#: 4909 S10/Tandy CoCo
    05-Jul-90  18:25:54
Sb: #4884-#SCSI drives
Fm: Kevin Darling (UG Pres) 76703,4227
To: Bob van der Poel 76510,2203 (X)

Sounds like Scott can fix you up (with answers, also). In the meantime,
simplified: a bus (usually via a cable) with devices hooked to it...

 SCSI
 cable
  0|| adapter  computer (computer often acts like controller)
  1|| separate SCSI/HD controller  drive1,drive2
  2|| embedded SCSI controller on hard drive
  3|| embedded SCSI controller on hard drive
  4|| embedded SCSI controller on tape drive
  5|| adapter  perhaps another computer
   || etc

Actually, "adapter" is misleading, as what you really have is just another SCSI
controller on the bus.... specific to the computer. Those embedded SCSI
controllers are likewise specific to the HD/tape/etc drive that they are part
of. So...

1. Right. "SCSI drive" means the controller is embedded in with the actual
drive electronics. So you just need to hook it via a cable [see 2,3 above]. A
regular ST506 HD (or often, several) can be hooked up to a standalone SCSI/HD
controller also, for example an Adaptec 4070 [see 1 above].

2. No, those cards are for a PC bus. The second expansion board on the MM/1 has
a SCSI interface, which means any SCSI drive hooks up with a 50-pin cable and
you're rolling.

3. Sure. You can have up to 7 SCSI devices on the cable (8, counting the main
computer). Each one has jumpers to set its "device ID" number.

4. I think some drives now are set to 512-bytes/sector, and you can't change it
(PClone influence there). Older drives allowed changing (like my old Rodime
20meg SCSI HD... it could be set to almost any size.. so I used 256 for my
CoCo).

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