2 Nov
1999
2 Nov
'99
9:12 a.m.
It might work better if you use an unused gate or some such. Phantom often
has numerous loads on it, so you could consider a pair of OC gates if
they're available. Otherwise, a SCHOTTKY diode should suffice, since its
forward voltage isn't enough to confuse any other device into missing the
LOW on the PHANTOM line.
Dick
-----Original Message-----
From: Bill Sudbrink <bill(a)chipware.com>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Tuesday, November 02, 1999 3:06 PM
Subject: RE: S-100 phantom (Was: RE: Northstar Horizon)
Exercising a little more brain power, I see I'll need to put a
diode in there to keep someone elses phantom from activating this
PROM.
So My Compupro RAM16 (64k static) in the NS* (system
A) has all banks
enabled and if we hit e800H the FDC forces phantom/ and the ram16 is
deselected for that address.
Ah... I see... Now, the 4FDC does not have any connection to
pin 67, so it is not using phantom. But it should be easy to
implement... Can I just take the /CS (-NOT- chip select) pin
from the 2708 and wire it to 67? Maybe I need to -NOT- it first?