[sebhc] introduction

Barry Watzman Watzman at neo.rr.com
Wed Jun 29 06:17:38 CDT 2005


You may recognize me as I am a fairly major "SOL" collector.  However, I was
also the product line director at Heathkit while the H89 was being marketed.
There are several other key former Heath people here on this list, also.

There is a "Configuration Guide" for the H89 that I wrote while at Heathkit,
that became an official Heathkit document.  It's available online in the
Harte library, or I can send it to you.  It will probably help you out a
lot.  [Actually, I see from your list that you have the hard copy version.
Spend some time studying that document.]

The H-47 is junk, because of the junk Remex drives (which are,
unfortunately, not standard 8" floppies).  I'd be surprised if it works (not
all that many of them worked back in 1981).  There was no Heathkit product
that allowed the use of "standard" 8" drives with the H89.

There are two different 5.25" Heathkit floppy controllers for the H89, a
single density controller using hard sector diskettes and a double density
controller using soft sector diskettes.  Either or both can be installed,
but they take different media, and the boot media needs to be configured to
use them (there were 4 different disk systems available for the H89, the
"17", "37", "47" and "67").  There were also two major operating systems
available, CP/M and HDOS.  CP/M was standard CP/M 2.2 with a Heathkit BIOS,
and BIOS source code was provided, but the BIOS and the system regeneration
procedure were fairly complex.

I'm not sure what the CDR stuff that you have is, a memory disk card or some
high-density RAM card, I suspect.

The H-77 is just a case and power supply for two external 5.25" disk drives.
The drives are standard 5.25" drives.  You may have either the
Siemens/Wangco drives, which are single sided, or Tandon drives, which could
take on several flavors (including some that were 80 track 96tpi drives).
In any case, an H-77 case can be connected to either controller (a
hard-sector "17" or a soft-sector double density "37").  A major issue with
hard-sector "17"-based systems these days is getting hard sector (10-sector)
5.25" blank media.

Hope that this helps.

Barry Watzman
Watzman at neo.rr.com

-----Original Message-----
From: sebhc-bounces at sebhc.org [mailto:sebhc-bounces at sebhc.org] On Behalf Of
Jim Battle
Sent: Wednesday, June 29, 2005 2:56 AM
To: sebhc at sebhc.org
Subject: [sebhc] introduction

Hello, sebhc list members.

I'm new here, and new to the heath scene.

Recently I was given three H89 computers, an H47 dual 8" disk drive unit, an
dual 5.25" disk drive unit, along with some disks and docs.

One machine has a single full sized 5.25" drive and it gets the H: prompt,
and I 
can boot off of the internal drive (it is set up as the secondary drive).  I

have only one disk that wants to boot from that drive, running CP/M 1.34 or 
somesuch.  I tried hooking up the H77 to it but the H77 is wired up such
drive 0 in the external drive is mapping to drive 0 of the internal drive. 
Unfortunately, one of the 8" disk drives in the H47 box had its door broken
during shipping (my sister decided she didn't want it sitting in her
until christmas, so she "packed" it and shipped it :-( )

The second machine is for parts it appears -- it has no disk drives, is
some keys, and there is nothing on the CRT when I power it up or reset it. 
Perhaps it requires a simple fix, but for now, I'm assuming it is for spare

The third machine has two half high 5.25 inch disk drives.  Many of those
disks that weren't readable in the first machine had "CDR" written on the
and I had no idea what that meant.  When I opened the third machine,
around inside the case was a two board sandwich that was made by "CDR
inc".  It contains a Z80 and what might be 1 MB of RAM.  THe other big chips
it are a national semi DP8409AN-2 (which I think is a dram controller), a 
national semi MM58167AN real time clock chip, and a socket for a 40 pin
which is empty.  there is a 40 pin ribbon cable from one of these CDR boards
the original Z80 socket on the main CPU board.  The reason those boards and
other I/O cards were floating around was that this machine is missing the
cages that should be holding in those cards.  I guess I have found the first
for my parts machine.  :-)

I've had the courage to try the third machine after reseating the floating
like I think they should be and indeed it works -- there is a 1MB RAM disk
it runs a 63K CP/M.  The disk drive capacity is 780KB according to D.COM.
of the disks has the CBIOS for the CDR system.  When you boot a CDR disk, it

says: do you want a ram disk or not?  If not, then the floppies are drives A
B.  If you do request the ram disk, then there are other questions to answer

(should I wipe what is already in the RAM disk (it is battery backed up I 
guess), do you want one or two RAM disk partitions).  If there is one ram
of nearly 1MB, then the physical first floppy becomes drive b:.

None of the disks that boot boot into HDOS.  Perhaps some of the 8" disks
but that will have to wait for another night.

The docs that came with the machine include
	Heathkit Manual for the DIGITAL COMPUTER H88 assembly (595-2267)
	Heathkit Manual for the DIGITAL COMPUTER H88 operation (595-2268)
	Heathkit Manual for the DIGITAL COMPUTER H89A operation
	Heathkit Manual for the FLOPPY DISK Model H47 (595-2467-01)
	Z89-47 accessory (595-2473-02)
	H-88/H-89/Z-89/Z-90 Configuration Guide (597-2571)
	Instructions for the PROM UPGRADE ACCESSORY Model H88-7 (595-2547)
	Modification Kit for the H88/WH89 COMPUTER Model H88-6 (597-2171)
	Instructions for 16K MEMORY EXPANSION ACCESSORY Model WH88-16
	Monitor MTR-89 (595-2508) (this is a rom source listing)
	BIOS LISTING for CP/M 2.2.03 (595-2775)

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