Atari SH205 Documentation

Documentation for the Atari SH205 hard disk drive, also sold as the Megafile 20. Atari's Megafile owner's manual, which covers the utilities for the SH drives, is described on Atari Megafile Documentation.

SH205 controller schematic

Sheet 1 of 2 of Atari (Japan) Corporation's Schematic Diagram (SH205), drawing C100171, size D, drawn by S. Yamada on 5 March 1987, with "next assembly" CA200029. The revision block starts with a preliminary release, followed by later revisions. The notes say capacitors are in microfarads and resistors in ohms, 5 %, ¼ W, unless marked otherwise.

The sheet shows the whole logic of the combined host adapter and disk controller: the 8085 processor (U3), its 64K ROM, the 2116 2K × 8 static RAM (U25), the Adaptec AIC-300 (U24) and AIC-010 (U33), the AIC-250 data separator (U29) with its 10 MHz crystal, and the TTL glue between them and the DMA bus.

What this document does not contain

• Sheet 2 of the drawing, which the scan does not include.
• A parts list, the power supply or the drive mechanism.
• The board number. Some later Megafile 30 units contain a board marked "SH205 C100169 REV.5"; see Atari Megafile 30.

Pages that cite this document

• Atari SH205: controller hardware
• Atari SH204: comparison of the controller arrangements

Download: Atari SH205 Schematic C100171 sheet 1.pdf

Documents not hosted here

The Atari Document Archive (dev-docs.org) lists a second, larger scan of the same schematic, a Dutch Megafile 20 Owner's Manual (C300120-006, C300296-001, Rev. A, 1987) and a Dutch "HD Technical Info" pack covering the SH204, SH205 and Megafiles. Searches of the Internet Archive by title found none of them.