At the end of December 2023, several disk images of very old versions of Seattle Computer Products 86-DOS unexpectedly turned up. This includes previously unseen releases of 86-DOS version 0.11 and 0.34 (going by the version number in the 86-DOS kernel).
Just how old these releases are is somewhat difficult to establish. Unlike 86-DOS 1.0 from April 1981, the older versions used a different format of FAT directory entries. The old format only used 16 bytes per entry (rather than 32) and had no room to store any timestamps, much like CP/M formats of the era.
The 0.34 disk (8″ of course) has a handwritten label which includes a date, 81/02/20. If the disk was written and the label was made on February 20, 1981, the 86-DOS files on the disk are presumably not newer than late February 1981.
The file INIT.ASM on the 86-DOS 0.34 disk contains the following comment:
; Translated from the Z80 on 12-19-80 and subsequently upgraded to handle ; all of the following controllers. Set switch to one to select.
Assuming the comment is correct, 86-DOS 0.34 must have been released sometime after December 19, 1980 but before late February 1981.
The file MSDOS.ASM released by the Computer History Museum includes revision history that starts with version 0.34, which is dated as December 29, 1980. It is likely that the date refers to the DOS kernel itself and not necessarily when 86-DOS 0.34 was shipped to customers.
The 86-DOS 0.11 disk contains no real clues about its age. The sign-on message says “Copyright 1980 Seattle Computer Products, Inc.” which is not too helpful. An interview with Tim Paterson from 1983 suggests that “QDOS 0.11” was finalized in August 1980. While this is possible, the interview is somewhat questionable because there is no sign of “QDOS” in 86-DOS 0.11; the system clearly identifies itself as “86-DOS version 0.11”.
In any case, August 1980 is at least plausible as a release date of 86-DOS 0.11. If so, it would pre-date the release of the IBM PC (and PC DOS) by a whole year.
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