Atari 800XL
.jpg) | |
| Atari 800XL home computer | |
| Specifications | |
|---|---|
| Manufacturer | Atari, Inc.; later Atari Corporation |
| Type | Home computer |
| Released | 1983 (announced at the Summer CES, June 1983)[1] |
| Discontinued | 1985[1] |
| Intro price | US$299 (announced June 1983)[1] |
| CPU | 6502C (SALLY), 1.79 MHz NTSC / 1.77 MHz PAL |
| Memory | 64 KB RAM (eight 64K × 1 DRAMs); 16 KB operating system ROM and 8 KB Atari BASIC ROM |
| Storage | Cassette or 5.25" floppy disk drive over SIO; ROM cartridge |
| Display | 40 × 24 text, up to 320 × 192 pixels; RF and 5-pin DIN monitor output |
| Sound | POKEY: four audio channels |
| OS / Firmware | Atari XL Operating System; Atari BASIC Rev. B (Rev. C on late PAL boards) built in |
| Predecessor | Atari 800, Atari 1200XL |
| Successor | Atari 65XE, Atari 800XE |
| Model no. | 800XL |
The Atari 800XL is the 64 KB model of Atari's XL range. Atari introduced it with the Atari 600XL at the Summer CES in June 1983, at a retail price of US$299, and announced that the 400, 800 and 1200XL would be discontinued.[1] It keeps most of the 1200XL's features but has built-in Atari BASIC and a parallel bus interface, and drops the 1200XL's four function keys and two LEDs.[1]
Atari's field service manual for the machine, FD100740 Rev. 01 of February 1984, is the source for the hardware detail below.[2]
History and versions
[edit | edit source]Atari, Inc. built NTSC and PAL 800XLs from autumn 1983 to summer 1984, in Hong Kong and Taiwan, with Atari BASIC Revision B and no chroma signal on pin 5 of the monitor socket. Atari Corporation built a PAL version on the "800XLF" board from autumn 1984, with the FREDDIE memory controller and BASIC Revision C; later production of that board added chroma on monitor pin 5. A SECAM version for France has its own board with the FGTIA, a six-pin monitor socket and no RF output. Production ended by 1985.[1] Atari cut the US price from US$250 to US$179 in August 1984 and to US$119 later that year.[1]
Architecture
[edit | edit source]The 800XL is a single-board machine built around the 6502C, with ANTIC, GTIA, POKEY and the PIA. It runs from a single +5 V DC supply.[2][3]
| Position | Device | Atari part number |
|---|---|---|
| U1 | LM358 dual op-amp | C061702 |
| U2 | 74LS138 decoder | C061428 |
| U3 | MMU 1B memory management unit | C061618 |
| U4 | 8K × 8 Atari BASIC ROM, Rev. B | C060302 |
| U5 | 16K × 8 operating system ROM | C061598 |
| U7 | ANTIC | C021697 |
| U8 | 6502C CPU | C014806 |
| U9–U16 | 64K × 1 DRAM | 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 multiplexers | C014336 |
| U26, U27 | 74LS158 multiplexers | C014345 |
| U28 | 74LS375 latch | C060619 |
| U29 | Delay module | C060472 |
| U30 | 74LS51 AND/OR inverter | C060474 |
Atari's schematic draws U4 as the 8K BASIC ROM and U5 as the 16K operating system ROM (a 27128 type); its parts list prints the two the other way round.[2] Y1 is the 3.579545 MHz crystal (C061090) on domestic boards; the schematic's notes give 3.546894 MHz (C015510) for the U.K. version, and the domestic RF modulator is a UM1652 (CA061619).[2] U6 and U21 are not fitted.[4]
Memory
[edit | edit source]The 800XL has 64 KB of RAM in eight 64K × 1 DRAMs at U9–U16, a 16 KB operating system ROM and an 8 KB Atari BASIC ROM.[2] Built-in BASIC behaves like a permanently fitted cartridge, and a cartridge in the slot takes precedence over it. The memory management unit decodes address lines A8–A15, with the ROM-enable signal from the PIA and ANTIC's refresh, into the select signals for the chips, the ROMs, the DRAMs, BASIC and the cartridge.[2]
The RAM also lies under the operating system ROM. Switching the ROM out lets a different operating system run from RAM, which is how Atari's Translator disk loads the 400/800 Revision B operating system for older software that does not run on the XL.[3]
Display, video output and sound
[edit | edit source]ANTIC and GTIA give text up to 40 × 24, bitmap modes up to 320 × 192 pixels, four players and four missiles with collision detection, and programmable display lists.[2]
The 5-pin DIN monitor socket (J2) carries composite video and composite luminance from the GTIA video summation circuit and amplified audio from POKEY. Atari gives these 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 |
Into 75 Ω the RF modulator gives 1–2 mV, with the sound carrier 4.5 MHz above the vision carrier: 55.25 and 59.75 MHz on channel 2, 61.25 and 65.75 MHz on channel 3.[2]
POKEY provides four audio channels and also scans the keyboard and drives the serial port.[2]
Input, output and expansion
[edit | edit source]| Position | Connector | Atari part number |
|---|---|---|
| J1 | SIO, 13-pin right-angle; 19.2 kbaud maximum | C012995 |
| J2 | Monitor, 5-pin DIN | C014388 |
| J4 | Cartridge, 30-pin | C014389 |
| J5, J6 | Controller jacks, 9-pin right-angle | C010448 |
| J7 | Power, 7-pin DIN | C061838 |
| J8 | Keyboard header, 24-pin | C061793 |
The parallel bus interface is an edge connector at the rear that gives unbuffered access to the address, data and control lines.[2] On the SIO port, pin 10 is +5 V/ready and pin 12 is not connected on the XL and XE machines; the 400 and 800 put +12 V on pin 12.[1]
The XL machines have two controller jacks where the 400 and 800 had four. Port B of the PIA, which served jacks 3 and 4, is used on the XL to switch the operating system and BASIC in and out and to start the self test.[3]
Keyboard
[edit | edit source]The keyboard is a 3/4-stroke, 56-key unit with START, SELECT, OPTION, HELP and RESET keys, connected to the board by a 24-way ribbon.[2] The matrix is read through the CD4051B multiplexers U24 and U25 by POKEY.[2]
Holding OPTION at power-on disables built-in BASIC, and with no cartridge or disk the self-test menu appears. HELP returns from an individual test to the menu; Atari notes that it does not work as on the 1200XL.[2]
Power
[edit | edit source]The 800XL takes +5 V DC through the 7-pin DIN socket J7. Atari's external supply (CA024814-001) takes 110 V AC nominal and delivers +5 V DC ±2 % at up to 1.2 A.[2] On the schematic, pins 1, 4 and 6 of J7 are +5 V, pins 3, 5 and 7 ground and pin 2 the shield; the switched supply is filtered on the board into +5A, +5B and +5C.[2]
The board has no rectifier, regulator, +12 V or −5 V supply; the XL machines were the first Atari computers to need only a single 5 V DC supply.[2][3]
 | The power input is a 7-pin DIN, not a barrel jack. Nothing on the board regulates the 5 V, so measure a replacement supply at its plug before connecting it.[2] |
Checking a machine
[edit | edit source]PRINT PEEK(65527)returns 2 on an 800XL and 1 on a 600XL.[3]- The built-in self test covers RAM, ROM and ANTIC; ANTIC, GTIA and POKEY; and the keyboard. The memory test shows two bars for the 16 KB operating system ROM and 48 blocks of 1 KB RAM; the other 16 KB of RAM is not tested.[2]
- Atari's field test used the SuperSALT diagnostic cartridge (FD100335) with the SuperSALT test assembly (FA100332).[2]
Fault-finding is on the Atari 800XL Troubleshooting Guide.
Schematics and service manuals
[edit | edit source]- Atari's own manual: 800XL Computer Field Service Manual, FD100740 Rev. 01 (February 1984), with the schematic, silkscreen and parts list.
- Atari 800XL Service Manual: a third-party manual by Electronic Dimensions that follows Atari's material and adds a parts list marking unfitted positions.[4]
- Atari 800XL Schematics: a KiCad redrawing dated 15 January 2020, "based on Atari 800 XL Service Manual"; not an Atari drawing.
| Field service manual | Redrawn schematics |
|---|---|
| File:Atari 800XL Computer Field Service Manual FD100740 Rev 01.pdf | File:Atari 800XL Schematics.pdf |
Related pages
[edit | edit source]- Atari 800XL General Maintenance
- Atari 800XL Troubleshooting Guide
- Atari 800XL Capacitor Replacement Guide
- Atari 600XL
- Atari 65XE
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Michael D. Current (ed.), Atari 8-Bit Computers: Frequently Asked Questions, comp.sys.atari.8bit FAQ, last modified 29 November 2009, section 1.6 "What is the Atari 800XL?", section 1.16 (port pinouts) and the history timeline for 1983–1985. faqs.org. Community reference, used for dates, prices and board versions.
- ↑ 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 Atari, Inc., 800XL Computer Field Service Manual, FD100740 Rev. 01, February 1984. Section 1 (theory of operation, pp. 1-1 to 1-15), Section 2 (testing), Section 3 (symptom checklist), Section 4 (disassembly), Section 5 (schematic, silkscreen and parts list). Hosted here as File:Atari 800XL Computer Field Service Manual FD100740 Rev 01.pdf.
- ↑ 3.0 3.1 3.2 3.3 3.4 Robert DeWitt, "Inside Atari: Evolution of the XL Computers", Antic Vol. 3 No. 2 (June 1984), atarimagazines.com. Source for the single 5 V supply, the loss of joystick ports 3 and 4, the 64 KB RAM underlay and Translator disk, and the PEEK(65527) values.
- ↑ 4.0 4.1 Electronic Dimensions, Service Manual for the ATARI 800XL Computer (San Luis Obispo, California, c. 1984), Section 5 parts list, pp. 32–36, which marks unfitted positions "(not used)". Third-party publication. Hosted here as Atari 800XL Service Manual.