LSI-11/2 microcode source

[Heinz Wolter]

"Eric Smith" <eric at brouhaha.com> replied:
Subject: Re: LSI-11/2 microcode source

darn - I was hoping it was simpler! too bad the PLAs can't
be deduced from the native microinstruction set/ISA..

knowing the binary contents of the first MICROM would be
enough for me.. I guess the addresses need only to be sequenced,
data read (with an analyzer) while providing the odd voltages and
multiphase clocks... unless someone out there has the listing ;)

my M7270 contains a control chip 1611-H  21-16890-00 (8015 date),
and CP1621B14 data chip while my
M7264 has a DEC badged ceramic 1611A 21-11549-01 (7717 date)

The AM100 appears to have a1611B. I assume these are diff. mask sets.
What the WD1600 stock set use? The Pascal Microengine?
regards
h 

> Heinz wrote:
> > Alternate anyone have info on reading out the WD PMOS roms?
> 
> Reading the MICROMs wouldn't be that difficult.  But it's not the
> whole story.  The control chip has two metal-mask PLAs ("translation
> arrays") that can cause PC changes even when the current microinstruction
> is not a branch, based on two 8-bit translation registers and various
> other inputs.
> 
> You can't, because the translation arrays are different in the LSI-11,
> Pascal Microengine, and WD-16.  The data path chip of the Pascal
> Microengine and WD-16 are the same, but I'm not 100% certain that it's
> the same as that of the LSI-11.
> 
> Also, the system-level interface of the LSI-11 and Pascal Microengine
> are different.  There are four bus control signals from the MICROMs that
> get decoded for bus control, and they are not used identically in the
> LSI-11, Pascal Microengine, and WD-16.  Even if you swap the control
> chip along with the MICROMs, the Pascal Microengine doesn't know how to
> talk to a Qbus.
> 
> Eric
>