Adaptec 154x Tuning for SCO Unix

[neese at adaptex.UUCP]

>/* ---------- "Adaptec 154x Tuning for SCO Unix" ---------- */
>A recent thread here has discussed tuning some parameters in the Adaptec
>154x driver in 386/ix.  Is there an equivalent set of (administrator
>accessible) parameters in SCO Unix?
>
>I've tried enabling synchronous negotiation and increasing the DMA
>transfer speed via the on-board jumpers.  Neither showed any significant
>change in my simple benchmark (aside from an I/O error when DMA was set
>to 8 MB/s).
>
>>STUFF DELETED
>
>I interpret these similar results to indicate that SCO's driver
>overrides the jumpers in software (as the Adaptec 1542a manual implies
>can be done on p 2-14).  This doesn't explain the I/O error at 8MB/s,
>though...

The SCO driver does override the jumper settings for DMA rate.  I beleive
you need to patch the variable "aha_xfer" to the value you want.  The sync
jumper cannot be overridden by software.
The reason you cannot run at 8MB/sec is the CPU.  The implementation of the
memory addressing will not allow the CPU/bus to run that fast.  Some systems
can run that fast, others cannot.

			Roy Neese
			Adaptec Senior SCSI Applications Engineer
			UUCP @  uunet!swbatl!texbell!
				  {nominil,merch,cpe,mlite}!adaptex!neese