PROMs and EPROMs, specifically 2332/2532/2732
jrr at flippers.com
Sun Oct 25 12:21:09 CDT 2015
On 10/24/2015 5:56 PM, Adrian Graham wrote:
> On 24/10/2015 19:18, "John Robertson" <jrr at flippers.com> wrote:
>> On 10/24/2015 5:43 AM, Adrian Graham wrote:
>>> Hi folks,
>>> PET4032 repair continues with all ROMs, video RAM and dodgy sockets removed
>>> thanks to a hot air gun. Holes cleaned and I have new turned pin sockets for
>>> everything I've removed which I'll be fitting this afternoon.
>>> Since the ROMs came out OK I'm trying to dump them using my Pinmaster48
>>> programmer, being from the 90s it doesn't read 2332/2532 PROMs but it WILL
>>> read a lot of variants of 2732 so I've made an adapter as found thanks to
>>> google and USENET:
>>> 2332 pin 18 to 2732 pin 21 (A11)
>>> 2332 pin 20 to 2732 pin 18 (Chip enable/Power Down)
>>> 2332 pin 21 to 2732 pins 20 and 24 via diodes with banding at the 2332 end
>>> (2332 Vpp)
>>> Wiring checks out and the diodes are aligned correctly so pins 20 and 24
>>> don't interfere with each other, however the pinmaster continually gives me
>>> "continuity error on pin 20"
>>> Have I goofed somewhere?
>> You just tie pin 21 of the 2332 to Vcc (+5) - Pin 24 of the 2732 - to read.
>> There are only two modifications needed normally for reading a 2532/2332
>> in a 2732 socket.
>> Pin 21 - Vcc (2732 Pin 24)
>> Pin 18 - A11 (2732 Pin 21)
>> If your reader coughs up a /OE error then use diodes:
>> Pin 20 - 2 Diodes, one to 2732 pin 20, the other to 2732 pin 18. Banded
>> end to these pins, and you will also need a pullup resistor on the
>> 2532/2332 socket pin 20 so /CE (2332/2532) goes high when not selected.
>> 2K2 would do fine. Anything from your junk box between 1K and 4K7 should
>> work though.
>> I don't think you will need the diodes though.
>> John :-#)#
> 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.
Oh, and here is what someone did in 2011 to read 2332s:
More information about the cctalk