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Re: FPGA replacment for the ZX8301 ULA and more

Posted: Fri Apr 05, 2024 5:04 pm
by lliont
It a matter of 3-4mm
I use these pins that are perfect for round pin sockets and are thin enough not to destroy the others unless you insert and remove many times.

5272971692517406008.jpg
if only they where a bit longer from either top or preferably bottom side.

Re: FPGA replacment for the ZX8301 ULA and more

Posted: Fri Apr 05, 2024 5:45 pm
by ones' complement
lliont wrote: Fri Apr 05, 2024 2:48 pm I'll reconsider the expansion port but new pcb from the begining and new tests ... : :cry:
Ah, it was only theoretical question not practical. Your achievement this far has been tremendous 8-)
lliont wrote: Fri Apr 05, 2024 2:48 pmI have to admit that there is a problem with those red tall cpu sockets
They are very flaky, easily splitting into two which makes then the simplest socket to replace (pins can be removed one by one). Turned pin strips (or 2x DIP24) would provide best anchor for board.

Re: FPGA replacment for the ZX8301 ULA and more

Posted: Fri Apr 05, 2024 6:09 pm
by tetroid
lliont wrote: Fri Apr 05, 2024 5:04 pm It a matter of 3-4mm
I use these pins that are perfect for round pin sockets and are thin enough not to destroy the others unless you insert and remove many times.


5272971692517406008.jpg

if only they where a bit longer from either top or preferably bottom side.

Hi.

We can't find the long round connector, but we can use the short connector instead the normal and the normal instead the long.

Re: FPGA replacment for the ZX8301 ULA and more

Posted: Fri Apr 05, 2024 6:17 pm
by lliont
Nice I'll look for the short one, thanks.

Re: FPGA replacment for the ZX8301 ULA and more

Posted: Fri Apr 05, 2024 6:22 pm
by tetroid

Re: FPGA replacment for the ZX8301 ULA and more

Posted: Fri Apr 05, 2024 10:57 pm
by Peter
lliont wrote: Thu Apr 04, 2024 12:15 pmPCEN
Not obvious to me why you'd need that.

Re: FPGA replacment for the ZX8301 ULA and more

Posted: Sat Apr 06, 2024 4:22 pm
by ones' complement
PCEN peripheral chip enable. Surely any ZX8301 replacement will need to provide it for ZX8302 on pre issue 6 QLs (also TXOE).

Re: FPGA replacment for the ZX8301 ULA and more

Posted: Sun Apr 07, 2024 1:27 pm
by Peter
ones' complement wrote: Sat Apr 06, 2024 4:22 pm PCEN peripheral chip enable. Surely any ZX8301 replacement will need to provide it for ZX8302 on pre issue 6 QLs (also TXOE).
Thanks, I forgot and just looked at the issue 6 schematics. Pity an expansion port solution fails just because of that.

Another thought might be whether the ZX8301 needs to be replaced at all, if its video signals (the weak spot) were no longer used. New ones could be accessible at the expansion port. This board is no timing compatible replacement anyway, so going the "GoldCard" way - just with video - could make sense.

Re: FPGA replacment for the ZX8301 ULA and more

Posted: Sun Apr 07, 2024 6:18 pm
by lliont
I'll think about how it could be adapted to use the expansion port when I find some time, I am busy with some other things these days.
Worst case I could simply use few cables to the socket or something.

Re: FPGA replacment for the ZX8301 ULA and more

Posted: Sun Apr 07, 2024 7:07 pm
by Chris_68
Hi

Leon, great work as always.

I haven't all the posts but could it be possible to use your PCB and design an adapter board with the socket for CPU and 8301 routed to a DIN41612, this instead of having to reroute the PCB?