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Personal computer

Atari 520ST

An 8 MHz 68000 personal computer with 512 KiB RAM, TOS ROM and the SHIFTER display subsystem.

Manufacturer
Atari
Released
June 1985
Region
Worldwide
Record status
provisional
A cream Atari 520ST on a museum shelf: a wide keyboard unit with a numeric pad at the right and the Atari logo and model name printed above it, with a boxed games compilation standing behind.

An Atari 520ST in the Helsinki computer and games console museum. The whole computer is inside the keyboard; the power supply and drive were separate boxes.

MKFI · Public domain (released by its author) · Wikimedia Commons

About this machine

The 520ST has writable main RAM and read-only TOS firmware. Keeping each as a component makes the 512 KiB whole-system figure a transparent sum rather than an unexplained convention.

Configuration

520ST retail configuration

Component Role Count Clock Capacity
Motorola 68000 Main CPU 1 8 MHz Nominal clock —
Atari ST SHIFTER GPU 1 unknown Nominal clock — shared
Atari 520ST RAM System memory 1 — 512 KiB shared
Atari 520ST TOS ROM Read-only TOS ROM. System memory 1 — 192 KiB

Figures for the whole machine

Atari 520ST: system figures

provisional A figure marked provisional is recorded but not accepted: its evidence is unsettled. It may rely on one source, an unconfirmed announcement, or a digit read from a damaged scan. The reason appears under the figure. The catalog shows the figure but never uses it in a multiplier. How records are judged.

Metric Value Evidence Basis Method Source
Clock frequency cpu provisional 8 MHz Reported Vendor-rated Nominal clock Stated by the vendor Atari's service manual states this clock for the microprocessor.
Memory capacity whole-system provisional 524 288 B Reported Vendor-rated Design capacity Stated by the vendor The service manual's introduction gives a smaller addressable span because the reset vectors occupy the first addresses. Its Main Memory section gives the installed RAM capacity recorded here. The separate 192 KiB TOS ROM is firmware, not writable working memory.
Rated power consumption whole-system provisional 36 W Reported Vendor-rated Rated power Stated by the vendor This is the maximum input rating of the 520ST's separate power supply, not a measured operating draw.
2 documented absences
Atari 520ST: system figures: documented absences
Metric Value Evidence Basis Method Source
Clock frequency gpu provisional unknown The reviewed manual gives no separate graphics-clock figure. Not stated Vendor-rated Nominal clock Stated by the vendor The service manual describes the Video Shifter and its timing signals, but does not state a separately named graphics-clock frequency.
Memory bandwidth memory provisional unknown The reviewed manual gives no main-memory transfer-rate figure. Not stated Vendor-rated Theoretical peak Stated by the vendor The service manual describes RAM arbitration and peripheral DMA rates, but does not state a main-memory transfer rate from which bandwidth can be stated.

Figures for its components

1 documented absence
Motorola 68000: documented absences
Metric Value Evidence Basis Method Source
Peak FP32 rate cpu provisional not applicable The 520ST does not fit a 68881 floating-point coprocessor. Not stated Vendor-rated Theoretical peak Stated by the vendor Provisional record for atari-520st-68000:peak-fp32-rate: the cited primary manual is registered, but its page-level transcription and independent review are still pending.
Atari 520ST RAM

provisional A figure marked provisional is recorded but not accepted: its evidence is unsettled. It may rely on one source, an unconfirmed announcement, or a digit read from a damaged scan. The reason appears under the figure. The catalog shows the figure but never uses it in a multiplier. How records are judged.

Metric Value Evidence Basis Method Source
Memory capacity memory provisional 512 KiB Reported Vendor-rated Design capacity Stated by the vendor Atari's service manual attributes this capacity to the 520ST's sixteen RAM chips.
Atari 520ST TOS ROM

provisional A figure marked provisional is recorded but not accepted: its evidence is unsettled. It may rely on one source, an unconfirmed announcement, or a digit read from a damaged scan. The reason appears under the figure. The catalog shows the figure but never uses it in a multiplier. How records are judged.

Metric Value Evidence Basis Method Source
Memory capacity memory provisional 192 KiB Reported Vendor-rated Design capacity Stated by the vendor Atari's service manual states this ROM capacity for the 520ST/1040ST system family.

Sources