What's a WD2793A chip? - test-drb@ccmp.vtda.org

4 Feb 2000

Be careful what you assume about this chip.

As I wrote before, the external lowpass filter is different for different
data rates, so if you want to use both 5-1/4" and 8" drives, (and the
3-1/2"
ones that look like 8") then you need two lowpass filters.  These can be
hooked up very simply today as there are analog multiplexors with on the
order of 1 ohm of on-resistance, though back then it was necessary to use
relatively costly low-on-resistance D-mos switches.  I very much prefer the
digital approach, which, then, was the only real alternative.

Dick

-----Original Message-----
From: Dwight Elvey &lt;elvey(a)hal.com&gt;
To: classiccmp(a)classiccmp.org &lt;classiccmp(a)classiccmp.org&gt;
Date: Friday, February 04, 2000 6:23 PM
Subject: Re: What's a WD2793A chip?

...
 Allison J Parent &lt;allisonp(a)world.std.com&gt; wrote:
>
> <In going through and sorting my piles of classic ICs, I ran across this
Wes
...
 > <Digital WD2793A chip.  What is it?
>
> Take a 1793 and put some of the stuff needed to make it useful on the die,
...
 > call it 2793.  Basically it's a 1793 with data
sep and precomp logic built
...
   on. 
Hi
 Anyhow, if anyone wants the schematic for the iSBX card
I have with the 2793, I can trace it out for someone.
Just let me know. It has all of about 4 chips.
Dwight