PROMs and EPROMs, specifically 2332/2532/2732

[Adrian Graham]

On 25/10/2015 17:19, "John Robertson" <jrr at flippers.com> wrote:

>> Hi John and others,
>> 
>> Thanks for that. I removed the diodes and wired 2332 (21) to 2372 (24)
>> leaving the A11 swap in place, the programmer complained about pin 18
>> missing. The adapter in front of me is now wired like this:
>> 
>> 2332 (18) to 2372 (21)
>> 2332 (20) 2x diodes to 2372 18 (band) and 20 (band)
>> 2332 (20) 2k2 resistor to 2332 (24)
>> 2332 (21) to 2372 (24)
>> 
>> Now I get "reverse insertion" hinting I've wired something upside-down which
>> isn't the case. I can read 27256 and 2764's no problem so I'm mounting
>> things the correct way.
>> 
>> Further digging into available eproms that the programmer can read reveals
>> it CAN read 2532s, specifically the MCM2532 which the datasheet tells me has
>> the same pinout as the 2332. I still get "reverse insertion error" so I'm
>> guessing my PROMs are toast.
>> 
>> Cheers,
>> 
> 
> Reverse insertion may just mean you are drawing more current on the /OE
> and /CS than expected.
> 
> How about this - go back to my original suggestion (no diodes) and this
> time add a small resistor to the 2732 pin 18 and Vcc to act as a load.
> Try larger resistors if the reader still complains - and try reading
> with NO 2332 in the reader (all FFs). Once you can trick the reader into
> reading air as highs then try your 2332 again with the working resistor
> values for the unused select.
> 
> Oh, and what reader are you using? Did you check with the manufacturer
> (or archives somewhere - archive.org?) to see if they have a trick for
> reading 2532/2332s?

It's an MQP Pinmaster48, a 90s-era programmer. As it happens tonight I got
round to dumping some other EPROMs I had for someone else and one of them
was an SGS2532 which read fine as an MCM2532 so I know the machine works
with that age of chip. All my CBM ones give the same results so I'm assuming
they're dead. Thinking about it there may be some 2532s at work so I can try
burning a PET tester.

I saw the madrigaldesign adapter on Friday but after re-re-remaking the one
I was working on yesterday it was beginning to look a bit rough around the
edges :)

Cheers,

-- 
Adrian/Witchy
Binary Dinosaurs creator/curator
Www.binarydinosaurs.co.uk - the UK's biggest private home computer
collection?