Re: Can a GS or IIe use LS120 drives?

[dempson@actrix.gen.nz (David Empson)]

Supertimer <supertimer@aol.com> wrote:

> How difficult would it be to make an SCSI to ECP/EPP parallel
> converter box?  The Windows/DOS PC units have ECP/EPP cable
> units that convert to SCSI.

There are major differences between a simple parallel port (even a smart
one) and a SCSI port.

These "cable units" to which you refer are just using the parallel port
as a communication medium to get SCSI command and data in and out of the
computer.  They would need software in the computer to implement a
standard SCSI API, and there would have to be a converter box that
implements some of the timing-critical SCSI stuff.

SCSI is more than just an electrical standard - it also defines the
protocol used over the cable, how devices are categorised, command sets,
etc.

> Can a unit that converts in the opposite direction be made?

Possible, but difficult.  As far as the computer is concerned, it would
have to be a full SCSI device (probably not of any standard type) which
provided the physical connector.  This means it would basically be a
small computer in a box with a SCSI interface on one side and a parallel
port on the other.  It would be limited in what it could achieve
compared to the PC's parallel port, because the CPU would not have
direct access to the port hardware (at sufficient speed).

I think a better option (and less work overall) would be a new parallel
interface card which plugs into a slot.

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand