Silent Q

Azog's little slice of the world. Whee.

P112 and GIDE (revisit)

Posted By on May 29, 2013

This is a project that’s been kicking around for some time, and I finally got up the gumption to have another crack at it.

I built a P112 some time ago, and then added the GIDE. This was before the Kickstarter campaign.

After building everything, I got it mounted in an enclosure that was originally an HP drive module. The GIDE mounting orientation is not going to remain as in this photograph. I have ordered some 90 degree headers so I could mount it horizontally, and be able to (hopefully) put the cover back on the whole thing.


Along the way, I ran into various stumbling blocks and user errors. I ended up putting everything aside, only to pick it up and periodically noodle with it.

Finally, with the help of Hector (part of the conversation you can see on the GIDE link), most of my issues were resolved. Now it was time to work on getting the GIDE configured, an operating system installed and booting directly from the GIDE drive.

I am going to focus on BPBIOS (Banked/Portable BIOS), because that works. I would actually prefer to use CP/M 3.0, but a different set of issues appear when going that route. I will talk about that later.

While getting my mental state prepared to tackle this, once and for all, I noticed that a new version of BPBIOS was posted, this time as a complete hard drive image, so I opted for that.

If you use this new image and write it directly to a CF card, the below installation process is going to be different.

Most of this is going to be notes to myself, but if others find it useful, so be it. I did eventually work out the installation process, because I like to make sure I understand something as fully as possible. The most important thing I ran into was the need to use BPCNFG to ensure that logical drive A: was pointing to the first hard drive partition. Otherwise, if logical drive A: points to the floppy, the system will load the bootloader from the GIDE, but continue to boot from the floppy.

First ensure that the BIOS parameters are configured properly for the CF card. In my case, with a 128mb card. Somewhere, I don’t remember where, I found the CHS parameters as 980 cylinders, 8 heads, 32 sectors.

Once setting the CHS (and any other BIOS parameters) and booting off the floppy drive with the BPBIOS floppy, make sure to load one of the dynamic images, because it seems that the GIDE “drivers” are not part of the base 64k boot. I load BANK1M1F (1mb RAM, 1 floppy).

When the system is booted, the floppy drive will change to F: and the hard drive will be A:. You will probably receive errors when the startup script(s) tries to run, but mostly, they can be ignored. You’ll probably be on the A: drive by default, so make sure to look on F:, the floppy. Most of these below are on F15:

* IDEINIT.COM, SHOWHD.COM or HDIAG.COM will give you GIDE parameters.
* HASHINI.COM to format the GIDE drive.
* BPSYSGEN.COM to copy the floppy boot tracks to the GIDE.
* BPCNFG.COM, using the “Disk” option to read the book tracks of drive A: (which is the GIDE drive, don’t forget):

In BPCNFG.COM, use the various menus to ensure that the baud rate is correct, that the GIDE CHS matches, and that A: is pointing at the GIDE (not the floppy)

* Copy that floppy
* BPCNFG.COM on one (or all) of the images (BANK*.IMG), to make sure the same parameters match.
* Remove the floppy, boot off the GIDE, and cross your fingers.

The above is for building a system from a boot floppy. If you are using the (new) disk image in the link at the top, the only problem I ran into was making sure the CHS parameters matched the boot track and the image file. Here, I had to boot the floppy, and use BPCNFG.COM on the boot track of the GIDE drive (A:), and the image (BPSYS.IMG) to make sure the CHS matched.

When all is done, if no errors, you should be able to boot:


There is a prompt in the startup script to load the banked/portable image BPSYS.IMG. I will edit that out to load this system by default. I personally see no need to run a base 64k system, and if I do, well, it’s easy enough to revert.

Now, I mentioned that I wanted to use CP/M 3.0, but I ran into (only) one problem. While the CP/M 3.0 disk boots, I was able to use the FDISK.COM program to partition the disk (using the “standard” boot code) and format the GIDE disk (INIC.COM, I think). Once that was done, I could not remember/figure out how to copy the boot tracks from the floppy to the GIDE drive. Perhaps if someone ever stumbles on this, they’ll refresh my memory, or correct my errant ways.

I’m glad to have gotten this far. I always hate leaving things half-assed.


Leave a Reply

Please note: Comment moderation is currently enabled so there will be a delay between when you post your comment and when it shows up. Patience is a virtue; there is no need to re-submit your comment.