EdS
August 26, 2019, 9:05am
1
An interesting and long-running thread over on mastodon, as niconiconi designs, builds, and debugs a Z80 system on a breadboard. A calculation of digits of pi goes wrong, and is eventually traced to a memory timing problem.
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:oh_no: I loaded the π program to my breadboard #Z80, and the computer gives a different result on each run, none is correct... It must mean there's a hardware-level memory issue that corrupted some bytes, then got amplified by the...
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Finally, I probably found the culprit of memory corruption: a timing violation.
A write operation to SRAM can be initialized by pulling WRITE low, then ENABLE the chip, so I thought it's not necessary disable the output via OE...
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After fixing the "memory write" timing violation, my breadboard #Z80 completed the π calculation program flawlessly, and was able to calculate π to 500+ digits.
In the troubleshooting process, boards were rewired based on a...
Entropy seems to be winning, when it comes to the implementation:
The start of the thread is here , I think.
The second implementation is on home-built PCB:
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Oh wow, that is some breadboard set-up.
Not sure I would go this route: I might used a wire-wrap board instead.
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