Floppy drive for Zenith 100

From: Don Maslin <donm_at_cts.com>
Date: Wed Feb 26 23:45:00 2003

On Wed, 26 Feb 2003 Innfogra_at_aol.com wrote:

> In a message dated 2/26/03 7:21:26 AM Pacific Standard Time,
> rigdonj_at_cfl.rr.com writes:
>
>
> > Correct, XEROX made a model 8/16 that had two CPUs, one 8 bit and 16 bit. I
> > THINK one was a Z-80 and the other was a 8086 but I'm not sure any more. I
> > used to have the docs for an 8/16 and I've been looking for one but haven't
> > managed to find one yet.
> >
> >
>
> Xerox made a couple of 8/16s. I have one of the 8086 second CPU boards for my
> Xerox 820-II. I was going to install it till a house fire melted the 820.
>
> The original 820 came with dual 8" floppies or an 8" floppy and an 8"
> harddrive and ran CPM. It was a spendy little computer for its time. Then
> they fit Dual 5 1/4" floppies in an external case, came out with a low
> profile keyboard and the add on 8086 Board. They called it the Xerox
> 820II-8/16.

The original 820 was a single board computer that used external
drives - two - in either 8" or 5.25" size. In either size they
were limited to single density. The next version, the 820-II
added two connectors to the board and one was occupied by the
Floppy Disk Controller (FDC) card which was both single and double
density capable. In the standard 820-II the second connector was
vacant, but could be occupied by an 8086 card giving a dual
processor capability. Additional external hardware could be added
such as the Disk Expansion Module (DEM) which provided for hard
drive capability as well as 5.25" DSDD floppies. When in DEM
configuration, the FDC card was replaced by the DEM interface card
and FD control was provided from the DEM. The 820-II-16/8 was
just such a configuration.

> IIRC the design was taken from the Z80 Big Board which was a popular kit at
> the time. It was mounted flat, underneath the CRT and looked much like a
> terminal.

I have not tried it with a Big Board, but I know that there is a
great similarity between the 820 and the Kaypro computers as a
modem program configured for one will run on the other.

                                                - don

> At the time the IBM PC came out the Xerox design was hopelessly outdated.
> They redesigned the case to a rectangular shape with a separate monitor ala
> the IBM PC. They used dual 5 1/2" half height floppies oriented horizontally.
> I never saw an actual one but IIRC they used the same Big Board coupled with
> the 8086 board that was in the 820 and sold it as the Xerox 8/16.
>
> It ran CPM, CPM-86 and MS-DOS ( IIRC to 2.11). However it was not IBM
> Compatible, and did not have IBM graphics.
>
> By the time it was ready the bottom had fallen out of the crossover market. I
> don't think Xerox sold any commercially. A liquidation company sold the
> remainder for about three years. I doubt they sold many, I bet most were
> scrapped for the drives.
>
> The Xerox 820 II was my second computer system and still one of my favorites.
> (The first was State Surplus Litton 1251 that I bought for $25.00) I have had
> almost all of the various models of the 820 go through my hands over the
> years. Besides my original melted one I still have another packed away with
> all it's SW. Someday it will run again.
>
> Paxton
> Astoria, OR
Received on Wed Feb 26 2003 - 23:45:00 GMT