Modifying microcode

Guy Sotomayor Jr ggs at
Wed May 30 12:33:20 CDT 2018

> On May 30, 2018, at 6:51 AM, Noel Chiappa via cctalk <cctalk at> wrote:
>> From: Kyle Owen
>> I do have an 11/45, though... so with this modification, I suppose one
>> could have some fun:
> That's for the -11/40 - very different machine, one couldn't use the same
> technique on the /45; the /40 is prepared to accept additional ucode on
> additional CPU boards, that's how the EIA works:
> And it's custom boards, the design for which is no longer extant (pity, as
> I'd love to play with one myself).
> Finally, I have this vague memory that they had to put a few minor mods on
> some of the existing CPU boards (details also lost), although my memory may
> be misleading me on that.

I’m *very* familiar with the 11/40E as all of our 11/40’s at CMU had been “upgraded”
to 11/40Es (including all of the ones on C.MMP).

I recall the updated micro-code board but I can’t recall if the main CPU boards needed
any mods.  I’ll look over the CMU docs again and see if what might be required.

Did a little bit of micro-programming on the 11/40E but quickly found it was better to
concentrate on efficient algorithms.  ;-)  But to speed up kcalls in Hydra there was at
one point a lot of custom micro-code on the 11/40Es on C.MMP.

TTFN - Guy

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