"The Business Line of Atari ST Computers"

Atari Mega ST and Hard Disk

Released in 1986, the Atari Mega ST is a 16-bit business computer widely used in the late 80s for desktop publishing and CAD applications. The Mega ST computers could be easily combined with Atari's laser printers to offer a low-cost DTP package.

  • The Mega ST was initially sold for $1,199 ($3,055 in today's money)
  • The Mega ST line sold about 280,000 units


The Mega ST line includes the MEGA 1, MEGA 2, and MEGA 4 models offering respectively 1,2 or 4 MB of RAM on board. The Mega ST was widely used in Germany.

  • MC 68000 CPU running at 8.0 MHz
  • TOS 1.02/1.04 (check below for more info) and a mouse-driven GEM
  • 1, 2, or 4 MB of RAM
  • 16 colors on screen / 512 colors palette
  • A custom blitter coprocessor was built in some Mega models
  • Three-voice sound synthesis Yamaha sound chip
  • 3.5-inch 720 KB disk drive
  • It came with a high-quality detached mechanical keyboard and a mouse


Operating System

Atari Mega 2 and SC1224 color monior from collection....The Atari ST used a bitmapped color GUI before any other computer. The Mega ST line included two versions of TOS:

1.02 (MEGA TOS)

  • ROM date: 22 April 1987 (192 KB)
  • supports Blitter co-processor
  • supports real-time clock


  • ROM date: 6 April 1989 (192 KB)
  • File selector improved and bug fixes
  • MS-DOS-compatible disk formatting


Colors & Graphic Modes

The ST line supports monochrome, color, and high-resolution monitors and offers a color palette of 512 colors.

  • 320 × 200, with 16 out of 512 colors
  • 640 × 200, with 4 out of 512 colors
  • 640 × 400, with 2 colors
  • The Mega ST line has a PLCC socket for the BLiTTER chip (a bitter chip was included in some Mega models)


Sound Capabilities

The Atari ST line uses the Yamaha "Programmable Sound Generator" chip. The sound performance was significantly upgraded in the later STE models.

  • Yamaha YM2149F PSG sound chip
  • Three-voice sound synthesis
  • Mono sound (stereo only in STE, TT, and Falcon models)
  • MIDI ports built-in


I/O Ports

  • 2 DE-9 male mouse/joystick ports
  • Monitor port (13-pin DIN)
  • DB25 male RS-232c serial port
  • DB25 female Centronics printer port
  • ACSI (similar to SCSI) DMA port (19-pin D-sub)
  • External Floppy Drive Port (14-pin DIN)
  • 2 MIDI ports (5-pin DIN)
  • ST cartridge port (for 128 KB ROM cartridges)
  • Real-time clock



The Atari ST can be connected to TVs, RGB monitors, 15-kHz VGA monitors, or even modern HDMI monitors with the right video upscaling hardware. Note, that the STM/STFM models have a built-in TV modulator, but the output quality is not great.

  • Atari original monitors (mono and color monitors)
  • TVs via SCART cable (RGB to SCART)
  • 15 kHz VGA monitors with an adapter
  • Modern VGA/HDMI monitors via video upscaling hardware


Expansions & Upgrades

  • TOS upgrade
  • Up to 4 MB of RAM
  • Internal expansion connector
  • Gotek drive (internal/exetrnal)
  • External hard disk based on SD cards (ACSI2STM, UltraSatan, and ACSI2STM)
  • 1.44 MB Floppy Disk (requires board)
  • VGA monitor (mono) via adapter


  • PC Dito (emulating MS-DOS via software)
  • PC-Speed (NEC V30)
  • AT-Spee (Intel 80286)
  • ATonce-386SX (Intel 80386SX)
  • Spectre GCR (emulates the Apple Macintosh)


Related Models: Mega STE Model

Mega STE

The Mega STEThe Mega STE is the last STE machine. The computer offered a faster CPU, improved sound capabilities, and better features than the classic Mega ST line.

  • The Mega STE used the Atari TT case
  • The CPU was the MC68000 running at 16 MHz, switchable to 8 MHz for compatibility
  • It was shipped with the improved TOS 2.00.
  • Dual-bus design (16-bit external, 32-bit internal)
  • Built-in 1.44 MB 3.5-inch floppy disk drive
  • VME expansion slot
  • Network port
  • Supports the Motorola 68881 FPU


Atari Mega ST

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