GPU Info Index 08h

Reads GP1(10h) index 08h and the other unused info indices on a v2 GPU.

This is an old revision of this page, as edited by RemmyLee at 05:11, 23 October 2026. Edit this revision | Latest revision

Overview

GP1(10h) asks the GPU for an internal value, which the CPU then reads from GPUREAD. The program reads index 08h and its mirror 18h. It also reads the unused indices 06h and 09h to 0Fh.¹

Before each read it sets the texture window with GP0(E2h) and reads index 02h, which loads that texture window value into GPUREAD. An index that returns nothing therefore leaves a known value in GPUREAD, and an index that returns zero replaces it. Index 08h is read with GP1(09h) set to 0 and again with it set to 1 and to 3.¹

Results

Index 07h returned 00000002h, which is the version of this GPU. Index 02h returned the texture window values that GP0(E2h) set, 000ABCDEh and 00054321h.²

Index 08h and its mirror 18h returned 00000000h under every GP1(09h) setting. They replace GPUREAD with zero.²

Indices 06h and 09h to 0Fh never returned zero in this test. Each returned a texture window value from an earlier index 02h read. The GPU state test, which loads GPUREAD with a VRAM read first, found 00000000h at the same indices.²

Runs

22 October 2026

gpuinfo8/GPUINFO8.txt

GI8-START version=00000002 stat=d606200f
GI8 control idx=02 A=000abcde
GI8 control idx=02 B=00054321
GI8 gp1_09=0
GI8 vram idx=08 primedA=00000000 primedB=00000000
GI8 vram idx=18 primedA=00000000 primedB=00000000
GI8 gp1_09=1
GI8 vram idx=08 primedA=00000000 primedB=00000000
GI8 vram idx=18 primedA=00000000 primedB=00000000
GI8 gp1_09=3
GI8 vram idx=08 primedA=00000000 primedB=00000000
GI8 vram idx=18 primedA=00000000 primedB=00000000
GI8 gp1_09=0
GI8 vram idx=08 primedA=00000000 primedB=00000000
GI8 vram idx=18 primedA=00000000 primedB=00000000
GI8 ctl idx=06 primedA=00054321 primedB=000abcde
GI8 ctl idx=07 primedA=00000002 primedB=00000002
GI8 ctl idx=08 primedA=00000000 primedB=00000000
GI8 ctl idx=09 primedA=00054321 primedB=000abcde
GI8 ctl idx=0a primedA=00054321 primedB=000abcde
GI8 ctl idx=0b primedA=00054321 primedB=000abcde
GI8 ctl idx=0c primedA=00054321 primedB=000abcde
GI8 ctl idx=0d primedA=00054321 primedB=000abcde
GI8 ctl idx=0e primedA=00054321 primedB=000abcde
GI8 ctl idx=0f primedA=00054321 primedB=000abcde
GI8-DONE
ResetGraph:jtb=801e78b8,env=801e7900

gpuinfo8/bench.txt

1089 bytes of TTY text in psx.log

gpuinfo8/when.txt

20261022T2233Z

References