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IBM XT 5160 E0 301 error on boot

Success! I received the nut driver and proceeded to disassemble the keyboard. First thing I did was unplug the mylar and boot the machine. No error! Also, a nice surprise was that the hard drive works perfectly. It booted up to some Peachtree software.

Next step was to remove all the plastic rivets and get to the mylar. Just for fun, with just the mylar connected, I booted up again. This time I got a F0 301 error. However, I was able to hit F1 and continue. Fortunately I don't need to see what the keys are to know where to type! I was able to exit out of the Peachtree software and pull up a directory of the hard drive. I was also able to read a 3.5" floppy I had lying around from my 386 days. I tried the B drive with the 5.25" but I don't have any DOS disks. It didn't like my single density Atari disks. Maybe I just need to format one with DOS.

I'll remove and clean the mylar up with isopropyl alcohol and see if I still get that F0 error. After that, I'll do the bolt mod. However, slight problem - the black plastic base where all the keys fit into is cracked in the middle. I don't think I did it, as I was aware this could happen and was insanely gentle, but I suppose I could have done it.

Is there somewhere I can get a replacement piece? The IBM part number stamped on it is 1385796. If a replacement isn't available, or they are ridiculously priced, I'll just try and use what I have.
 
You can check with unicomp and see if they sell something that will work. They show “cover sets and frames” on their site for $20, but I’m not sure if that includes the part you’re talking about.
 
Thanks, I submitted a sales ticket request to them. Hopefully they either have a NOS piece, or still manufacture it.
 
Got a response! They do still sell it. They call it the frame. Next paycheck I'll be ordering one. In the meantime, I'll take it all apart and clean everything individually. It's under replacement cover sets and frames. When you order, you select the type of frame and put the part number of your original keyboard in.
 
I repaired the barrel frame on one of my early square badged model M by plastic welding it with an old soldering iron. The hairline crack travelled almost totally across the whole frame and after welding it was far more ridged.
 

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Nice! That would work in a pinch. I only have my Hakko FX-888D soldering station. I'd have to buy a cheap iron to try that. The replacement frame is only $20 though, so I'm just going to order a new one. I'll still keep the old one just in case though.
 
I am happy to report the bolt mod was a success! It took way longer than I anticipated, but I now have a 100% fully functional 5160 XT. Total cost of all parts required: $35, plus $5 in gas to get it. (free Craigslist haul) I'd say that's a real bargain for a 5160 with 640K on the motherboard, a 1.44MB 3 1/2 floppy, 360K 5 1/4 floppy, 20MB Western Digital hard drive and a 5151 monochrome monitor.

Now excuse me while I enjoy some Hitchhiker's Guide to the Galaxy Infocom goodness on this lovely machine.
 
I have one theory regarding the 1390120:

20230802_171317.jpg


Looking at the 1986 IBM 5160 BIOS code above, after the normal keyboard reset it appears to test for `EA` instead of the normal `AA`, which *appears* to indicate that the attached keyboard is an "enhanced" model, and is the only way that the enhanced support is enabled in the BDA flag.

This seems problematic however, since as far as I've ever seen all XT BIOSes look for the `AA` (including any previous IBM 5160/5150 ones) to signify a successful reset - meaning if the 1390120 model returned an `EA` the BIOS would apparently give a 301 post error. As I've never comes across an XT compatible 101 key keyboard, converter (XT2AT) or emulator that failed this way, it would appear that was not carried over and never used by anything else. This would also seem that this keyboard and the 1986 IBM BIOS would be mutually incompatible with any other clone enhanced keyboards that return `AA` on reset, because in that case the 1986 IBM would not set the enhanced flag, and clone BIOSes would see the `EA` as some kind of error condition.

Anything to this theory?
 
Last edited:
640KB said:
Anything to this theory?
Click to expand...
I hadn't noticed that check for EA in the '86 dated BIOS'. I have updated my web page at [here].

At first, I thought, I bet the KYB_RESET subroutine is doing something slightly different to the one in earlier dated dated BIOS', and the enhanced keyboard responds with EA to that (and AA to earlier BIOS'), but both subroutines are identical.

I looked through some keyboard technical documents, and could not find any reference to EA.

Even in the '101/102-Key Keyboard' section of the later 5160 technical reference, AA is indicated.
1691191490162.png

So, was the EA an intention that was never followed through, aborted ?

More research required.
 
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