I've found a Z80 processor and a TC5564APL-15 8K static ram chips, and I want to test the RAM chip, because it's really old and I'm not sure that it's not damaged. I do not have any experience with Z80's and RAM chip's, I'm not even sure that I didn't damage it while desoldering. I found THIS forum link, where a guy wanted to use a different RAM chip, but the code looked OK and I've took it. I did some modifications:

  • I only own one 74HC595, so I used that, I've connected the remaining address lines to 5V via 200Ohm resistors
  • I did not use any capacitors.
  • I've changed some connections.

Here's the modified code: https://pastebin.com/9nfTQY8X (Sorry for PB)

So it SHOULD print "0 0 0 8 / 0 0 0 8" to the serial, but it prints "0 0 0 8 / 8 8 8 8". The reason is unknown. Every other number works, I only found that specific bit not working correctly.
I'm not sure. Can my RAM chip be broken, or the circuit causes the problems?

  • Add a capacitor (0.1 uF at least) to the RAM chip. Commented Apr 1, 2017 at 8:24
  • 3
    I'm voting to close this question as off-topic because it's about Z80 and old memory chips; no Arduino involved.
    – user31481
    Commented Nov 15, 2017 at 21:04
  • The "modified code" on PasteBin has been deleted so there is definitely no way to answer this question as it stands.
    – per1234
    Commented Nov 15, 2017 at 21:56


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