Re: PLA equations for the 1551 drive's cart

Hi,
the equations in the .zip file match those in the .c file found on
zimmers and the ones I converted for cupl (so this is the third
confirmation of those equations). There're two jedec files in the .zip
and one has the input terms swapped for the "topmax" programmers.
However the non swapped jedec file doesn't match the one I've obtained
from CUPL but that may be because the 82S100 is largely under utilized
in this situation and the version of cupl I've used just didn't bother
programming all unused fuses while it seems on the files you provided
the unused fuses are all blown.
Either file should work, but I haven't yet any confirmation on the
real hardware. You may want to upload your .zip file to zimmers.net
ftp so we have more "data points" when doing these kinds of reverse
engineering tasks.
Best regards
Frank IZ8DWF

On Sat, Feb 22, 2025 at 12:02 PM Rob Clarke <crock_at_clarke-family.org.uk> wrote:
>
> I have the JED files for this which I got from Ian Gledhill some years
> back. I had just acquired a TopMAX programmer and some blank 82S100's,
> but never got round to testing them. (Another unfinished project !)
>
> Ian also told me that some of the terms need to be swapped for the
> TopMAX, but never really figured out what that meant. I'll mail you the
> files and if they help, great! Would love to know how you get on.
>
> Rob
>
> On 21/02/2025 11:30, Francesco Messineo wrote:
> > nevermind, I figured out they just used the standard 82S100
> > input/output names so I could get the correct pin numbers for the CUPL
> > source file.
> > I'll post the resulting files once verified.
> >
> > On Fri, Feb 21, 2025 at 10:17 AM Francesco Messineo
> > <francesco.messineo_at_gmail.com> wrote:
> >> Hi all,
> >> I need to program a replacement PLA for a 1551 drive, of course I have
> >> blank ICs. Now, the only equations I've found are these:
> >> https://www.zimmers.net/anonftp/pub/cbm/firmware/drives/new/1551/1551.251641-3.c
> >> Pin numbers are not present and it references a mapping but I haven't
> >> really found that one.
> >> It seems to me the code uses the address and bus bits of a 27512 but
> >> I'm not really sure.
> >> PLS100 ICs can be programmed only once, before I try wasting a lot of
> >> them, does anyone have the equations in form of pin number or pin
> >> names according to the schematic? Or does have a reliable mapping for
> >> that C file to actual 82S100 pin numbers?
> >> Of course i'll post the working jedec file once verified.
> >> Thanks in advance
> >> Frank IZ8DWF
>
>