AHA154x host adapter information wanted

Karl Denninger karl at ddsw1.MCS.COM
Thu Feb 1 10:48:23 AEST 1990


Hello!

We're looking for specific programming information/instructions for the
AHA1542 board, and in particular a way to do a few things which should boost
performance.  We've noticed that ISC 2.0.2 seems to be issuing a hard reset
to the card, and since the adapter's BIOS never gets control after that, 
some performance-limiting factors come into play.   In particular, we've 
found:
	o The "transfer rate" jumpers on the controller appear to do nothing.
	o The "synchronous negotiation" jumper appears to do nothing.

Both of these have major impacts on performance under MSDOS, where the BIOS
on the card gets to read the jumpers and "do things".

We would like to be able to:
	
	o Set the transfer rate of the board.  Our motherboards can handle
	  up to 8Mb without any problems, being limited to 5 is bogus.

	o Enable synch transfers.  They work under MSDOS, and result in a
	  huge speed increase!  Our devices can certainly support this
	  option; again verified with "SCSICNTL" from Roy Neese (thanks Roy!)

We've seen as high as 1,500KB/sec (that's 1.5MB/sec folks!) with some "real"
tests under MSDOS, but only realize about 700KB/sec under ISC.  This is with
a Maxtor 8760S.  Howver, the 4380, a SMALLER drive with a lower data rate, 
gives over 1.1MB/sec of transfer rate under ISC!  I have to believe that 
someone tuned that driver for the lower transfer rate, and some juggling 
would greatly improve things.

Has anyone managed to play around with the board under ISC 2.0.2, and get
any or all of this to work?   There are a number of interesting #defines in
/usr/include/sys/aha1540.h, but many of the options don't even appear to be
used in the driver itself!

Any assistance appreciated; if someone has working code that's even better.
We're not afraid to go poking around in the driver or even writing something
to poke the board, driver level or not! 

The Chantel Driver suite is not a realistic option; besides the cost
problems ($500 per system is a little steep) people I have talked to 
who have it say it's not that fast; the HPDD with some tweaking seems to 
be the way to go.

Thanks in advance -- email replies, I will summarize!

--
Karl Denninger (karl at ddsw1.MCS.COM, <well-connected>!ddsw1!karl)
Public Access Data Line: [+1 708 566-8911], Voice: [+1 708 566-8910]
Macro Computer Solutions, Inc.		"Quality Solutions at a Fair Price"



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