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Reading through early MS-DOS history on the OS/2 Museum site, it mentions how the primary developer on the project for bringing QDOS up on the IBM PC prototype was Robert O’Rear, and that his name is immortalized in the PC DOS 1.0 boot sector.

Is there a story behind this other than a developer's easter egg? Is it just a 'ROR' taking over a few free bytes? As well, how long did this tag live on our PCs before it was removed? Did it make it over to MS-DOS?

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  • 12
    It's pretty hardcore to be an assembler programmer with a name that also forms an acronym for a mnemonic :)
    – Lundin
    Commented Dec 4 at 16:07

1 Answer 1

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Robert O'Rear's name is at offsets 0168h through 0175h of the boot sector. In version 1.10 it was replaced with the company name (see the first reference below for more details).

At least according to Tim Patterson, this was probably never in MS-DOS. In 2013, he wrote the following email:

From: Tim Paterson
To: Len Shustek
Date: Mon, 16 Dec 2013 10:34:17 -0800
Subject: RE: Source code to MS-DOS 1.0

I have found and attached the source code for MS-DOS 1.25 as shipped by Seattle Computer Products. Version 1.25 was the first general release to OEM customers other than IBM so was used by all the first clone manufacturers.

IBM's DOS 1.1 corresponds to MS-DOS 1.24. There is one minor difference between 1.24 and 1.25, as noted in the revision history at the top of MSDOS.ASM.

Of the file attached, only STDDOS.ASM/MSDOS.ASM (DOS main code) and COMMAND.ASM (command processor) would have been used by an OEM other than Seattle Computer. The other files:

IO.ASM - I/O system unique to SCP (equivalent to ibmbio.sys). ASM.ASM & HEX2BIN.ASM - Old 8086 assembler developed by SCP (used to assemble older version of DOS). TRANS.ASM - Z80 to 8086 assembly source code translator developed by SCP.

I also have a 6” stack of printouts of assembly listings for some of these and probably other related programs.

Tim Paterson Paterson Technology http://www.patersontech.com/

So, by (what Patterson saw) as version 1.24, it had already been replaced by the company name, and the first version to go to any OEMs was 1.25.

References

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  • Sorry if I missed this somewhere; but can you elaborate on how the hex dump w/ highlighting was generated for this answer? I really like the highlighting and it looks dead useful for reverse engineering; but I'm not familiar with the tool. (I'm assuming this was done with a hex editor or a disk track/sector editor and not by hand in GIMP).
    – Geo...
    Commented Dec 4 at 17:21
  • 5
    it looks like hand-rolled HTML over fixed-width text. The tagging is clean and minimal
    – scruss
    Commented Dec 5 at 0:50

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