26, U27 | 74LS158 multiplexer | C014345 |
| U28 | 74LS375 latch | C060619 |
| U29 | Delay module | C060472 |
| U30 | 74LS51 AND/OR inverter | C060474 |
The crystal Y1 is 3.579545 MHz.[2] Positions U6 and U21 are marked "(not used)" in Atari's parts list, as are a number of capacitor, resistor and inductor positions - an unpopulated footprint on an 800XL board is usually factory-correct, not a missing part.[2]
Memory
- 64 KB RAM - eight 64K x 1 DRAMs at U9-U16[2]
- 24 KB ROM - a 16K x 8 operating system ROM at U5 and an 8K x 8 Atari BASIC Rev. B ROM
at U4. Built-in BASIC behaves as a permanently fitted cartridge; a cartridge in the slot takes precedence over it in hardware.[2]
All of the operating system is shadowed by RAM on 64 KB XL and XE machines, which is what makes a RAM-based operating system - and the "Translator" load of the older 400/800 Rev. B operating system for incompatible software - possible.[3][4]
Display, video output and sound
Graphics are produced by ANTIC and GTIA: text up to 40 x 24, bitmap modes up to 320 x 192 pixels, four players and four missiles with collision detection, and programmable display lists with smooth scrolling.
The 5-pin DIN monitor jack (J2) carries composite video and composite luminance from the GTIA video summation circuitry and amplified mono audio from POKEY. Atari specifies the following output levels:[2]
| Signal | Minimum | Maximum |
|---|---|---|
| Composite video | 750 mV p-p | 1 V p-p |
| Composite luminance | 1.2 V p-p | 1.5 V p-p |
| Audio | 600 mV p-p | 750 mV p-p |
The RF modulator (UM1652) produces 1-2 mV into 75 ohms, with the audio carrier 4.5 MHz above the video carrier; channel 2 uses a 55.25 MHz video carrier and channel 3 a 61.25 MHz one.[2]
POKEY provides four audio channels, keyboard scanning, serial I/O and a random-number generator.
Input, output and expansion
- Cartridge slot - 30-pin connector (C014389)[2]
- SIO port - 13-pin right-angle connector (J1, C012995), maximum 19.2 kbaud[2]
- Two controller jacks - 9-pin right-angle (C010448); pin 7 is +5 V and pin 8 ground[2]
- Monitor jack - 5-pin DIN (J2, C014388)[2]
- Parallel Bus Interface - 50-pin edge connector on the rear
- Power in - 7-pin DIN (C061838)[2]
- Keyboard header - 24-pin (C061793)[2]
The XL machines have only two controller jacks where the 400 and 800 had four. The PIA's PORTB, which used to serve jacks 3 and 4, is used on the XL for switching the operating system and BASIC in and out and for invoking the self tests.[3]
Keyboard
A 3/4-stroke, 56-key keyboard: 55 alphanumeric keys including special characters and controls, a space bar, four function keys and RESET. The matrix is read through the two CD4051B sense/scan decoders at U24 and U25.[2] (The equivalent parts on the 600XL are at U22 and U23.[5])
HELP returns to the main self-test menu from an individual test. Holding OPTION at power-on disables the built-in BASIC, and with no cartridge or diskette present the self-test menu appears.[2]
Power
The 800XL takes +5 V DC through a 7-pin DIN connector on the rear panel, Atari part C061838. The external supply accepts 110 V AC nominal and provides +5 V DC, +/-2%, rated 1.2 A maximum.[2]
The 800XL is a +5 V only machine. There is no +12 V rail, no 7812 and no on-board regulator or rectifier of any kind: Atari's parts list for the board contains none. The XL line was the first Atari computer family to need only a single 5 V DC supply.[2][3]
 | Descriptions of the 800XL power input as a "5.5 mm / 2.1 mm centre-positive barrel
jack" are wrong; it is a 7-pin DIN. Measure any replacement brick at the plug before connecting it. With no regulator on the board, an over-voltage supply goes straight to the custom chips.[2] |
Checking a machine
PRINT PEEK(65527)from BASIC returns 2 on an 800XL, 1 on a 600XL,
10 or 11 on a 1200XL and 221 or 255 on a 400 or 800.[3]
- Hold OPTION at power-on with no cartridge or disk to reach the self-test menu; press
HELP to return to the menu from a test.[2]
- Atari's deeper diagnostic for this machine is the SuperSALT test assembly with jumper
cables and a power supply.[2]
Schematics and service manual
| Logic board schematics | Field service manual |
|---|---|
| File:Atari 800XL Schematics.pdf | File:Atari 800XL Service Manual.pdf |
The manual is also available as a page: Atari 800XL Service Manual.
Related pages
- Atari 800XL General Maintenance
- Atari 800XL Troubleshooting Guide
- Atari 800XL Capacitor Replacement Guide
- Atari 600XL
- Atari 65XE
References
- ↑ "The Atari 1400XL Computer Systems", Atari Museum (Curt Vendel): "In June of 1983 Atari would follow up from the announcements of the 600XL and 800XL with its other computers", and the 800XL was to be the 1200XL's direct replacement "in a much more affordable design at $299". Secondary source.
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 2.19 2.20 2.21 Atari, Inc., ATARI 800XL Computer Field Service Manual. Section 1 (theory of operation, monitor output levels, power supply, connector pin assignments) and the parts list. Hosted on this wiki: File:Atari 800XL Service Manual.pdf.
- ↑ 3.0 3.1 3.2 3.3 Robert DeWitt, "Inside Atari: Evolution of the XL Computers", Antic Vol. 3 No. 2 (June 1984), reproduced at atarimagazines.com. Source for the loss of the third and fourth joystick ports, the single 5 V supply, the 600XL having no monitor output, and the PEEK(65527) operating-system revision values.
- ↑ Matthew Ratcliff, "First Look Inside the XE Game System", Antic Vol. 7 No. 4 (August 1988), reproduced at atarimagazines.com. Source for the DB15 keyboard connector, the two 64K x 4 DRAMs and 17-chip count, the built-in Missile Command bank-switching and the XG-1 light-pen register behaviour.
- ↑ Atari, Inc., ATARI 600XL Computer Field Service Manual, FD100610 Rev. 1, October 1983. Section 1 (theory of operation, power supply, connector pin assignments), Section 5 (parts list with designators and Atari part numbers). Hosted on this wiki: File:Atari 600XL Field Service Manual.pdf.