Some Maintenance on a Canon A-200 20HD

Quite some time ago when I was back at my parents place I had a look at a Canon XT clone, the A-200 20HD. There were a few basic repairs needed, so when I recently saw my parents I spent some time on it.

First thing I did was remove the Ni-Cad battery from the memory expansion board, to prevent any future problems with leaks. Leaky batteries are very hazardous, and can destroy whatever board they happen to leak upon. This often can damage a machine beyond repair. This battery had not leaked yet, but was not really holding a charge. It is a 3.6V  50mAh battery made by Yuasa from Japan, so it’s likely a quality cell, but still best to remove it. I wonder if given its small capacity I could use a super capacitor in its place.

The battery was the main reason I looked at the machine, but I remembered the MFM hard disk wasn’t spinning up. I had to test the machine anyway, to ensure it was working correctly after removing the battery. So I thought I’d try to get the drive spinning again. I tapped and banged it strategically a few times and that didn’t really help. So I rotated the stepper motor that drives the heads one step and it worked pretty much immediately. I wouldn’t normally do that given the risks, but I would have had to open the drive otherwise.

I rebooted the machine and MS-DOS 3.3 booted up of the hard disk without issue. Strangely it seemed to be only formatted as a 10MB disk, I had a look around the machine and found we had put a few games on it for testing. Here we see the menu screen installed on this machine called admast. Before MS-DOS 4.01 there was no shell or menu system included, so simple menu systems like this one filled the role.

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The three games I had installed were Megapede, Nyet, and Cyrus Chess. All these games support using the MDA cards text mode for the simple graphics that they have. They also all run surprisingly well. Nyet runs pretty much the same as it does on faster machines. Megapede runs well, its speed is CPU dependent and this machine seems to be about ideal. Cyrus chess works about the same as a newer machine, minus the graphics, and it obviously takes longer to work out a good move.

I’m quite pleased to have gotten the machine working again as it would have to be the oldest machine anyone in the family owns. I’ll have to try some more software on it (if I can find any that is compatible) and see if I can get a hercules compatible graphics card. It would be cool if I could get an old version of simcity working on it.

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