PROMs and EPROMs, specifically 2332/2532/2732

[Mike Stein]

Probably a silly question, but I assume that if 
you're using a 28-pin socket you are inserting it 
aligned at the end *opposite* pin 1, with pin 
numbers offset by 2 (ie. 2x32 pin1 is 2764/256 pin 
3, etc.)?

m


----- Original Message ----- 
From: "Adrian Graham" 
<witchy at binarydinosaurs.co.uk>
To: <jrr at flippers.com>; "General Discussion: 
On-Topic and Off-Topic Posts" 
<cctalk at classiccmp.org>
Sent: Saturday, October 24, 2015 8:56 PM
Subject: Re: PROMs and EPROMs, specifically 
2332/2532/2732


>
>
>
> 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?
>>>
>>> Cheers,
>>>
>> 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.
>>
>> 2332
>>
>> Pin 21 - Vcc (2732 Pin 24)
>> Pin 18 - A11 (2732 Pin 21)
>>
>> If your reader coughs up a /OE error then use 
>> diodes:
>>
>> 2332
>>
>> 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.
>
> Cheers,
>
> -- 
> Adrian/Witchy
> Binary Dinosaurs creator/curator
> Www.binarydinosaurs.co.uk - the UK's biggest 
> private home computer
> collection?
>
>