Re: General 6809 card for 6502 machines

From: Nils Eilers <nils.eilers_at_gmx.de>
Date: Wed, 18 Oct 2017 14:42:53 +0200
Message-ID: <bcf98016-21a6-b6d8-a402-859e0fe7b7aa@gmx.de>
> I've never found this board at a decent price on ebay...
>
> that's why I was thinking to rebuild one
> I'm actually on a reproduction of the 8032 64k extension

Actually I'm almost done with a SuperPET clone, the PCB layout on a 10 x
10 cm board is near completion.

I'm using a EPM7128 CPLD by Altera (PLCC84 housing), 128 KB Flash, 512
KB RAM, 6551 ACIA and a few TTL chips and the 6809E CPU of course. Its
main purpose is to upgrade a stock 8032 board to a SuperPET board but
some other configurations, such as emulating an 8096 RAM extension
should be possible as well.

Due to its unbeatable simplicity, I've kept the solution of powering the
6502 off when the 6809E is active but offered support for the WDC65C02
as well. The WDC65C02 seems to allow to tristate the address bus and
data lines, so I added a jumper to the board to use this one too instead
of the old NMOS 6502.

If some of you guys would be interested in having a look at my design,
I'd upload the design to my website. As I said, it's almost done, but
maybe good reasons will arise for late time changes.

Nils



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