Z80 CCF SCF Outcome Stability - redcode/Z80 GitHub Wiki
Platform: ZX Spectrum
Author: Helcmanovsky, Peter
License: MIT
Links: GitHub
| Version | Release date | Links | Download |
|---|---|---|---|
| v1.1 | 2022-02-17 | GitHub commit | tar.xz (hosted) - zip (GitHub) |
| v1.1 | 2022-02-02 | GitHub commit | tar.xz (hosted) - zip (GitHub) |
| v1.0 (hack) | 2022-02-01 | Discord post | tap (hosted) - tap (Discord post) |
| v1.0 | 2022-02-01 | GitHub commit, Discord post 1, Discord post 2 | tar.xz, tap, trd (hosted) - zip (GitHub) - tap, trd.zip (Discord post) |
| alpha | 2022-01-31 | Discord post | tap (hosted) - tap (Discord post) |
This tests stability of outcome of ccf/scf instructions, if the CPU does produce random values in flag register, the test will display red attribute square. For more details check the source comments.
This is near impossible to fail at FPGA or emulator, as it would need to add randomness intentionally, but some clones of Z80 CPUs in some machines do produce random values in undocumented flag bits (YF/XF), and this test can display whether the machine does produce random values at all, and whether it can be pinpointed to certain frame period like drawing PAPER area.
| v1.1 | v1.0 (hack) |
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| v1.0 | alpha |
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- 48K mode: https://www.youtube.com/watch?v=Qz0HrpdBr2Q
- 128K mode: https://www.youtube.com/watch?v=3W9TN3YrUDs