Sys V/AT strange floppy problem

[A. Lester Buck]

In article <103727 at sun.Eng.Sun.COM>, plocher%sally at Sun.COM (John Plocher) writes:
>>beginning to suspect something on the mother board, having to do with
>>DMA transfers, or some other feature that uport utilizes, that DOS doesn't.
>I think you hit it on the head here.  Microport uses DMA for the floppy device,
>DOS does not.

DOS *does* use the DMA hardware for the floppy transfers.  Check the
BIOS listings in the Tech Reference manuals.

>One way to test this out is try (under DOS) the fastback install
>program.  It tests the DMA chips under a simulated load and will tell you if
>the DMA controller is bad.  If it is, hope and pray it is socketted on the

I have no direct experience with Fastback, but I have read that it is
only checking that your DMA chip can support two simultaneous DMA
transfers (i.e., two DMA channels active at once).  If the DMA
chips did not support a single DMA transfer, you would not be able
to boot from the floppy.

-- 
A. Lester Buck		...!texbell!moray!siswat!buck