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--- title: Expansion Region 2 Access Width type: test summary: Reads and writes expansion region 2 at every width under two bus width settings. category: Hardware tests info: Machine = SCPH-5501 info: Program = exp2-width (pcsx-redux nugget) --- ## Overview The program reads 1F802000h in [expansion region 2](/hardware/expansion-port/) with LB, LH and LW, and writes 1F802040h and 1F802041h with SB, SH and SW. It prints a line before and after each access, so a hang shows as a BEFORE line with no AFTER line. It runs the whole set once with the EXP2 delay/size register (1F80101Ch) at its value on entry and once with the register set for a 16-bit bus.[^src] ## Results Every access completed under both settings. No access raised an exception or hung the console. The register read 00080777h on entry. Reads of 1F802000h returned FFh, FFFFh and FFFFFFFFh for the three widths, which is the value of an empty bus on a retail board.[^out] ## Runs ### 22 October 2026 link-3 Raw output: [EXP2WIDTH.txt](/tests/raw/20261022T2245Z-5501a-link-3/exp2width/EXP2WIDTH.txt) · [bench.txt](/tests/raw/20261022T2245Z-5501a-link-3/exp2width/bench.txt) EXP2WIDTH.txt: ``` EXP2W-START dev8=00080777 bios BEFORE lb bios AFTER lb ff bios BEFORE lh bios AFTER lh ffff bios BEFORE lw bios AFTER lw ffffffff bios BEFORE sb bios AFTER sb bios BEFORE sh bios AFTER sh bios BEFORE sw bios AFTER sw w16 BEFORE lb w16 AFTER lb ff w16 BEFORE lh w16 AFTER lh ffff w16 BEFORE lw w16 AFTER lw ffffffff w16 BEFORE sb w16 AFTER sb w16 BEFORE sh w16 AFTER sh w16 BEFORE sw w16 AFTER sw EXP2W-DONE ResetGraph:jtb=801e78b8,env=801e7900 ``` bench.txt: ``` 444 bytes of TTY text in psx.log ``` ## References [^src]: pcsx-redux nugget, tests/exp2-width/exp2-width.c, header comment. MIT License. https://github.com/pcsx-redux/nugget [^out]: Hardware test run 20261022T2245Z-5501a-link-3: [exp2width/EXP2WIDTH.txt](/tests/raw/20261022T2245Z-5501a-link-3/exp2width/EXP2WIDTH.txt).