psx.wiki

EXP2 Delay Register Read-back: Difference between revisions

Revision as of 04:48, 23 October 2026
RemmyLee
(Main page: drop the Hardware Tests lede)		Revision as of 05:11, 23 October 2026
RemmyLee
(Hardware tests: 72 more test pages, listed on the main page by area; RUN.toml no longer published)
Line 1:Line 1:
+---
+title: EXP2 Delay Register Read-back
+type: test
+summary: Writes the expansion region 2 delay/size register with four values and reads each back.
+category: Hardware tests
+info: Machine = SCPH-5501
+info: Program = dev8-readback (pcsx-redux nugget)
+---
+
+## Overview
+
+The program writes the EXP2 delay/size register at 1F80101Ch, the register for [expansion region 2](/hardware/expansion-port/) (DEV8), with four values and reads each back twice. It then puts back the value the register held on entry.[^out]
+
+## Results
+
+The register held 00080777h on entry. Each value written read back unchanged on both reads: 00070777h, 00080777h, 00000777h and 00010777h, so bits 16 to 19 of the register keep any value written. The register read 00080777h again after it was put back.[^out]
+
+## Runs
+
+### 22 October 2026 link-2
+
+Raw output: [DEV8READBACK.txt](/tests/raw/20261022T2245Z-5501a-link-2/dev8readback/DEV8READBACK.txt) · [bench.txt](/tests/raw/20261022T2245Z-5501a-link-2/dev8readback/bench.txt)
+
+DEV8READBACK.txt:
+
+```
+D8RB entry=00080777
+D8RB wrote=00070777 read=00070777 00070777
+D8RB wrote=00080777 read=00080777 00080777
+D8RB wrote=00000777 read=00000777 00000777
+D8RB wrote=00010777 read=00010777 00010777
+D8RB-DONE restored=00080777
+ResetGraph:jtb=801e78b8,env=801e7900
+```
+
+bench.txt:
+
+```
+257 bytes of TTY text in psx.log
+```
+
+## References
+
+[^out]: Hardware test run 20261022T2245Z-5501a-link-2: [dev8readback/DEV8READBACK.txt](/tests/raw/20261022T2245Z-5501a-link-2/dev8readback/DEV8READBACK.txt). The program is nugget's tests/dev8-readback, https://github.com/pcsx-redux/nugget
+