Here's the dump of my unknown UD3 (reading with a diode on Vcc gives the same image). The label says S.TOOL (the L in the picture was missing), here're some interesting strings from the dump that I'm sure you would found too: (C) 1981 PDATA OK SUPER*TOOL (049) 613333 The last one is an old italian telephone number from the city of Padova, so it seems that this ROM image was made there by a company called PDATA. I don't remember such a name, but also it passed quite some time. I'll dig out some italian computer magazines of that era, maybe there's a reference on them or some advertisement. Google search didn't give any useful result (maybe I'm not asking the correct question). Someone with a 2001-32 can probably burn a 2532 and try it, my own one needs some months of work to be ready more likely. Frank On Mon, Oct 31, 2016 at 6:04 PM, Gerrit Heitsch <gerrit@laosinh.s.bawue.de> wrote: > On 10/30/2016 10:45 PM, Francesco Messineo wrote: >> >> On Sun, Oct 30, 2016 at 9:15 PM, Gerrit Heitsch >> <gerrit@laosinh.s.bawue.de> wrote: >>> >>> On 10/30/2016 07:28 PM, Francesco Messineo wrote: >>>> >>>> >>>> On Sun, Oct 30, 2016 at 7:23 PM, Gerrit Heitsch >>>> <gerrit@laosinh.s.bawue.de> 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. > > > Gerrit > > > > Message was sent through the cbm-hackers mailing list Message was sent through the cbm-hackers mailing list
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