Atari ST Computers

Operating System

  • TOS - The Operating System
  • GEM - Graphical Environment Manager
  • boot disk
    • to make an autoboot disk put the program in a folder named “AUTO”, when the floppy boots it will skip the GEM environment and go straight from TOS to the executable, this is the default for most games and demos


Models These are the main models for the US. There are additional models for Europe. There are also some crazy/hard to find/prototype models floating around.

ModelRelease YearDetails
520ST1985 the first ST model, includes 512KB of RAM; uses an external power supply and requires an external floppy drive
520STM1985same as the above but with a built-in RF modulator for connection to an analog TV set
520STFM1986a built-in floppy drive, RF modulator, and power supply
520ST+1986a 520ST but with 1 MB of RAM
1040STF1986 a 520ST with a built-in DSDD disk drive and 1 MB of RAM. The 1040STF only has a monitor output with no RF out.
1040STFM1986 same as above but with a built-in RF modulator
Mega ST1988Redesigned motherboard. Comes with 2 or 4 MB of RAM. Includes a real-time clock and an internal connector for expansion. Most models also include the BLiTTER graphics chip first introduced with the STE range.
520STE and 1040STE1989Same as 520STFM/1040STFM, but includes the BLiTTER graphics chip and enhanced sound. The sound chip has two extra channels which can be used for digitized audio. The color palette is extended to 4096 colors. You'll pay a premium price for these models even though the upgrades were rarely implemented.
Mega STE 1991Same hardware as the 1040STE, but with a 16 MHz CPU and using the same case as the Atari TT desktop computer.


Reset reset buttonna
MIDI out5 pin DINindustry
MIDI in5 pin DINindustry
PrinterCentronics printer port, DB25industry
SerialRS-232C Serial Port, DB25industry
TelevisionRF out, usually channel 2 or 3, RCA type port, only on the STs that have an M in the nameindustry
Joystick(2) DE9, compatible with C64, Atari 2600, Amigameh
Cartridge40 pin on a double edge connectorST
Floppy14 pin floppy portST
Hard DriveASCI (SCSI-like)DMA Port, 19 pin D-Sub, for hard drives and other high speed peripheralsST
Monitor13 pin DIN, 320×200 with 16 out of 512 colors, or 640×200 with 4 out of 512 colors, or 640×400 monochromeST
Power connectorpin DINST

520 ST


  • the best models to get
    1. 520 STE - includes BLiTTER chip, the FDD, RF modulator, and internal power supply
    2. 520 STFM - includes the FDD, RF modulator and internal power supply
  • 68000 based CPU, 512 MB, 8Mhz
  • to make your life easier, look for the 'newer' models that have the power supply built into the chassis
  • 520 Power supply

1040 ST


  • the best models to get
    1. 1040 STE - includes BLiTTER chip, the FDD, and RF modulator
    2. 1040 STFM - includes the FDD and RF modulator and internal power supply
  • 68000 based CPU, 1024 MB,


    • a project to add an external SD card via the HDD port
    • uses a STM32F103C8T6 board
    • faster and cheaper than a Satan /UltraSatan
    • it appears to need a high level of TOS, like v1.04 or better (?)
    • you may need a tool like this - 5v CH340G Serial Converter USB 2.0 To TTL 6PIN Module for PRO mini K9
  • Gotek floppy drive replacement
Last modified: le 2021/08/11 18:38