Atari 520ST+

The Atari 520ST+ was a one-megabyte version of the original short-case 520ST. Introduced in late 1985, it retained the external power supply and floppy drive while doubling the standard memory, giving larger applications and the GEM desktop more room to work.

The model was particularly visible in parts of Europe and served as an early higher-memory ST before the integrated 1040STF arrived. Apart from its fully populated RAM, it closely followed the original 520ST architecture and offered the same graphics, sound and MIDI capabilities.

Notable Features

• Doubled the original 520ST’s memory to 1MB while retaining the compact short-case design.
• Used an external power supply and external floppy drive.

Historical Significance

• Introduced in October 1985 as an early higher-memory ST configuration.
• Bridged the gap between the original 520ST and the integrated 1MB 1040STF.

Collector’s Notes

• The plus sign is part of the model name and appears on genuine case badges.
• Because it resembles a normal 520ST, internal inspection can help distinguish an original 520ST+ from a later memory upgrade.

Specifications

Technical Information
Name	Atari 520ST+
Manufacturer	Atari
Launched	Sunday, December 1, 1985
Discontinued	1988
Country	United States
CPU	Motorola MC68000 at 8 MHz
Units Sold
Operating System	Atari TOS with GEM desktop
I/O	MIDI In/Out, RS-232 serial, Centronics parallel, ACSI hard-disk, cartridge, floppy, monitor and two joystick/mouse ports
Keyboard	Integrated 95-key keyboard with numeric keypad and function keys
Storage	External 3.5-inch floppy drive; ACSI hard-disk support
Sound	Yamaha YM2149 three-channel programmable sound generator
Colour Palette	512 colours
Display	320x200 in 16 colours, 640x200 in 4 colours, or 640x400 monochrome
ROM	192KB TOS ROM
RAM	1MB
CPU Speed	8 MHz