Tatu Ylonen's SCSI driver

[A. Lester Buck]

In article <YLO.89Jun19143718 at sauna.HUT.FI>, ylo at sauna.HUT.FI (Tatu Yl|nen) writes:
> 
> > I would like to know whether this code is likely to work with
> > other SCSI adapters rather than the Seagate ST-01 - i.e. the Adaptec SCSI
> > adapter, etc.
> 
> I would consider it very unlikely that it would work with any other
> adapter.  The driver needs intimate information on the i/o ports,
> memory areas and dma channels used by the adapter.  These are likely
> to differ greatly between different adapters.  I would consider it unlikely
> that anyone would clone the ST-01.

Well, the ST-01 is a clone itself.  It is just Seagate's repackaging
of the Future Domain TMC-841, at a somewhat reduced price.

> What I hve heard, the Adaptec adapters use dma.  The driver does not
> support dma, as the ST-01 did not (and I did not have any documentation
> on how to use the dma channels in sysV/386).  I have also heard that
> technical documentation of the Adaptec adapter would be hard to obtain;
> I haven't tried though.  (Using a dma-driven controller would probably
> improve performance by several hundred percent from that obtained
> with the ST-01 (under msdos even it performs quite well, though).

I had no problem getting the technical manual for the 1540/1542 adapter
from Adaptec. It costs $5.00 but must be ordered separately (it doesn't
come with the adapter itself).

You don't quote transfer rates for your driver, but I wouldn't expect
an improvement of such magnitude.  When connected and transferring
asynchronously (Adaptec can also do synch transfers), both adapters
operate at about 1.5 MB/sec.  The ST-01 cannot be doing anything
else (i.e., other computing) but it can have other SCSI devices
disconnected.  The Adaptec could overlap computing.  Remember that
all the stock AT controllers do not use DMA either, so DMA is nice
but not essential.  (Also, the Adaptec can transfer host adapter->memory
at a much higher rate (up to 10 MB/sec) than across the SCSI bus.)

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