Modifying microcode

[Lars Brinkhoff]

Rob Doyle wrote:

> Camiel Vanderhoeven wrote:
>> The microcode for the MicroVAX 2 (for which the MICRO2 assembler was
>> used) and the CVAX (which is the CPU in your 3800) is implemented as
>> a mask ROM on the CPU chip itself. No way to change it, and no way
>> you can use MICRO2 to assemble the microcode for the CVAX.
>
> Years ago I was playing the the microcode of the DEC Minnow (PDP-10)
> which was written in MICRO2 - but I don't think I ever found that
> assembler.
>
> Do MICRO2 executables exists?

In ITS, there are two versions of the microcode assembler.  The older
one was used for the KL10, and the newer one for KS10.  I suppose the
KL10 version came from DEC and was originally written in MACRO10, but
then rewritten for MIDAS by ITS hackers.  Then it was extended for the
KS10.

According to the comments above, MICRO2 would have been used for both
PDP-10 and VAX microcode.  So I wonder if it was written in MACRO10 or
MACRO32?