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28131Re: vintage SRAMs self healing

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  • s100doctor
    Nov 16, 2012
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      --- In midatlanticretro@yahoogroups.com, "Mike" <mike@...> wrote:
      > HI,
      > Boy, you guys are tough reviewers. :-)
      > Other than testing speed, this test is about as complete as it can get. Signals look remarkably good, edges are fine with no ringing, overshoot or undershoot.
      > The nice thing about this tester is how quickly I was able to put it together. 3 evenings for the 1101 tester and a couple of more hours to create the 2102 version. Directly interfacing to a processor would have taken considerably longer.
      > The other interesting thing is that I tested 200 1101 parts, with only 1 part that I damaged during development of the test, failing.
      > I'm currently investigating whether tarnish is a contributing factor.
      > Regards,
      > MIke W.

      I largely agree with you - this is a nice bit of work. One could test most any bit of logic with variations of this Apple II code and hardware. And it's not hard to do the same logic, with a Z80, a 6800, etc. It might be fun to use a microKIM, could even use most of your code! Plus, the microKIM could probably implement an at-speed tester too, plenty of address space "open". Even I, "the S-100 guy", have one of those.

      I'm curious...I think, reading your read/write subroutine, you are probably running the RAM at say 20-25 microseconds? Given an Apple II at 1MHz? If you looked at the signals, you probably know how fast your scope was sweeping to see one access time.

      I'm inspired to make something like this, if I get a Z80 prototype running next year. Thanks for keeping the 1970's on the bleeding edge again. Well....maybe the leaking edge.....;)

      Herb Johnson
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