Re: UD3 ROM on a 3032

From: Gerrit Heitsch <>
Date: Mon, 31 Oct 2016 18:04:44 +0100
Message-ID: <>
On 10/30/2016 10:45 PM, Francesco Messineo wrote:
> On Sun, Oct 30, 2016 at 9:15 PM, Gerrit Heitsch
> <> wrote:
>> On 10/30/2016 07:28 PM, Francesco Messineo wrote:
>>> On Sun, Oct 30, 2016 at 7:23 PM, Gerrit Heitsch
>>> <> wrote:
>>>> 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.
>>> ok, I'll do that. If it's marginal, then it helps to read at Vcc of 5.5V
>>> or 6V.
>> No, if it's marginal, you need to read it at LOWER Vcc.
> ok I understand, low gate charge makes a better "0" at lower Vcc, isn't it?

Yes... The same reason why you verify the EPROM after programming with a 
higher Vcc (6V or so), to make sure the cells have a large margin when 
used at +5V. Most programmers do that automatically.

Of course, there is a lower limit to how far you can reduce Vcc, but so 
far any EPROM I tried had no problem with a 1N4148 used to steal in the 
range of 0,7V and there were EPROMs where that made the difference.


       Message was sent through the cbm-hackers mailing list
Received on 2016-10-31 18:00:03

Archive generated by hypermail 2.2.0.