Re: Strange 8255 behavior

From: André Fachat <afachat_at_gmx.de>
Date: Tue, 12 Jun 2018 19:36:36 +0200
Message-ID: <163f51220a0.27e0.b4d1f2b66006003a6acd9b1a7b71c3b1@gmx.de>
Am 12. Juni 2018 5:05:42 PM schrieb Mia Magnusson <mia@plea.se>:

> Den Sun, 10 Jun 2018 14:33:41 +0200 skrev Gerrit Heitsch
> <gerrit@laosinh.s.bawue.de>:
>> On 06/10/2018 01:59 PM, Michał Pleban
> 6821's are even cheaper. Not sure if they would fit, but worth
> investigating.
>
> Btw it could also be made using simple 74xx logic. Two 8-bit latches
> with output enable could each latch written data from one CPU and gate
> the outputs on read by the other CPU. Add the few extra parts needed to
> handshake e.t.c. (maybe a 74**74 dual d-flip-flop could act as a kind
> of interrupt controller, each half in each direction).

Wow that reminds me..... http://www.6502.org/users/andre/csa/copro/index.html
Shared control port with optmistic locking :-)

André
Received on 2018-06-12 20:03:35

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