PC-card - DMA

Date: 2001-05-02 21:53:31

Hallo allemaal,

I had a haircut today. This is one of the few moments I am forced to take a 
rest and to do nothing. I was thinking about the PC-card and I suddenly 
realized that we need two 8237's anyway for the simple reason the 16-bit 
ISA-bus has 7 DREQ/DACK lines. This also solves the problem of 16-bit 
transfers as we can use the second 8237 for this feature like a 286+ does.

Unfortunally I still haven't found any details. I remember that someone 
said that he maybe had the missing page I was looking for. Unfortunally I 
didn't note the name. I hope this person will read this email and will be 
so kind to tell if he found anything at all. 

Some study revealed that an IDE-interface does 16-bit transfers only. AFAIK 
the IDE interface doesn't use DMA-lines. DREQ2/DACK2 are connected but, 
AFAIK, only used by the floppy-drive. But that does not mean one cannot 
initiate a DMA transfer from IDE to memory. Is anybody familiar with this 

Groetjes, Ruud


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