18 Nov
2005
18 Nov
'05
6:36 p.m.
On 11/18/2005 at 1:17 PM Brad Parker wrote:
I've just never looked into pertec. Is it ttl? It
would be interesting
to see what signals you have to wiggle and how the data goes across.
It's single-ended OC TTL with 220/330 termination. Very "dumb" interface
with no handshaking--just strobes from the drive. On read, the drive
presents data and says "here it is" and on write the drive says "I'm
grabbing the data that you've hopefully set up already". Commands
basically involve asserting a number of signals corresponding to what you
want to do and then pulsing the "IGO" line for at least a microsecond.
Status lines take two forms--one type is static (e.g. write enabled), the
other is pulsed during the course of an operation (e.g. there was a parity
error on that frame). You even have to furnish the parity bit for writes.
There is a brief description of the signals in the back of one of the
Overland data drive manuals and I think I've seen another document on the
web.
Well, like I say, I want to stew on this one awhile.
Cheers,
Chuck