Reviving a VAX-11/750

Mark J. Blair nf6x at
Mon Jun 15 13:16:31 CDT 2015

> On Jun 15, 2015, at 11:06 , Mattis Lind <mattislind at> wrote:
> Well. I am probably working on to much simultaneously.

I am very guilty of that, too! :)

> Then I compiled your fork of tu58em on github. And it worked perfect. I
> didn't need to use the special vax mode that you have implemented though.
> Maýbe it is required only by 11/730?

You could probably use Don's original tu58em, then. The 730 appears to have one 20ms timeout in a critical part of the drive initialization routine (which is entered repeatedly in normal operation, not just at power-up), and stock tu58em has a delay in that spot that is problematic. Maybe the 750 console code either lacks the timeout check or has a longer timeout period?

> The bad thing with the 11/750 is that is has so many socketed TTL gate
> array chips. Sockets are bad. And gate arrays are bad. In that sense I
> think the 11/730 is better since it is AFAIK based on mostly standard off
> the shelf chips.

Mostly, if I'm not mistaken (I haven't gotten too deeply involved with the PCBs yet). There are a number of PROMs.

Mark J. Blair, NF6X <nf6x at>

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