Date   : Sat, 04 Dec 2004 12:49:02 +0100
From   : Carsten Brasholt <carsten@...>
Subject: Re: Eprom programming problem

Hi There,

I use 27c128's with great success on my beeb... I program them with my 
HCR Electronics EPROM programmer for the Beeb. This programmer supports 
both programming voltages (21V and 12,5V). (CTRL-V changes programming 
voltage, when you have selected 27128 from the menu)

I have tried to program a 27C128 with the wrong voltage (21V), and it 
didn't work (of course). But I could re-program it with the correct 
voltage (12,5V) without any problems, so apparently it didn't blow up.

It might be the HCR programmer, that saved me, as it's fairly advanced. 
But I really don't know about that.

Cheers,
Carsten

Sprow skrev:
> In article <000901c4d978$b38ad6a0$7aeb07c3@...>,
>    John & Helen Simpson <john@...> wrote:
> 
>>Hi there,
>>
>>I have been trying to program an Eprom using Angus Duggan's design for
>>an Eprom programmer (as seen on 8bs and on Angus' own site). Basically
>>my problem is that the Eprom programmer runs OK, but the resultant Eprom
>>is not recognised by the BBC.
>>
>>I think I have worked out what the problem is - I have used a CMOS
>>27C128 whereas the instructions for the programmer seem to imply that
>>you have to use a plain 27128. 
> 
> 
> Reasonable. I encounter 3 types usually
>  27128 - NMOS, 21V for Vpp
>  27128A - NMOS, 12.5V for Vpp
>  27C128 - CMOS, far too weedy to drive the bus
> 
> <blantent ad>
> I have both 27128/27128A available, contact me off list if you're after one
> type specifically
> </blatent ad>
> 
> I use a "Multiprom" programmer with the beeb, which works with both Vpp
> levels, along with some home brewed software created by reverse engineering
> the circuit one dull summer holiday,
> Sprow.
>