ISA bus throughput
cclist at sydex.com
Thu Feb 2 11:46:47 CST 2006
On 2/2/2006 at 6:44 AM mbbrutman-cctalk at brutman.com wrote:
>Yes, this would be interesting. I had never realized that IDE was a
>superset of ST506. Now I'm thinking of all of the old 8 bit machines I
>could use an IDE hard disk. I've been trying to graft SCSI cards onto
them, but 8
>bit SCSI cards with BIOS aren't exactly common either.
Careful--most recent IDE drives are not capable of 8-bit data transfers.
Commands and status are read and written from 8 bit registers, but the data
transfer part of the operation is 16 bit. There IS an 8-bit transfer
capability defined by the ATA standard, but it was deprecated in ATA-3 and
most drives don't handle it. There may be some old controllers around
that can do the translation, but ATA on 8 bit PC-XT was pretty rare.
However, it'd be easy to prototype up a controller. Alternatively, you
could do much of what you wanted in software--just ignore half the sector
data and read 2 sectors when one was requested. All in all, it'd probably
STILL be faster than the old 5.25 MFM drives.
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