Mystery hardware register $f71d
Please download pv2devkit if you don't have it and then assemble and run this code. .ORG $90 TOP: LDI R0,#$01 ; value used to reset watchdog timer STA R0,$f716 ; - Reset watchdog timer STA R0,$f71d ; reset mystery register to $01 LDA R0,$f71d ; check mystery register BNZ BEEP ; beep if it is not zero JMP TOP ; else don't beep BEEP: LDI R4,#$04 ;duration of beep LDI R2,#$80 ;pitch of beep PLAY: STA R4,$f700 STA R2,$f701 LDI R0,#$01 ;beep mode instead of timer mode STA R0,$f702 LABEL: LDA R0,$f703 BNZ LABEL ;wait for beep to complete JMP TOP 1. Run it without batteries in your camera. 2. Run it with batteries in your camera. 3. Do 1 and then put in batteries while it is running. 4. Do 2 and then take the batteries out while it is running. 6. Try anything else you dream up to figure out what the exact purpose of this hardware register is. 7. Post your guess as to what this register is used for. 8. If you work for Pure Digital or Smal Camera Technologies or a related company or for whatever reason you KNOW what it does already, then skip 1-7 and post the authoritative answer with a spoiler notice starting your post so all those who want to post their guess before seeing the answer can do so. Another thing you might try is changing BNZ BEEP to BRZ BEEP and notice the difference.

Re: Mystery hardware register $f71d
Has anyone had a chance to try this? I'm going to have to re-run it myself to refresh my memory of what it may seem to be doing. In the firmware it is most often set to 1 and then checked until it is not zero. It is also seen occasionally where it is checked without first setting it to one. Please download pv2devkit if you don't have it and then assemble and run this code. .ORG $90 TOP: LDI R0,#$01 ; value used to reset watchdog timer STA R0,$f716 ; - Reset watchdog timer STA R0,$f71d ; reset mystery register to $01 LDA R0,$f71d ; check mystery register BNZ BEEP ; beep if it is not zero JMP TOP ; else don't beep BEEP: LDI R4,#$04 ;duration of beep LDI R2,#$80 ;pitch of beep PLAY: STA R4,$f700 STA R2,$f701 LDI R0,#$01 ;beep mode instead of timer mode STA R0,$f702 LABEL: LDA R0,$f703 BNZ LABEL ;wait for beep to complete JMP TOP 1. Run it without batteries in your camera. 2. Run it with batteries in your camera. 3. Do 1 and then put in batteries while it is running. 4. Do 2 and then take the batteries out while it is running. 6. Try anything else you dream up to figure out what the exact purpose of this hardware register is. 7. Post your guess as to what this register is used for. 8. If you work for Pure Digital or Smal Camera Technologies or a related company or for whatever reason you KNOW what it does already, then skip 1-7 and post the authoritative answer with a spoiler notice starting your post so all those who want to post their guess before seeing the answer can do so. Another thing you might try is changing BNZ BEEP to BRZ BEEP and notice the difference.