RE: Article PC-card
Date: 2001-02-26 03:59:46

Hello Ruud,

>but...). I don't see any reason why it should not work for a >360KB floppy,

>for the 1.44 I have my doubts.

A 1.44Mb floppy interface using DMA has been done by a guy in Hungry...

I think the point I was making if that IOCKRDY halts the 80x86 CPU, which is
fine.... but my understanding was that the DMA ops on a PC also use this
line to tri-state out the CPU and allow mem-to-IO transfers. In the PC case
the 8237 does the data interchange. But if you DMA the C64 by connecting it
to this wire, who would control the data on the bus without addition DMA
control functions? If the 6510 remains is to remain in control then this
limits to control to PIO functionality.

I have another question for you though... I've often thought about the
issues of connecting a VGA card for example to a C64 using such a PC card
you describe.  For this though there is both IOR and IOW control needed for
the control registers and MEMR and MEMW for actualing putting data on the
RAM.  How do you know that read/writes to the RAM won't clash with the VGA
controllers accesses?

- Nick


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