Date   : Sat, 04 Dec 2004 09:54:56 +0000 (GMT)
From   : Sprow <info@...>
Subject: Re: Eprom programming problem

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.