🚀 go-pugleaf

When I first put my system together (just this summer--yay) I called around
for the most attractive hard-drive subsystem I could find and wound up with
a promotional deal on a Seagate SCSI drive bundled with their own ST01 SCSI
host adapter.  I wasn't actually looking for SCSI at the time (anything would
have done) but having bought it, the more I thought about it, the more I liked
the idea of using just 1 slot for a standard interface which would let me add
my hard drive and up to six more of all sorts of devices without having to
find a slot for each one and find that they all need to use the same 4 IRQ
lines, etc.

But the realization of this vision seems to be blocked by various problems,
some simply mechanical, others more subtle.  Some may be solved by a different
host adapter--this ST01 is worth about three pizzas and I'm not committed to
keeping it.

1) The ST01 has a 50-pin header on the card, inside, for connection to the
   cable to the internal hard drive.  This is great as long as I can put all
   my SCSI devices inside my system cabinet (fat chance).  Seagate has
   announced a new version of the card which has an internal 50-pin header AND,
   on the rear bracket, the 50-pin connector specified in the SCSI standard;
   the two are just electrically parallel, so one can connect internal and
   external devices.  This seems to me to be simply THE right way to do it.
   Does anyone else make a host adapter like this?

2) An ST01 can't really be a peer on a SCSI bus; it's really designed only to
   initiate transactions with things (drives, mostly) that only respond.  For
   instance, the bit definitions in the control and status registers allow the
   host to drive ATTN and BUSY but not to read them; it can read REQ, C/D,
   I/O, and MSG, but not drive them.  I don't have any application in mind
   where I would need my CPU to be selected by something else, but it might be
   nice to have a host adapter that could allow that.  Someone must make such
   a thing.

3) The manual for my ST01 describes a hardware programming interface: the
   memory-mapping of the ST01 registers, their bit definitions, the function
   of the custom IC, etc.  I'm sure other host adapters are different from a
   programming standpoint.  I have a nightmarish vision of a marketplace full
   of SCSI peripherals, all electrically compatible and using the same SCSI
   protocol, but each one sold with driver software specific to the programming
   details of a particular host adapter--and therefore not compatible at all.
   Is somebody working on a PROGRAMMING standard for host adapters on ISA
   machines--like a defined BIOS interface?  Someone has to be, right?  The
   oversight seems just too gross.

Hmm, I need to sum this up.  What I'm hoping is that someone can steer me to
a manufacturer of SCSI host adapters which a) have physical
connections allowing easy connection of both internal and external devices;
b) are capable of playing all roles in SCSI transactions (selecting/being
selected); c) implement a standard 80x86/ISA/BIOS SCSI programming interface
if such a thing exists or is proposed.  Naturally I also need support for the
BIOS INT 13H fixed disk calls (and a 4-pin connector for the usual AT front-
panel activity light would be nice).  It would be *very* nice if the INT 13H
support included the usual BIOS multitasking hooks, i.e. INT 15H, AH=something,
AL=90 (I think--don't have the book out) before waiting for a disk operation,
and the INT 15H "post" call when the operation completes... I *think* this
could be done by sending the command to the drive, releasing the SCSI bus,
giving the BIOS wait hook, then having the host adapter interrupt when it is
reselected by the drive, and the interrupt handler gives the "post" hook.

*** Any information anyone can offer will be *greatly* appreciated! ***

Also, anybody know how I should look for SCSI peripherals?  Most ads I've seen
for, say, scanners simply assume that you will buy their scanner and their
controller card, and don't even mention what kind of interface connects the
two.  But it seems to me that the whole point of having a SCSI host adapter in
my machine is to be able to go find SCSI peripherals and use them without
buying more controller cards.  Can anyone point me toward SCSI: scanners,
tape drives, CD-ROMs--well, SCSI anythings, for that matter, I'd just like to
know what's out there.

<><><><><><><> Please respond via e-mail; ttardis, apparently because of space
constraints, expires articles quickly, often before I get to read them.  If
anyone asks, I'll summarize to the net.

Thanks!
-Chap Flack  ... uunet ! edsews ! rel ! ttardis ! jcf3703
(p.s. somebody please tell me if my .signature appears below....)
------------------------------------------------------------------------------- chap flack                         ... uunet ! edsews ! rel ! ttardis ! jcf3703

"i look around . . . i feel comparatively healthy."         (steven soderbergh)
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