Re: Article PC-card

From: Ruud Baltissen (
Date: 2001-02-22 15:11:17

Hallo Marko,

First thanks for placing the RTC GIF. Looking the result I noticed that my
old email and URL are mentioned with the "External Kernal Card". Could you
correct that please (or remove it)?

> > IOCHCK is an active (L) signal meant to signal the PC that there is a
> > parity error. On the end this signal triggers the NMI-input of the CPU.
> > so we can use the NMI-input of the expansionport.
> Or ignore the signal.

NO. We develloped HW for an hospital which used this line. SW made sure that
the PC did not see this NMI as a parity error. I don't see why other
devellopers could not have done the same.

> "input can be found"?  Probably you meant "can't".

Absolutely correct.

> But there is such an input: the DMA signal (active low) will stop the CPU.

Yes. But also tristates the address- and databus. And that is something that
does not happen with the PC-bus. And I'm very sure not even wanted.

> You could also use free VIC and SID addresses. The last VIC-IIe
> register is at $d030, isn't it?  You could decode and use
> $d031-$d03f for your own purposes.

Do you mean to say that I can use these addresses without any fear of
buscollision? I read some discussions about this subject about a year (?)
ago, but didn't realise this.

Groetjes, Ruud

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