One thing I noticed is that if you power it up after a few hours of being off, you have to cycle the power a few times to get it to boot off of the floppy! Even if I unplugged the HD cables, so that only the floppy drive is connected to the controller card, it still does that. This morning I couldn't get it to boot from the floppy no matter how many times I cycled the power. Then I remembered that the "as found" terminating resistor (on the floppy drive) was only plugged in on one side. I should have left it that way despite what the manual said. Now it boots, and I can do a "dir", however if I try and load any of the programs on the disk I get an error. More troubleshooting ahead! However it will have to wait. I need to get back to my Mod8 project.
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Pretty sure the MFM HD is poached. Was able to boot from a floppy disk I made from a TD0 image I found on the net.
Fixed the power supply issue. Now I need some advice on the drives. It doesn't seem to want to boot from the hard drive and I have no Kaypro floppies. Both the HD and the floppy drive lights remain on after powering up. The screen displays "* Kaypro 10 v 1.9e *". Is the hard drive poached or a controller card issue? No idea at this stage, though I suspect the MFM drive is pooched.
Update on TRS-80. Took it apart and it turns out that the video RAM is soldered in, so it can't be a poorly seated chip. Bypassing the expansion box doesn't make any difference. Here are some observations I noticed. 1. Spaces look like commas , hence the funny boot screen. 2. Number keys generate lowercase letters instead of numbers 3. Special characters are incorrect. 4. Basic does work. I can type PRINT "HELLO WORLD" and it prints HELLO WORLD as it should. 5. Shift doesn't seem to have an effect on the case of most characters typed out. Fortunately someone on a Facebook group mentioned a "lowercase" mod for the TRS-80. Turns out it is not compatible with Level II BASIC. It was quite a lot of work to remove this mod from the computer. Several jumpers had to be removed and several cut traces had to be found and repaired. It took about a dozen tries before I completely removed the modification. Actually it was a burnt out fuse and a bad power cable. However there is something else is wrong. Though it powered up, it soon started to smoke. Turns out that a RFI filter for the mains fried.
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AuthorCharles Baetsen holds a Bachelor and a Master's degree in Engineering Physics from McMaster University in Hamilton, Canada. Archives
October 2023
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