Modifying microcode

[Tony Duell]

On Fri, Jun 1, 2018 at 6:08 PM, Robert Armstrong via cctalk
<cctalk at classiccmp.org> wrote:
>>Eric Smith <spacewar at gmail.com> wrote:
>
>>The control stores of the 11/785, 8600, and 8650 were entirely WCS.
>>
>>All other VAXen had (relatively) large ROM control store and tiny WCS or
>>patch store.
>
>   You forgot the 11/730 and 725.  The KA730 used 2901 bit slicers and the
> control store was entirely in RAM.  After power on it was a paperweight

Indeed. I think others mentioned that processor too.. For some reason the
control store was built from 16K DRAMs, and the CPU has to wait while
they are refreshed every few milliseconds.

> until the 8085 CFE loaded the microcode.

Loaded from a TU58 cartridge, which is the main reason my 11/730 is not
running at the moment. The hardware is fine, I've rebuilt the drive rollers,
but as yet don't have a readable tape (not even blank, to write the
microcode onto).

Incidentally, did DEC ever release any details (flowcharts, source listings,
etc) of the 11/730 microcode? And what about the control PROMs for the
memory system. The technical manual implies there was a listing of those,
but I've never found it.

-tony