82s100 to 27c512 adapter

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82s100 to 27c512 adapter

André Fachat
Hi,

I am in the process of fixing a 8296, and found a dead UE5 PLA - now I wanted to build a 27c521 adapter for it, but the only "standard" adapter seems to be the one by Jens Schönfeld mentioned e.g.
http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/c64/index.html

However, I could not find an explicit schematics or pinout description of this adapter. The only thing reasonable I found was on
http://groups.google.com/group/comp.sys.cbm/msg/e20aa2884becfa16
but is this the correct one?

Can anyone please send/point me to this info? (and/or put that on the CBM archive as well?)

Many thanks,
André

P.S.: I have managed to build a working coprocessor board for my CS/A computer :-) I only wait for Mike to publish it to the web, but he seems pretty busy.


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Re: 82s100 to 27c512 adapter

Andreas Paul
Hello André,
I am using this one:

http://www.vic20.de/html/eprom_pla_8296_und_c64.html

Best regards
Andreas

P.S.: In theory quite fast eproms should be used, but it is strange that
some slower eproms work even better than nominal faster ones.

André Fachat schrieb:

> Hi,
>
> I am in the process of fixing a 8296, and found a dead UE5 PLA - now I wanted to build a 27c521 adapter for it, but the only "standard" adapter seems to be the one by Jens Schönfeld mentioned e.g.
> http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/c64/index.html
>
> However, I could not find an explicit schematics or pinout description of this adapter. The only thing reasonable I found was on
> http://groups.google.com/group/comp.sys.cbm/msg/e20aa2884becfa16
> but is this the correct one?
>
> Can anyone please send/point me to this info? (and/or put that on the CBM archive as well?)
>
> Many thanks,
> André
>
> P.S.: I have managed to build a working coprocessor board for my CS/A computer :-) I only wait for Mike to publish it to the web, but he seems pretty busy.
>
>
>  

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Re: 82s100 to 27c512 adapter

Spiro Trikaliotis
Hello,

* On Mon, Dec 18, 2006 at 01:06:21AM +0100 Andreas Paul wrote:
 
> André Fachat schrieb:

> > However, I could not find an explicit schematics or pinout description of this adapter. The only thing reasonable I found was on
> > http://groups.google.com/group/comp.sys.cbm/msg/e20aa2884becfa16
> > but is this the correct one?

What is "the"? After that posting, there was at least one success report
for it, so it seems to work.

This may not be the optimal layout of the adapter, as I did not have a
look at the physical aspects of such an adapter.

 
> P.S.: In theory quite fast eproms should be used, but it is strange that
> some slower eproms work even better than nominal faster ones.

Faster EPROMs tend to generate more "ripples" while switching, while
lower don't (as they cannot react that fast). This might be the reason
why slower EPROMs are better suited in some cases.

Regards,
   Spiro.

--
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Re: 82s100 to 27c512 adapter

Nicolas Welte
In reply to this post by André Fachat
Hi André,

André Fachat wrote:
> Hi,
>
> I am in the process of fixing a 8296, and found a dead UE5 PLA - now I wanted to build a 27c521 adapter for it, but the only "standard" adapter seems to be the one by Jens Schönfeld mentioned e.g.
> http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/c64/index.html

Did you consider using the GAL replacement instead? For UE5 this is
possible and a much nicer solution than the EPROM fix:

http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/pet/8296/8296ue5cr.zip

I used your equations to build it :)

I can also burn the GAL for you if you can't do it yourself.

Nicolas

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Re: 82s100 to 27c512 adapter

André Fachat
In reply to this post by Spiro Trikaliotis

Hi Spiro,

with "the" I mean if this is the one mentioned to by from Jens Schönfeld as referred to in the CBM archive. I thought it would be a good idea to document this (Jens') adapter if it is referred in the archive.

André

-------- Original-Nachricht --------
Datum: Mon, 18 Dec 2006 08:02:54 +0100
Von: Spiro Trikaliotis <[hidden email]>
An: [hidden email]
Betreff: Re: 82s100 to 27c512 adapter

> of this adapter. The only thing reasonable I found was on
> > > http://groups.google.com/group/comp.sys.cbm/msg/e20aa2884becfa16
> > > but is this the correct one?
>
> What is "the"? After that posting, there was at least one success report
> for it, so it seems to work.

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Re: 82s100 to 27c512 adapter

André Fachat
In reply to this post by Nicolas Welte

Hi Nicolas,

I did not have a look at the GAL solution, as I have two 27C512 around here already :-) Also I have another 8296 board here that has missing UE6 PLA.

Thanks anyway
André

-------- Original-Nachricht --------
Datum: Mon, 18 Dec 2006 09:20:58 +0100
Von: Nicolas Welte <[hidden email]>
An: [hidden email]
Betreff: Re: 82s100 to 27c512 adapter


> Did you consider using the GAL replacement instead? For UE5 this is
> possible and a much nicer solution than the EPROM fix:

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Re: 82s100 to 27c512 adapter

Marko Mäkelä-3
In reply to this post by André Fachat
On Mon, Dec 18, 2006 at 11:26:46AM +0100, "André Fachat" wrote:
> with "the" I mean if this is the one mentioned to by from Jens Schönfeld
> as referred to in the CBM archive. I thought it would be a good idea
> to document this (Jens') adapter if it is referred in the archive.

I wrote a C program to generate EPROM dumps from the logic equations.
You can adapt the pinout in the source code easily by editing the
macros for the signals and the translation for the data lines in
the main program:

http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/c64/pla.c

"This C program contains the logic equations for the 82S100 PLA chip
used in the C64 (906114-1), and converts them to a 64-kilobyte truth
table file. In this second version of the program, the input and output
lines are permuted so that they correspond to the 82S100-to-27512
adapter built by Jens Schönfeld, so that he could read out the PLA with
an EPROM programming device."

FWIW, I wrote a similar C program for permuting address or data lines
in ROM dumps.  It's trivial if you can keep the image in an array.
My 4 MB Flash ROM cartridge for the VIC-20 (sorry, I haven't got around
to completing the file system generator) permutes some lines to gain
easier circuit board layout.

        Marko

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