Hold B to Walk

Wow, I know a whole lot more about ASM than I did 8 months ago.  Gray Shadows, there is something off in your code. The player has to press B once in order for the run speed to take effect. I think the problem is a miscounted byte. 4E2B should be $09, not $08.

(EDIT, July 7th, 2018: There were 2 error. 4E2B should have been 09, and 4E2D should have been 03)

Either way, I re-wrote the whole thing and cleaned it up. It's tested and working. (EDIT: after cleanup, it ended up the same as yours)

Code:

MODIFIED 
$C0/4E21 AD 19 42    LDA $4219   ;Load 2nd byte for controller 1
$C0/4E24 29 80       AND #$80    ;AND for B button only
$C0/4E26 D0 0B       BNE $4E2C   ;Branch if button pressed/held
$C0/4E28 A9 03       LDA #$03    ;Load sprinting walking speed
$C0/4E2A 80 09       BRA $4E2E   ;and branch
$C0/4E31 EA EA       NOP
$C0/4E33 EA EA       NOP
$C0/4E35 EA EA EA    NOP
$C0/4E2C A9 02       LDA #$02    ;Load normal walking speed...
$C0/4E2E 99 75 08    STA $0875,y ;Store walking speed