3 Nov
2011
3 Nov
'11
9:41 a.m.
Eric Smith wrote:
John Robertson wrote:
Thanks, I hadn't considered minimum clock speed as a factor. I'll read
the data sheets deeper and check on that. If you could read them with a
6502 based system then I should be able to wire up an adapter for my
Fluke 9010A's 6502 pod to enable me to do a data dump...
Fortunately I have what appears to be the same code in the two 3851s as
in the redesigned 3870 board so reading those should give me useful code
(perhaps with slight address massaging) to work in the 38P70 test CPU.
Then on to designing a replacement for the 3870 once I have good code!
John :-#)#
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Has anyone tried to read the data from the Mostek
3851
PSU (ROM, I/O) used with the 3850?
I've read them in the past. Must have been around 1992 or so. I used
a single-board computer based on the R6511Q microcontroller
(6502-based), and wired the 3851 bus to GPIO port pins. There was
simple firmware in 6502 assembly language, and it output the contents
in S-record format out a serial port. The firmware generated all of
the control signals for the 3851, including the clock, by
bit-banging. IIRC, there was a minimum clock frequency spec for the
3851, but I didn't have any trouble meeting it. I did NOT try to
ensure that all clock cycles were the same duration, which would have
required cycle-counting various code paths, but the 3851 didn't care.
Alas, I don't have the code any more, but that probably doesn't matter
much since it's unlikely that one could find a 6511Q board.
Regrettably I don't have time to develop another 3851 reader, but I
don't recall there having been anything fundamentally difficult about
it. Reading the 3870 single-chip micro is considerably more tricky.