SCP/Microsoft 20HAL uploader

dwight dkelvey at
Sun Sep 27 12:34:59 CDT 2020

This is great work, Rich. It is like looking at dinosaur bones and trying to figure what it was eating.

From: cctalk <cctalk-bounces at> on behalf of Richard Cini via cctalk <cctalk at>
Sent: Sunday, September 27, 2020 7:07 AM
To: Discussion: On-Topic Posts Only <cctech at>
Subject: SCP/Microsoft 20HAL uploader

All –

                I’ve done a quite a bit of work with my Seattle Gazelle, and I just did some work on 86DOS.SYS (not released in source form, as far as I know) and its comparison to PC DOS 1.0 (at the code level, a very high correlation as you can imagine). Partially related to that is a program called “20HAL” which was a code uploader Microsoft used in the late stages to get code from Microsoft in Bellevue to IBM in Boca Raton, FL. I did a little write-up on it here (

                There are some holes in the analysis – I think it’s pretty close, though -- but I’d really like to get some more details on it. Unfortunately, it’s 40-year-old code at this point, and how many people remember how they used a file transfer utility that long ago?

                Anyway, enjoy the read. If anyone sees any corrections that need to be made, let me know. Thanks!



Rich Cini

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