GIDE ON A HEATHKIT
is a device that plugs into
the socket of your Z80 CPU and adds easy support for IDE hard drives.
This web page details how to use one with your Heathkit H8 computer
with a Z80 CPU card.
Note: The following section details using the GIDE with my Rev 1.8 Z80
CPU card for the Heathkit H8 computer. I've since redesigned my Z80 CPU
card and have GIDE support built-in. See my Rev 2.1 card in the PCBs
section for details.
The first step is to install the device in your system. For the
Heathkit H8 computer you'll want to use the cable attachment option.
This uses a short ribbon cable to plug the GIDE into the socket of your
Z80-based H8 motherboard. This is required to fit the GIDE within the
chassis of the H8.
In this photo I've installed the GIDE onto one of my H8-Z80-64
Z80 CPU cards.
Since I attached the GIDE onto the front side of the CPU card I had to
install the CPU card into the 2nd slot on the buss. A better approach
would probably be to attach the GIDE to the backside of the CPU card
and run the ribbon cable over the top to the Z80 CPU socket. Doing this
would allow you to move the CPU card to the first slot.
Once the GIDE is in place you should be able to power up the computer
and get the familiar beep along with the front panel LED display
lighting up. It is now time to boot into the CP/M operating system and
run the GIDETEST utility to verify the operation of the
If everything checks out you can begin the process of installing the
BIOS extension and formatting of the hard drive so that you can begin
using it. Download the Heathkit
GIDE support files
and transfer these to the Heathkit
computer using either the supplied H8D disk image file and an SVD
or by using my H8D Utility
and Dwight Elvey's
H89LDR to transfer the image over a serial port connection to a hard
sector disk in the H8 computer. The files you'll be interested in
are GBIOSWB.Z80, SLRASM.ZIP, GIDEFMT.COM
and IDEGEN.COM. The
GBIOSWB extension and IDEGEN utility were written by John D. Baker
and have been
slightly modified by me for the Heathkit computers.
boot your system directly off an SVD use the following boot images. It
is saved as a .SVD file (as opposed to a .H8D) and will boot you into
CP/M 2.2.03 with the GIDE BIOS extension and the ZCPR CCP. These images
are setup for use with the GIDE at port 80h and the terminal at port
350Q and INT 3. You should have 64K of RAM installed and the system
should be running at the standard 2MHz operating speed. There are two
images in the zip file. One is for warm booting from drive A and one is
for warm booting from drive E. You should first boot the image for
drive A then GIDEFMT and IDEGEN your hard drive. After your hard drive
is IDEGEN'd you can use the image for warm booting from drive E. You
cannot warm boot from drive E until it is IDEGEN'd which copies the
system tracks to the hard drive.
IDEGEN your hard drive so that you can boot from it first type MOVZ80
62 which creates a 62K CP/M image in memory. Then run IDEGEN and press
ENTER for source drive (the image is in memory) and type 0 for the
destination which is hard drive E.
2.2.03 62K with GIDE and ZCPR
for SVD boot
GBIOSWB.Z80 will have to be modified by you before using it. You need
to fill in the parameters for your hard disk (number of cylinders,
number of heads, sectors per track) and then assemble the source file
with SLRASM (Z80ASM). This should be done on the Heathkit computer
after you transfer the files. Another method you can try (and how I did
it over here) is to run a CP/M emulator like MYZ80 on your
XP PC and build the .COM file on your PC and transfer it over
to the Heathkit using an SVD.
Now that you have the GBIOSWB.COM file built it's time to get it
running on your Heathkit CP/M system. Do this by first creating a 62K
version of CP/M as follows:
you want to use ZCPR (recommended)
(MOVZ80 is included as part of the CPM_2_2_03_62K_ZCPR.H8D disk image)
Then SYSGEN a disk with this new CP/M image by immediately typing the
Just press ENTER when asked for source disk (the CP/M image is already
in memory) then type in the drive letter to write the 62K version of
CP/M to. Once a disk is sysgen'd you need to copy BIOS.SYS,
GBIOSWB.COM, GIDEFMT.COM, IDEGEN.COM and CONFIGUR.COM to it and then
boot with the new disk. When you reach the CP/M prompt you can type in
GBIOSWB to load the BIOS extension so that you can access your hard
drive. This extension installs itself into the upper 2K of RAM (above
the 62K CP/M image) and re-routes any requests for drives E: thru J: to
the GIDE. Now is also a good time to run CONFIGUR so you can setup
GBIOSWB to run automatically during a cold boot.
It's time to format the hard drive. At the CP/M prompt type the
Then follow the onscreen prompts to fill in the sectors per
track and number of heads. Look at the label on the hard drive for this
information. GBIOS sets up one head (or platter) per disk so that the
first platter is disk E:, the second one is disk F:, etc. Just make
sure you have at least 8MB per platter. If you have more then 8MB per
platter, the additional cylinders will just not get used so you don't
have to format them. GIDEFMT will automatically compute the
number of cylinders for you using the following formula:
8192000 / (sectors-per-track x 512)
As an example, for my Conner CFS1275A with 63 sectors per track I
needed 254 cylinders:
8192000 / (63 * 512) = 253.9 rounded up = 254
Remember that GBIOS uses one head (or disk platter) per disk. My Conner
drive has 16 heads but I only use and format the first 6. By specifying
the cylinders and heads to format you can reduce the
amount of time it takes to format the drive since only the portion that
gets used by CP/M will need to be formatted.
When formatting is complete you'll be able to start using the hard
drive. Switch to each drive (E: thru J:) and then type STAT
get the available space of the hard drive partitions.
I installed my hard drive inside the H8 chassis as shown in the
following photo. At this time I'm using an external PC power supply to
power the hard drive but eventually I will probably power it from
within the chassis.
2.1 H8-Z80-64 CPU Board
of 9/2/2009 I've redesigned my H8-Z80-64 CPU card which now has GIDE
support built-in. All you need to do is buy the GIDE chips
and plug them into my CPU board. The steps for
installing the software above are exactly the same.
This concludes the steps for getting the GIDE up and running on a
Heathkit H8 computer running the CP/M operating system.
Here are some informative links relating to the GIDE:
GIDE's can be ordered from this link:
For U.S. residents GIDE chips can be ordered from Terry Gulczynski
SEBHC.ORG Home Page
Google Group Link
November 16, 2009