Posted By azog on April 17, 2012
This is a project I’ve been working on for some time. But it doesn’t work. I normally don’t like to post a half-assed project like this, but perhaps the rant will help me think of something, or perhaps someone will stumble on this and have an idea…
This is the GIDE (generic IDE) kit for the P112. This is built and installed. Hard to tell, but the P112 is below the GIDE, and connects via a three row series of headers near the left. I had to remove the battery from the P112, since it stood too tall to allow the GIDE to install. This is/was a known issue, and you can see that I’ve simply placed the battery on some double-sided tape and ran three conductors of some ribbon cable back to the P112.
The Compact Flash interface is not part of the GIDE kit. I purchased that separately for like $5 on ebay, shipped from Hong Kong. They’re really cheap. There’s no logic on the interface at all. I think CF is actually a subset of IDE.
The 128mb is a card I had laying around, and seemed like a reasonable size for an 8-bit system. For those who’ve never used a CP/M system, and are used to terabytes of disk space, 128mb is huge.
The CF interface is plugged directly onto the GIDE and uses a 3.5″ power connector. IF I ever get it working, I’ll need to preposition it so that it fits inside the enclosure. I wonder if there are 90 degree gender benders for headers? But that’s for a later date…
The GIDE arrives in a kit that is significantly easier to build than the P112. That’s because all the logic is inside two GALs, so the developer of the GIDE must have spent a good portion of time developing the GALs.
There are a couple of options you can select during building, the most important being how the GIDE will install onto the P112. If the GIDE is going on top, like mine, the headers get soldered from the component side. If the P112 is on top, the headers get soldered from the solder side.
I chose to add one other option mentioned in the build guide, a DIP switch for the address selection.
You can see the DIP switch at the upper right, and it is set for 50H, which is the default. I could have hard-wired it with jumpers, or even put a socket, but I opted for a DIP switch because, even tho it’s unlikely I will ever change the address, it gives it a really good visual finish. Yea, that’s a bit of vanity.
The GIDE comes with a boot disk, but it does not boot. If you look at a previous post, I mention I am having issues booting some of the disk images. The provided boot disk behaves in the same way, reporting “OS loaded, booting…” and then ceases.
CP/M 3.0 boots, but when I run fdisk, it reports it cannot read the IDE partition, which I am assuming means it cannot FIND the IDE device.
It these intermittent issues that are causing me frustration. If CP/M 3.0 boots, why doesn’t CP/M 2.2 or Z? Each time I create a disk from an image, I format it, and re-write the image, and then write-protect the disk to make sure nothing gets accidentally erased.
If I accidentally blew the disk controller chip (the other SMT device besides the Z180), I would imagine it wouldn’t boot AT ALL. If I accidentally blew the GALs, then the same behavior above should be apparent.