PROMs and EPROMs, specifically 2332/2532/2732
mhs.stein at gmail.com
Sat Oct 24 20:19:54 CDT 2015
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
----- 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
> 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
>>> 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
>> 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
> 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.
> Binary Dinosaurs creator/curator
> Www.binarydinosaurs.co.uk - the UK's biggest
> private home computer
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