PROMs and EPROMs, specifically 2332/2532/2732

John Robertson jrr at
Mon Oct 26 12:09:50 CDT 2015

On 10/25/2015 4:37 PM, Adrian Graham wrote:
> On 25/10/2015 17:19, "John Robertson" <jrr at> 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 - 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,
Hi Adrian,

Perhaps one final test for your 2332s is to do a Diode Test on the pins 
relative to the ground pin (pin 12) and Vcc pin (24). These should sow 
either open or something like 0.6 or higher voltage drop across the pins 
- exchange the probes to check both directions.

If your gates all read OK (check between Vcc and GND as well!), then it 
might be that the brand of 2332 you have simply draws more current than 
your programmer likes. What brand is the PROM? Perhaps it is in one of 
our reference book libraries...

If your 2332s are bad, then have you put out a call to see if anyone 
else has archived them already?

John :-#)#

John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
"Old pinballers never die, they just flip out"

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