4 Feb
2000
4 Feb
'00
2:46 p.m.
That's correct, Eric, it's a direct replacement, functionally, for the 1793,
with an analog clock extraction circuit. It has the limitation that the
analog clock processing circuit requires a different lowpass filter for 8"
and 5-1/4" drives, and, IIRC for FM or MFM.
The 9216 and 9229 are external clock recovery circuits tailored for the 179x
series, but can be replaced with a PAL. The 8-pin 9216 is pretty handy, but
doesn't handle the write-precompensation which the 20-pin (?) 9229 does.
Dick
-----Original Message-----
From: Eric Smith <eric(a)brouhaha.com>
To: classiccmp(a)classiccmp.org <classiccmp(a)classiccmp.org>
Date: Friday, February 04, 2000 1:46 PM
Subject: Re: What's a WD2793A chip?
external
In going
through and sorting my piles of classic ICs, I ran across this
Western Digital WD2793A chip. What is it?
It's a later replacement for the 1793 FDC. But not a drop-in replacement.
It has an on-board analog data separator, while the 1793 required an data separator.
Some of the other 179x replacements had better digital data separators.
I've personally always had good luck using the 179x with external
SMC 9216 or 9229 data separators, which are probably hard to get by now.