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added initial wyse 60 repair

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saji 2025-05-02 21:31:07 -05:00
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content/blog/wy-60-repairs/wy-60-repairs.md
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@ -100,19 +100,44 @@ Uh, guys?
Image of more cold joints on a different chip. Image of more cold joints on a different chip.
It can't possibly be this, right? U17 and U15 are part of character storage, and It can't possibly be this, right? U17 and U15 are part of character storage,
I did see the font RAM output non-zero, meaning it had to have rendered and I did see the font RAM output non-zero, meaning it had to have rendered
something! I quickly cleaned up the joints and powered it on. I couldn't see it something! I quickly cleaned up the joints and powered it on. I couldn't see it
at first, but it worked. This highlights the two styles of troubleshooting: at first, but it worked.
# Takeaway
This highlights the two styles of troubleshooting:
1. Hypothesis -> Solution 1. Hypothesis -> Solution
2. Hypothesis -> Validate -> Solution 2. Hypothesis -> Validate -> Solution
It feels pretty good to zero-shot a repair or fix, but it also can leave you with blind spots. It feels pretty good to zero-shot a repair or fix, but it also can leave you
In my case, I didn't want to try to probe the board while hot, but later it became necessary unless with blind spots. In my case, I didn't want to try to probe the board while
I just started replacing chips indiscriminately. Once I started probing, I wanted to find something that hot, but later it became necessary unless I just started replacing chips
seemed "off" before going further. I would have noticed the character RAM eventually, if I finished my indiscriminately. Once I started probing, I wanted to find something that
testing of the Attribute RAM. In this case it was easy to spot visually and so I didn't need to test it seemed "off" before going further. I would have noticed the character RAM
any further. eventually, if I finished my testing of the Attribute RAM. In this case it was
easy to spot visually and so I didn't need to test it any further.
While I was working on this, my friend was using his unit to develop a USB
keyboard adapter. His unit was slightly more yellow and has some centering
issues, but otherwise is fully functional. By the time I had mine figured out,
the firmware was mostly complete, so it was a quick flash away. I might blog
about it some time, but the protocol is really simple.
I'm typing this last portion in Vim on the terminal, using the VT100 mode.
( image of editing this post with the terminal )
# Next
It's not perfect. I don't know much about ye olde terminal behaviors
and finding replacements for modern tools that weren't built
with a VT100 compatible in mind is a task of itself. The flow control seems
to be DTR-based, which Linux doesn't support natively. We might be able
to hack around that with a shim but that's a problem for later. It works
fine at 9600 baud using software flow control.
To the folks who rave about the terminals of yore, I get it now.