Modifying microcode

[Bill Gunshannon]

On 06/02/2018 02:45 PM, Warner Losh via cctalk wrote:

On Sat, Jun 2, 2018 at 12:43 PM, Tony Duell via cctalk <
cctalk at classiccmp.org<mailto:cctalk at classiccmp.org>> wrote:



On Sat, Jun 2, 2018 at 7:37 PM, Alan Frisbie <Flash688 at flying-disk.com><mailto:Flash688 at flying-disk.com>
wrote:


Tony Duell <ard.p850ug1 at gmail.com><mailto:ard.p850ug1 at gmail.com> wrote:



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).



I'm pretty sure that I have a complete set of 11/730 TU58 tapes in
my storage unit.   I might even have some brand new tapes.   If I
can find them, I would be happy to send them to you.   They have
been sitting in storage for probably 20 years, so there are no
guarantee that they are readable.



Thanks... I will certanly give them a go. I am pretty sure the problem
I am having is the tape, I get a low (and varying) amplitude signal at
the output of the read amplifier, it varies with different tapes, and it's
much the same both on the drive in the 11/730 and a standalone
TU58 I have.




Given the vagaries of tape, I'm surprised nobody has made a simple TU58
emulator that can feed the proper microcode bits to the 11/730...

Then again, maybe there's no market for that.



There are TU58 emulators:

https://www.torok.info/computing/pdp11/tu58/

https://www.ak6dn.com/PDP-11/TU58/tu58em/

retrocmp.com/tools/tu58fs

bill