Making up a diagnostics board to help me troubleshoot my Mod 8 restoration woes. Still lots of wiring to do. Thirty three signals, 66 wires, plus ground and +5 to the chips and a few other wires. About half way done.
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AftAfter replacing the TTL chips, I had some limited success in resurrecting this C16. After I turn it on, it come up with a blank screen, or a garbage screen. Then if I hit the reset button, it comes back with either a garbage screen or the proper boot screen. I swapped in various PLAs, CPUs, and TED chips and the result was the same. However after a bit, I could no longer get it to go to the boot screen, no matter how many times I hit the reset button. About the only thing I did not replace was the memory chips. Could this be an issue with those? The video below is what gave me the idea to go after the logic chips. Rebuilt my 1702A EPROM programmer so that all those ugly "wall warts" are hidden in this case. Also built my latest revision of my Vintage EPROM reader for the Arduino.
Today, I assembled two of the reproduction boards I had made up for the Mod 8. These are the 8008 CPU and the buffer board. Using my original Mod8-2 TTY, and my Mod8-9 ROM/RAM boards, I should be able to get it to run. Hopefully I don't fry my 8008. Have to do some voltage checks etc before I insert this card.
Today I received the reproduction boards that I designed from Seeed Studio in China. They look excellent. Now it is time to assemble and test them out. Hopefully there are no major errors. This past weekend, my son and I drove 8 hours to Pottstown, Pennsylvania to check out Kemner's Surplus before the place closes. This is a place I have been meaning to check out ever since I have heard of it. They had all sorts of vintage electronics, and I was hoping to find some old S-100 boards, or some old MIL or Celestron boards. The place announced that they were closing about a month or two ago, so a lot of their good stuff was gone, however they still had a lot of interesting items to go through. I ended up buying a spare TI-99/4A, a black cassette deck for the PET, and an authentic Apple ][+ floppy drive for my Apple ][+ computer. I also ended up buying lots of small items such as 1970's ic sockets (red, blue and other colours), and a few other items. Over all it was a fun trip. I had to go see it, even if it I didn't find what I was really looking for. |
AuthorCharles Baetsen holds a Bachelor and a Master's degree in Engineering Physics from McMaster University in Hamilton, Canada. Archives
February 2024
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