Atari 1040ST
 | |
| Specifications | |
|---|---|
| Manufacturer | Atari Corporation |
| Type | Home computer |
| Discontinued | 1990 |
| CPU | Motorola MC68000 @ 8 MHz |
| Memory | 1 MB RAM |
| Storage | Internal 3.5″ DS/DD 720 KB floppy drive |
| Display | 320×200 (16 colours), 640×200 (4 colours), 640×400 (mono) |
| Sound | Yamaha YM2149F (3 voices + noise) |
| OS / Firmware | Atari TOS (GEM desktop) |
| Predecessor | Atari 520ST |
| Successor | Atari 1040STE |
The Atari 1040ST (also sold as the 1040STF and 1040STFM) is a home computer manufactured by Atari Corporation, released in 1986. It was the first home computer to ship with 1 MB of RAM as standard, and the first personal computer to break the US$1-per-kilobyte price barrier for memory.[1] Built around a Motorola 68000 processor clocked at 8 MHz, the 1040ST ran Atari TOS with the GEM graphical desktop environment and included built-in MIDI ports, making it widely adopted for music production throughout the late 1980s.
History
[edit | edit source]The Atari ST line originated from Jack Tramiel's acquisition of Atari Inc.'s consumer division from Warner Communications in July 1984. Tramiel, who had recently departed Commodore International, tasked engineer Shiraz Shivji with designing a new 16/32-bit computer. The 520ST was designed in roughly five months and shown at the January 1985 Consumer Electronics Show (CES).[2]
The earliest 520ST units shipped with TOS loaded from floppy disk, as the operating system ROM was not yet finalised. By late 1985, TOS was burned into ROM chips, eliminating the need for disk-based loading. In 1986, Atari introduced the STF variants with integrated floppy disk drives: the 520STF (single-sided drive, 360 KB) and the 1040STF (double-sided drive, 720 KB). The 1040STF was the first model to ship with a full megabyte of RAM.
The "F" designation indicates a built-in floppy drive. Later models added "M" for a built-in RF modulator (the 1040STFM), enabling television output without an external monitor. The naming convention is:
- 1040ST — base designation, 1 MB RAM, no internal floppy
- 1040STF — 1 MB RAM, internal double-sided floppy drive
- 1040STFM — 1 MB RAM, internal floppy drive, built-in RF modulator
In practice, most 1040ST-series machines sold were either STF or STFM models. The 1040ST was positioned at US$999.99 including a colour monitor, or US$799.99 with the monochrome SM124 monitor, undercutting the Apple Macintosh Plus by a wide margin.
The ST "officially stands for 'Sixteen/Thirty-two', referring to the Motorola 68000's 16-bit external data bus and 32-bit internal architecture.[3]
Technical Specifications
[edit | edit source]| Component | Specification |
|---|---|
| CPU | Motorola MC68000FN8, 8 MHz, DIP-64 package. 16-bit external data bus, 32-bit internal registers, 24-bit address bus (16 MB addressable). |
| RAM | 1024 KB (1 MB) using sixteen 41256 (256K×1) DRAM chips, or in later revisions, fewer higher-density chips. |
| ROM | 192 KB TOS in six 32K×8 ROM/EPROM ICs (early boards) or two 128K×8 ROMs (later boards). TOS versions 1.00, 1.02, or 1.04 depending on production date. |
| Video (Shifter) | Atari custom Shifter IC (C025914). Three display modes: low resolution 320×200 (16 colours from 512-colour palette), medium resolution 640×200 (4 colours from 512), high resolution 640×400 monochrome (~71.2 Hz vertical refresh, requires SM124 monitor). |
| Sound | Yamaha YM2149F Programmable Sound Generator (PSG). Three square-wave tone channels plus one noise channel. 4-bit per-channel volume control with hardware envelope generator. |
| Floppy Controller | Western Digital WD1772 (typically WD1772-02-02). Controls internal 3.5″ DS/DD 720 KB drive and optional external drive via 14-pin DIN connector. |
| DMA Controller | Atari custom DMA IC (C025913). Manages data transfer for the floppy controller and ACSI hard disk interface. |
| GLUE | Atari custom GLUE IC (C025915). Address decode, interrupt management, bus arbitration, DMA request handling, and active display timing. |
| MMU | Atari custom MMU IC (C025912). DRAM address multiplexing and refresh, memory mapping, video counter generation. |
| MFP | Motorola MC68901 Multi-Function Peripheral. Provides four timers, eight interrupt inputs, USART for RS-232, and GPIO. |
| Keyboard/Joystick Controller | Hitachi HD6301V1 (or compatible) embedded microcontroller in the keyboard assembly. Handles key scanning, mouse, and joystick input. Communicates with the mainboard via MC6850 ACIA at 7812.5 baud. |
| MIDI Interface | Second MC6850 ACIA dedicated to MIDI IN and MIDI OUT (5-pin DIN connectors), operating at 31.25 kbit/s. |
| Parallel Port | DB-25 female, Centronics-compatible output. |
| Serial Port | DB-25 male, RS-232C via MC68901 USART with SN75188/SN75189 (or MC1488/MC1489) line drivers/receivers. |
| ACSI Port | DB-19 DMA hard disk interface for external hard drives and laser printers (Atari SH204/SH205, Megafile, etc.). |
| Cartridge Slot | 40-contact card-edge connector. Directly mapped into the address space (128 KB ROM window at $FA0000–$FBFFFF). |
| Joystick/Mouse Ports | Two DE-9 male connectors (active low, accent Atari-standard pinout). Port 0 typically used for mouse, Port 1 for joystick. |
| Video Output | 13-pin DIN (analogue RGB, composite sync, monochrome detect). RF modulator on STFM variants (RCA connector). |
| PSU | Internal switched-mode power supply providing +5 V (≈3 A) and +12 V (≈1 A). Various manufacturers including Mitsumi SR97/SR98, Astec ASP34, DVE DSP-508A. |
| Dimensions | Approximately 470 mm × 260 mm × 65 mm (18.5 × 10.2 × 2.6 in). |
| Weight | Approximately 3.6 kg (7.9 lb) without monitor. |
Custom Chip Set
[edit | edit source]The Atari ST uses a set of four custom ASICs alongside standard off-the-shelf components. These custom chips are the most failure-prone components in the system and are no longer manufactured.
| Chip | Part Number | Package | Function |
|---|---|---|---|
| GLUE | C025915-38A | PLCC-84 | System "glue logic." Generates active display timing, address decoding for I/O and ROM, handles interrupt prioritisation, bus error generation, and DMA request arbitration. Directly controls VPA, DTACK, and bus signals. |
| MMU | C025912-38 | PLCC-68 | Memory Management Unit. Generates RAS/CAS signals for DRAM, handles DRAM refresh, produces video DMA addresses for the Shifter, and manages the memory map configuration. |
| Shifter | C025914 | DIP-40 | Video shift register. Reads video data from DRAM (via MMU), serialises it into pixel data for the monitor output, and manages the 512-colour palette (16 palette registers × 9 bits). Directly drives the analogue RGB output. |
| DMA | C025913 | DIP-40 | DMA controller for floppy disk (WD1772) and ACSI hard disk interface. Provides sector-count-based transfers between disk controllers and system RAM. |
TOS Versions
[edit | edit source]The 1040ST shipped with various TOS versions depending on production date and region:
| TOS Version | Date | Notes |
|---|---|---|
| 1.00 | 1985 | Earliest ROM version. Known bugs in desktop and file system. Sometimes called "old TOS." Shipped in six ROMs on early boards. |
| 1.02 | 1987 | Most common version in 1040STF/STFM units. Bug fixes. Also known as "TOS 1.2" in some documentation. Shipped in two or six ROMs depending on board revision. |
| 1.04 | 1989 | "Rainbow TOS." Numerous bug fixes, improved file selector, DOS-compatible formatting. Some older software incompatible. Also fitted to late STFMs and the STacy. |
| 2.06 | 1991 | Available as a user upgrade. Enhanced GEM desktop, 1.44 MB HD floppy support, IDE boot capability, cold-boot memory test. Requires ROM adapter on most ST boards. |
Motherboard Revisions
[edit | edit source]The 1040STF and 1040STFM were produced on several PCB revisions over the production run:
| Board Number | Revisions | Notes |
|---|---|---|
| C070523-001 | Rev B, C, D | Early 1040STF-specific board. 1 MB RAM in sixteen DIP-16 DRAM chips. |
| C070789-001 | Rev C, D, F | Later unified 520/1040 STFM board. Used for both 520STFM (512 KB, eight DRAM chips) and 1040STFM (1 MB, sixteen DRAM chips). Includes RF modulator section on STFM variants. |
| C103225 | Rev 1, 2 | Late-production STFM board. Simplified layout. |
| C103572 | Rev 1 | Final STFM production board revision. |
The board revision is printed on the PCB itself, usually near one edge. This information is needed when ordering replacement capacitors or consulting schematics.
Connectors and Ports
[edit | edit source]The rear panel (left to right on most models) provides:
- Serial port (DB-25 male) — RS-232C modem/terminal connection
- Parallel/Printer port (DB-25 female) — Centronics-compatible
- ACSI/DMA port (DB-19) — Hard disk and laser printer interface
- External floppy port (14-pin DIN) — Second floppy drive
- RF out (RCA, STFM only) — Modulated TV signal (PAL or NTSC depending on region)
- Monitor port (13-pin DIN) — Analogue RGB, composite video, and monochrome output
- Power switch
- Reset button
On the left side of the case:
- MIDI IN (5-pin DIN)
- MIDI OUT (5-pin DIN)
- Cartridge slot (40-pin card edge)
Under the keyboard:
- Port 0 (DE-9 male) — Mouse/joystick
- Port 1 (DE-9 male) — Joystick
Software Compatibility
[edit | edit source]The 1040ST ran the same software library as other ST-series computers. Its 1 MB of RAM provided sufficient memory for most contemporary applications. Key software categories included:
- Music production: Steinberg Pro-24 and Cubase, C-Lab Creator/Notator, Dr. T's KCS — the ST's built-in MIDI ports and low-latency MIDI timing (driven by the MC6850 ACIA at a fixed 31.25 kbit/s with minimal jitter) made it the platform of choice for professional MIDI sequencing.
- Desktop publishing: Calamus, PageStream, Publishing Partner
- Word processing: 1st Word Plus, WordPerfect
- Programming: GFA BASIC, Lattice C, Mark Williams C, Turbo C (Pure C)
- Games: Dungeon Master, Starglider, Carrier Command, Xenon, Populous
Production and Sales
[edit | edit source]The Atari ST series sold over 3 million units in Europe, where it was particularly strong in Germany, France, and the United Kingdom.[4] The 1040STF was especially popular for music applications and small-business DTP/CAD work due to its competitive pricing against the Macintosh and Amiga.
The ST line was gradually superseded by the STE series (1989), which added hardware scrolling, a BLiTTER chip, expanded colour palette (4096 colours), and stereo DMA audio. Atari discontinued the entire ST computer range in 1993.
Service and Repair
[edit | edit source]See Also
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