Modifying microcode

Henk Gooijen henk.gooijen at
Wed May 30 11:53:32 CDT 2018

Van: Paul Koning via cctalk<mailto:cctalk at>
Verzonden: woensdag 30 mei 2018 18:49
Aan: Camiel Vanderhoeven<mailto:camiel.vanderhoeven at>; General Discussion: On-Topic and Off-Topic Posts<mailto:cctalk at>
Onderwerp: Re: Modifying microcode

> On May 30, 2018, at 11:11 AM, Camiel Vanderhoeven via cctalk <cctalk at> wrote:
> Depending on your definition of small, the MicroVAX 1, and the VAX 8000 series (not that small). In both cases though, the ROM chips are a custom DEC design.

Didn't the 780 get its microcode loaded by the console LSI-11?  And the 730 used bit slice processors (AMD 2901) as I recall, so that had to have its microcode external.


I always thought (…) that the TU58 cassette “in” the front of the VAX-11/730
contained the microcode. For ease, that cartridge was kept in the drive so
that it is available at boot time. Causing a lot of “D”shaped rubber rollers …
Henk, PA8PDP

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