liberato@drivax.UUCP (Jimmy Liberato) (07/16/90)
When I install a SOTA 386si (366sx) accelerator into various XT
class machines the ideal hard drive interleave factor (as reported
by Spinrite) suddenly jumps up, generally from about 4 to 7.
Now I know that the wait states involved in accessing slow 8 bit
memory are pretty extreme but why would there be any effect on
the drive and controller? This happens on three unrelated 8088
machines. Is there something I'm missing here? Any comments
are appreciated.
--
Jimmy Liberato liberato%drivax@uunet.uu.net
{uunet|amdahl}!drivax!liberato RFM@psuvm.psu.edu (07/18/90)
SOTA has a BBS -- 1-408-745-0326 -- 8-N-1, FDX. Cal 'em and ask. Bob M., PSU Harrisburg.
del@fnx.UUCP (Dag Erik Lindberg) (07/26/90)
In article <AVPMT6W@drivax.UUCP> liberato%drivax@uunet.uu.net (Jimmy Liberato) writes: >When I install a SOTA 386si (366sx) accelerator into various XT >class machines the ideal hard drive interleave factor (as reported >by Spinrite) suddenly jumps up, generally from about 4 to 7. Typically what happens with these accelerator boards is that they do not do disk I/O or keyboard I/O directly. This is so they will work in a wider variety of machines without compatibility problems. The accelerator typically works by taking over the bus from the 8088 (the 8088 is suspended in a hold state). When keyboard or disk I/O is required, an I/O request is queued up for the 8088 and the bus is released. The 8088 fires up (executing it's side of the driver BIOS for the accelerator board), processes the I/O request, depositing the data and status in predetermined locations, and enters HOLD state again. The accelerator then starts up again, and moves the data into it's own, usually on-board, 32 bit, memory. The additional sector skew you are seeing is a result of this double CPU swapping for every I/O request. This is why accelerator boards work quite well for spreadsheets and other CPU intensive tasks, but offer little, if any, performance boost for things like databases. this CPU swapping. -- del AKA Erik Lindberg uunet!pilchuck!fnx!del Who is John Galt?