Note: the Powershot A3150 IS has the same P-ID (31f1) as the A3100 IS, and in most respects is identical, however it has a slightly different firmware. This means that while it may be possible to attempt to load a CHDK build for the A3100 on the A3150, (the firmware udate function in the menu will see the CHDK update as valid) it probably wont boot, as firmware 1.00D of the A3100 is NOT the same as Firmware 1.00D for the A3150, comparing the strings and dissasembly suggests there would be problems. We should probably therefore treat the two cameras as separate models. It appears that from a CHDK perspective the two models (A3100 and A3150) are identical, and an Alpha version of CHDK for the A3100 ver 1.00D loads and runs perfectly on the A3150 ver 1,00D.