Xref: utzoo comp.periphs:2159 comp.sys.ibm.pc:35860 Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!sharkey!cfctech!rel!ttardis!jcf3703 From: jcf3703@ttardis.UUCP (chap flack) Newsgroups: comp.periphs,comp.sys.ibm.pc Subject: SCSI host adapters for ISA bus: wish list: know any contenders? Keywords: SCSI ISA Winchester CD-ROM scanner BIOS standards ha Message-ID: <2303@ttardis.UUCP> Date: 6 Oct 89 03:46:01 GMT Organization: DynaLogic Engineering Lines: 83 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) ------------------------------------------------------------------------------- brought to you by the kind hospitality of the ttardis public-access people . . . any views expressed here are my own (or were when i wrote them)