Aloha to a Hawaiian TRS-80 Model 100

Well, finally got a chunk of free time to get back to my ‘Mod­el 100 school’. My goal is to learn about these m100s through hands-on learning.

A new friend (Hi Larry) sent me his ail­ing m100 to fur­ther my edu­ca­tion. Who knows? Maybe I can get it run­ning again — it’s a nice look­ing machine!

About a month ago I first opened it up and gave it a visu­al inspec­tion. Clean and no obvi­ous sign of capa­cit­ors fail­ing or failed. The Memory bat­tery is start­ing to show signs of crys­tal growth, so it’ll be com­ing out soon.

Upon power up, the unit shows a screen of scrambled pixels. Not garbled char­ac­ters, just pixels, or miss­ing pixels.

And that’s where I left it a month ago.

Tonight I man­aged to get my work­bench in shape (my first oscil­lo­scope — more learn­ing!) and open the m100 and start tak­ing some basic readings.

  • VDD 5.179
  • VEE ‑4.961
  • VB 5.144

Next, start tra­cing down the RESET signal.





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