Atari Mega STE
 | |
| Mega STE with monitor, keyboard and mouse | |
| Specifications | |
|---|---|
| Manufacturer | Atari Corporation (Atari Taiwan Manufacturing; EFA Corporation) |
| Type | Desktop computer |
| Released | 1991[1] |
| Discontinued | August 1992 (series production); built to order into 1993[1] |
| Intro price | DM 2,798 (Mega STE 4, September 1991)[1] |
| CPU | Motorola 68000 at 16 MHz or 8 MHz, selectable in software; 16 KB cache |
| Memory | 1, 2 or 4 MB on 30-pin SIMMs, 4 MB maximum; 256 KB ROM |
| Storage | Internal 3.5-inch floppy drive (720 KB; 1.44 MB on later machines); optional internal SCSI hard disk |
| Display | — |
| Sound | Yamaha YM2149 plus 8-bit stereo DMA sound with LMC1992 tone and volume control |
| Graphics | Atari Shifter, 4,096-colour palette; Blitter (not fitted to every machine) |
| FPU / coprocessor | Optional MC68881 or MC68882 |
| Ports / interface | MIDI in and out, Modem 1, Modem 2 and Serial 2 (9-pin D), LAN (8-pin mini-DIN), parallel printer, ACSI/DMA (19-pin D), floppy (14-pin DIN), monitor (13-pin DIN), stereo audio (RCA), ROM cartridge, keyboard; television output on modulator-equipped machines |
| Expansion | One VMEbus Eurocard slot (A24, D16) |
| Power | Internal supply; 95 W maximum[2] |
| Dimensions | 90 × 490 × 290 mm[2] |
| OS / Firmware | TOS 2.05, TOS 2.06 from November 1991 |
| Predecessor | Atari Mega ST |
The Atari Mega STE is the last desktop model of the Atari ST range. It puts the chip set of the STE into the case of the Atari TT030, with a 68000 that runs at 16 MHz with a 16 KB cache, a socket for a floating-point coprocessor, a VMEbus slot, two extra serial ports and a LAN port, and room for an internal hard disk.[1][2] It replaced the Atari Mega ST in 1991.
History
[edit | edit source]Atari presented the Mega STE in London in September 1990 and at the Fall COMDEX in Las Vegas on 12 November 1990. Deliveries were planned for January 1991 but did not begin in earnest until the late summer, from September 1991. From mid-1992 the double-density floppy drive was replaced by a 1.44 MB drive, which needed Atari's Ajax floppy controller in place of the WD1772. An internal Atari memo of 14 August 1992 already describes the machine as discontinued; at the Fall COMDEX that November Atari said it would go on building it to order.[1]
The first machines shipped with TOS 2.05, which runs only on the Mega STE. TOS 2.06, which also runs on the 520STE and 1040STE, followed in November 1991.[1]
Specifications
[edit | edit source]| Item | Specification |
|---|---|
| Processor | 68000 at 16 MHz; optional 68881 or 68882 floating-point coprocessor |
| Memory | 2 or 4 MB RAM, depending on model |
| Display | ST low (320 × 200, 16 colours), ST medium (640 × 200, 4 colours), ST high (640 × 400, 2 colours); palette of 4,096 |
| Interfaces | MIDI in and out; VME-compatible Eurocard slot (A24, D16); monitor; television; parallel; one serial port and two RS-232 modem ports; floppy disk port; LAN; ACSI DMA port; 128 KB ROM cartridge port; mouse/joystick and joystick ports; stereo outputs |
| Sound | 8-bit PCM stereo; three-voice sound generator |
| Keyboard | 95-key keyboard with its own microprocessor |
| Power | Internal supply; 95 W maximum consumption |
| Internal floppy drive | 3.5-inch, 720 KB double-sided |
| Dimensions | 90 × 490 × 290 mm |
atari-computermuseum.de also lists a 1 MB configuration and gives the ROM as 256 KB.[1]
Hardware
[edit | edit source]
The locations below are from Atari's schematic of the main board, revision 2 of April 1990.[3] atari-computermuseum.de gives the board number as C301564.[1]
| Location | Device | Sheet |
|---|---|---|
| U007 | MC68000, 68-pin PLCC | 1 |
| U004, U005 | 8K × 8 SRAM, cache data | 1 |
| U008, U009 | 8K × 8 tag RAM, cache tags | 1 |
| U206, U207 | TOS ROM sockets (1 Mbit EPROM pinout), jumpers W201–W203 | 2 |
| U303, U304 | MC6850 ACIA (MIDI, keyboard) | 3 |
| U305 | Sound generator (drawn as an AY-3-8910) | 3 |
| U306 | MC68901 MFP | 3 |
| U402 | RP5C15 real-time clock | 4 |
| U404 | DMA controller | 4 |
| U405 | WD1772 floppy controller (Ajax on 1.44 MB machines) | 4 |
| U501 | GSTMCU (Glue and memory controller in one chip) | 5 |
| U502 | Shifter | 5 |
| U608 | LMC1992 tone and volume control | 6 |
| U701–U704 | 30-pin SIMM sockets | 7 |
| U801 | System control unit (SCU) | 8 |
| UA04 | Z85C30 serial communications controller | 10 |
| UB01, UB02 | Coprocessor PAL and MC68881 socket (PLCC) | 11 |
Processor, speed and cache
[edit | edit source]The CPU runs at 16 MHz or 8 MHz. The cache is two 8K × 8 SRAMs for data and two 8K × 8 tag RAMs, with PAL logic, on sheet 1 of the schematic.[3] The machine starts at 8 MHz with the cache off; software such as the GENERAL control-panel module or a small AUTO-folder program switches it. The MSTE_CC utilities write $FF to address $FFFF8E21 for 16 MHz with the cache on, $FE for 16 MHz with it off, and $F4 for 8 MHz with it off.[4] Some older programs need 8 MHz; atari-computermuseum.de names every version of Notator before 3.21.[1]
The optional coprocessor is fitted with Atari's kit CA401092-001: the chip goes in socket UB2 and a PAL (C301903-001) in UB1, and jumper W3 is parked on one pin or, on boards without W3, a resistor under the UB1 socket is cut out.[5]
Memory
[edit | edit source]Memory is on 30-pin SIMMs in four sockets, U701 to U704. U701 and U703 share RAS0 and form one bank; U702 and U704 share RAS1 and form the other; each bank has its own high-byte and low-byte CAS lines.[3] Modules of 256 KB or 1 MB are fitted in pairs; a single pair goes in the first and third sockets (U701 and U703) with the other two left empty, giving 512 KB, 1, 2, 2.5 or 4 MB in all. The SIMMs can be reached by removing the hard disk cover, without opening the whole case.[1]
Video, sound and ports
[edit | edit source]The GSTMCU combines the ST's Glue and memory controller. The Shifter gives the ST's three resolutions from a palette of 4,096 colours.[1] DMA sound uses two DAC0802 converters with MF4 filters, and the LMC1992 feeds the left and right RCA outputs (J603, J604) and a mono mix to the monitor socket; the audio section runs from its own 8.2 V regulator (U609, LM78L82) supplied from +12 V.[3] The machine has no extended joystick ports.[1]
The MFP drives the Modem 1 port. The Z85C30 serial controller provides Modem 2, Serial 2 and the LAN port; Serial 2 is disabled while the LAN port is in use. Modem 1, Modem 2 and Serial 2 are 9-pin D male connectors; Serial 2 is mounted on the VME slot cover.[1][6] The LAN port uses RS-422 line drivers (26LS30) and receivers (DS34F86) on an 8-pin mini-DIN.[3] Atari's documents describe it as AppleTalk-compatible, but it was never used as such because of licensing problems.[1] Modulator-equipped machines have a television output and a Lo/Hi channel switch.[6]
VMEbus
[edit | edit source]The VME slot takes one card, which stands on a riser in the case and is fitted from the back after removing the slot cover. It has a 16-bit data bus and a 24-bit address bus.[1][6] The main board brings the bus out on two 50-way connectors, J901 and J902, and the SCU handles VME interrupts.[3]
Storage
[edit | edit source]The internal floppy drive is 720 KB on early machines and 1.44 MB on later ones.[1] Atari's upgrade kit CA401229-001 converts an early machine: the Ajax controller replaces the WD1772 at U405, a new PAL goes in UA2, TOS 2.06 is fitted, and segment 7 of DIP switch S701 is turned on.[7] A 48 MB SCSI hard disk was an option, connected through a host adapter that plugs into the main board.[1]
Real-time clock
[edit | edit source]The clock is a Ricoh RP5C15 (U402) with a 32.768 kHz crystal. The battery plugs into connector J401 and feeds the clock through a diode, D401.[3] The original cell is a Tadiran TL-5242/W, a non-rechargeable 3.6 V lithium cell on a lead with a plug, held in the case with Velcro.[8] See Battery Refurbishment.
Power supply
[edit | edit source]The supply is internal and powers the board through a 12-way connector, J201, which carries +5 V, +12 V, −12 V, −5 V and a Power Good signal.[3] Mega STE supplies documented by exxos are the Phihong PSM-5341, which is also the TT030's supply, and the Phihong PSM-8012-2.[9][10] On a Mega STE, exxos measured 2.9 A on +5 V and 0.11 A on +12 V without a hard disk.[9]
Known faults
[edit | edit source]Supply capacitors, the clock battery, cache faults at 16 MHz, parity SIMMs and the STE video ghosting fault are covered in Atari Mega STE Troubleshooting Guide. The exxos forum's list of recommended fixes names the Mega STE for the video ghosting fix, and includes recapping the supply and avoiding parity SIMMs on all machines.[11]
Documentation
[edit | edit source]- Atari Mega STE Schematic, revision 2 (description)
- Atari MEGA STE Computer Owner's Manual: ports, specifications and pinouts
- Atari MEGA STE 1.44 Megabyte Floppy Drive Installation Manual
- Atari MEGA STE Coprocessor Installation Kit
Related pages
[edit | edit source]- Atari Mega STE General Maintenance
- Atari Mega STE Troubleshooting Guide
- Atari Mega STE Capacitor Replacement Guide
- Atari Mega ST
- Atari 1040STE
- Atari TT030
References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 "Atari Mega STE", atari-computermuseum.de, last edited 24 August 2024, https://www.atari-computermuseum.de/megaste.htm. Secondary source for the history and dates, manufacturers, prices, board number, the 1 MB configuration and 256 KB ROM, TOS versions, the Blitter not being fitted to every machine, the missing extended joystick ports, the LAN licensing, SIMM fitting rules, the VME riser and bus widths, the drive changes and the 48 MB hard disk option.
- ↑ 2.0 2.1 2.2 2.3 Atari Corporation, MEGA STE Computer Owner's Manual, appendix E, "MEGA STE computer specifications", pp. E-1–E-2. Hosted as File:Atari Mega STE Owner's Manual C302016-001 Rev B.pdf.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Atari Corporation, Mega STE Schematic, revision 2, April 1990, eleven sheets. Sheet 1, CPU and cache; sheet 2, clocks, reset, power connector J201, cartridge port and ROM sockets; sheet 3, MFP, ACIAs, MIDI, keyboard, parallel and serial port; sheet 4, real-time clock, DMA and floppy; sheet 5, GSTMCU, Shifter and video; sheet 6, DMA sound; sheet 7, SIMM sockets and DIP switch S701; sheet 8, SCU; sheet 9, VMEbus; sheet 10, SCC serial ports and LAN; sheet 11, coprocessor. Hosted as File:Atari Mega STE Schematic Rev 2.pdf.
- ↑ P. J. Anderson, "MSTE_CC: Atari Mega STE cache control", GitHub; README and source files 16MHZ_CH.S, 16MHZ.S and 8MHZ.S. Community source.
- ↑ Atari Corporation, Atari MEGA STE Coprocessor Installation Kit, C302228-001 Rev A, 1991, pp. 1–3. Hosted as File:Atari Mega STE Coprocessor Installation Kit.pdf.
- ↑ 6.0 6.1 6.2 Atari Corporation, MEGA STE Computer Owner's Manual, chapter 1, "MEGA STe ports and expansion slots", and appendix F, "Connector pinout specifications". Hosted as File:Atari Mega STE Owner's Manual C302016-001 Rev B.pdf.
- ↑ Atari Corporation, Atari MEGA STE 1.44 Megabyte Floppy Drive Installation Manual, C302953-001 Rev A, 1991. Hosted as Atari Mega STE 1.44MB Floppy Drive Installation Manual.
- ↑ François Planque, "How to replace the RTC battery of an Atari Mega STE in 2024", fplanque.com, 14 September 2024. Community source.
- ↑ 9.0 9.1 exxos, "ATARI PSU REPAIR", The LaST Upgrade, part 6, sections "MSTE PSU Phihong PSM-5341" and "MSTE PSU Phihong PSM-8012-2", 2012, updated 2026. Community source.
- ↑ Atari Corporation, Atari TT030 Computer Field Service Manual, C302483-001, August 1991, section 7, parts list (power supply C302074-001, Phihong PSM-5341). Hosted as Atari TT030 Computer Field Service Manual.
- ↑ exxos, "MANDATORY FIXES", exxos's Atari, Amiga & retro forum, 31 January 2019. Community source; items 1, 2 and 8.