27 May
2024
27 May
'24
7:17 a.m.
On 2024-05-27 09:54, CAREY SCHUG via cctalk wrote:
Just curioius, as a much less techy person, are there
sets of eproms that are compatible for reading, but just require a different programming
regimen? Could the OP have used a different eprom that is easier to program?
If not, is the limitation pinout, so a header swapping pins could let a different eprom
be used?
<pre>--Carey</pre>
Yes, there are EPROMs, EEPROMS, and PROMs of different technologies that
are pin-compatible. But you have to be careful about access times! When
programmed, they may appear to read the same on the programmer, but
access times may be different. For example on the DEC MXV11 board you
can mount both bipolar and E-PROMs, but the access times are wildly
different. I had a client that brought a board to me that would not run
a standard bootstrap after he copied it from purchased PROMs.. The
problem was that when you bought the boot ROMs from DEC, they were
bipolar (82S series I think). He used EPROMS with many times slower
access speed. The problem was that the PROMs were being read at bus
speed and the data was being presented to the bus way after the CPU had
tried to read it!
cheers,
Nigel
--
Nigel Johnson, MSc., MIEEE, MCSE VE3ID/G4AJQ/VA3MCU
Amateur Radio, the origin of the open-source concept!
Skype: TILBURY2591