PROMs and EPROMs, specifically 2332/2532/2732

[Mike Stein]

PET ROMs archive here:
http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/pet/index.html


----- Original Message ----- 
From: "John Robertson" <jrr at flippers.com>
To: "General Discussion: On-Topic and Off-Topic 
Posts" <cctalk at classiccmp.org>
Sent: Monday, October 26, 2015 1:09 PM
Subject: Re: PROMs and EPROMs, specifically 
2332/2532/2732


> On 10/25/2015 4:37 PM, Adrian Graham wrote:
>> 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,
>>
> 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)
>                  www.flippers.com
> "Old pinballers never die, they just flip out"
>