Atari 1040ST

Atari 1040ST

A 1040ST with an SC1224 colour monitor and the ST mouse
Specifications
Manufacturer	Atari Corporation
Type	Home computer
Released	March 1986 (1040STF)
Discontinued	1989 (1040STF); December 1992 (1040STFM)
Intro price	US$999 with SM124 monochrome monitor, US$1,199 with SC1224 colour monitor (March 1986)
CPU	Motorola MC68000 at 8 MHz
Memory	1 MB (two banks of sixteen 256 kbit × 1 DRAMs)
Storage	Internal 3.5-inch double-sided floppy drive; external floppy (14-pin DIN) and ACSI hard disk (DB-19) ports
Display	320 × 200 (16 of 512 colours), 640 × 200 (4 of 512), 640 × 400 monochrome
Sound	Yamaha YM2149 programmable sound generator, three channels
ROM	192 KB TOS in six 32K × 8 ROMs
Power	Internal switching supply, +5 V 3 A and +12 V 0.9 A, 2 A fuse
OS / Firmware	TOS 1.00, 1.02 or 1.04 with the GEM desktop
Predecessor	Atari 520ST
Successor	Atari 1040STE

The Atari 1040ST is the 1 MB model of Atari Corporation's ST range, with the floppy drive and the power supply built into the case. Atari's service manual gives its full designation as 1040STF ("floppy") and calls the version with a television modulator the 1040STFM. The two versions are described separately at Atari 1040STF and Atari 1040STFM.

The 1040STF went on sale in March 1986 at US$999 with the SM124 monochrome monitor or US$1,199 with the SC1224 colour monitor. The German Atari museum describes it as the first computer sold with 1 MB of RAM as standard. The 1040STFM stayed in production until December 1992, after the STE had replaced the rest of the range.

History

Development of the ST began in May 1984 under Shiraz Shivji, with the internal codename GHU. Atari planned models with an internal drive and power supply from the start, but launched the first STs with external units because separate devices were quicker to get through US type approval; Atari said this saved six months on the power supply alone. The ST was shown in January 1985 and on sale from June 1985 as the Atari 520ST.

The integrated machines followed in spring 1986: the 520STF with 512 KB and a single-sided drive, and the 1040STF with 1 MB and a double-sided drive. Two larger models, the 2080STF and 4160STF with 2 MB and 4 MB, were announced in September 1986 but not released. The 1040STFM was announced in London on 26 May 1988 and was the last model of the original ST generation. When the STE appeared in August 1989, every model except the 1040STFM was discontinued.

Specifications

Atari 1040ST specifications

Item	Specification
CPU	Motorola MC68000 at 8 MHz, 16-bit external and 32-bit internal data bus
RAM	1 MB (1,048,568 bytes usable) in two banks of 512 KB, each bank sixteen 256 kbit × 1 DRAMs
ROM	192 KB of TOS in six 32K × 8 ROMs. Some early 520STs had two 8K × 8 boot ROMs and loaded TOS from disk.
Video	320 × 200 in 16 colours and 640 × 200 in 4 colours, each from a palette of 512; 640 × 400 monochrome. The screen uses 32 KB of RAM and can sit anywhere in memory.
Sound	Yamaha YM2149 programmable sound generator, three channels
Floppy controller	Western Digital 1772
DMA	Low-speed channel (250–500 kbit/s) for the floppy drive and high-speed channel (up to 8 Mbit/s) for the hard disk port; the DMA controller buffers up to 32 bytes
Interrupts and timers	MC68901 multi-function peripheral (MFP), clocked from a 2.4576 MHz crystal
Keyboard	Intelligent keyboard with its own HD6301 microcontroller, linked to the main board through an MC6850 ACIA; the mouse and joystick ports are read by the keyboard processor
MIDI	Second MC6850 ACIA, 31.25 kbaud current loop, MIDI IN and MIDI OUT (with THRU on the OUT socket)
Power supply	Internal switching supply, +5 V at 3 A and +12 V at 0.9 A, 33.5 W maximum input, 2 A fuse

Custom chips

Four Atari chips carry most of the system logic. Atari describes their functions as follows:

• GLUE decodes addresses and generates chip selects, arbitrates the bus during DMA, prioritises interrupts, asserts bus error on illegal accesses, and generates the display timing (sync, blanking and display enable).
• The memory controller (MMU) converts addresses into RAS and CAS for the DRAM, refreshes it, is programmed at power-up with the amount of RAM fitted, and feeds display data to the Shifter.
• The video Shifter turns display memory into pixels and holds the 16 palette registers. The museum gives its part number as C025914 or C301712.
• The DMA controller moves data between memory and the floppy controller or the hard disk port.

Atari's 1 May 1986 parts list for the 1040STFM gives two 68-pin chip-carrier sockets (U12 and U15), 40-pin sockets at U1 and U31, and three crystals: 2.4576 MHz (Y1), 32.0424 MHz (Y2) and 3.579545 MHz (Y3). The STF's DMA chip is C025913-38, the same part fitted to early STEs.

TOS versions

The German Atari museum gives TOS 1.00 for machines built until 1987, TOS 1.02 for 1987 to 1989, and TOS 1.04 from 1989. The ROM dates are 6 February 1986 for TOS 1.00, 22 April 1987 for TOS 1.02 and 6 April 1989 for TOS 1.04.

Motherboards

The museum lists three board part numbers for the 1040STF (C070523, then C070789, then C103088) and two for the 1040STFM (C070789 and C103225). The 520STF and 520STFM use the same boards with half the RAM fitted. The part number is printed on the board.

Connectors

Atari's manual gives the 1040ST back panel, left to right, as: RS232 (modem), printer, hard disk, floppy disk, television output and channel switch (modulator models only), monitor, power switch, mains input and reset button. The left side has the cartridge slot and the two MIDI sockets, and the right side the floppy drive slot. The parts list gives the connector types:

1040STFM connectors (Atari parts list, 1 May 1986)

Connector	Type	Designator
RS232	DB-25 male	J8
Printer	DB-25 female	J7
Hard disk (ACSI)	DB-19 female	J6
External floppy	14-pin DIN	J5
Monitor	13-pin DIN	J4
MIDI IN and OUT	5-pin DIN	J2, J3

Power supply

The 1040ST has an internal switching supply with +5 V and +12 V outputs only. It has a 2 A fuse and a single adjustment that sets both rails together; Atari's instruction is to set the output within ±5 %, 4.75–5.25 V. Typical load is 2.2 A at +5 V and 160 mA at +12 V, rising to 2.3 A and 340 mA during disk access. The supply has overcurrent protection, so Atari notes that a blown fuse usually means a catastrophic failure such as a shorted primary.

The supply runs from mains and its primary-side capacitors hold a charge after it is unplugged. Discharge them before working on it. The Atari 520ST uses a separate external supply instead, with +5 V, +12 V and −12 V outputs.

Documentation

• Atari 520ST and 1040ST Computer Field Service Manual: Atari's field service manual, part number C026118-002 revision B (3.6), January 1987, with the diagnostic cartridge procedure, disassembly, symptom checklist, the 1040STFM parts list and the schematics.
• Atari ST Engineering Hardware Specification: Atari's hardware specification of 7 January 1986.

Service and repair

• Atari ST General Maintenance
• Atari ST Troubleshooting Guide
• Atari ST Capacitor Replacement Guide
• Floppy Drive Repair

See also

• Atari 520ST
• Atari 1040STF
• Atari 1040STFM
• Atari 1040STE