Re: UD3 ROM on a 3032

From: Clockmeister <>
Date: Mon, 31 Oct 2016 05:46:58 +0800
Message-ID: <>
On 31/10/2016 2:23 AM, Gerrit Heitsch wrote:
> On 10/30/2016 06:59 PM, Francesco Messineo wrote:
>> On Sun, Oct 30, 2016 at 6:50 PM, Gerrit Heitsch
>> <> wrote:
>>> On 10/30/2016 06:20 PM, Francesco Messineo wrote:
>>>> Hi all,
>>>> I started working on my 3032 (2001-32), it will be a long project,
>>>> since it's mostly a pile of dirt and rust (I've found it in this state
>>>> 15 years ago, in a side of the street).
>>>> I've seen the UD3 ROM socket populated, here's a picture:
>>>> I'll be reading the EPROM in the next days, does someone have an idea
>>>> about what might that be anyway?
>>> When dumping the EPROM, please dump it twice, once normal and once 
>>> with a
>>> 1N4148 between Vcc of the EPROM and Vcc. Then compare the 2 dumps. 
>>> If they
>>> are the same, you can consider it a successful dump. If not, the 
>>> dump taken
>>> with the 1N4148 might be correct.
>> I can tell my programmer to use a specific Vcc, I have to see what are
>> the limits since I've never played too much with it in the past.
>> Are you suggesting to use 5V and 4.3V or 6V and 5.3V?
> 5V and 4.3V. If an EPROM starts to lose data, it helps to lower Vcc. 
> Why becomes obvious once you understand how and EPROM cell works.

Makes sense if you think about it but it hadn't occurred to me either to 
lower Vcc to read a flakey EPROM.
  Thanks for the hint.

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Received on 2016-10-30 22:00:22

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