[TUHS] UNIX "Machine Layer" Standards

John Cowan cowan at ccil.org
Sat Apr 22 03:58:34 AEST 2023

On Fri, Apr 21, 2023 at 10:37 AM Noel Chiappa <jnc at mercury.lcs.mit.edu>

> A little wrong on that date. Even the PDP-11/20 (the first -11) had a boot
> ROM:

The PDP-8/E, which came out in the same year, had a boot ROM if you were
using DECtape as the system device for OS/8.  The bootstrap for the TD8E
DECtape controller was a full device driver 128 words long, way beyond
human toggle-in capability.  It was put up in addresses 77600-77777, which
meant that you could only have 28 kwords rather than the full 32 kwords of

In principle I suppose you could have toggled in the RIM loader (17 words)
and read in the TD8E bootstrap using either Model 33 or high-speed paper
tape, but I doubt if anyone did that.  RIM format alternated between
addresses and values, with each taking up two characters on the paper tape.
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