TIMER interrupts are acknowledged by writes to $1403; this code was also acknowledging them when addressing $1402 in a "non-write" state (read, I guess, but possibly others).
Official documentation makes no mention of acknowledgement other than writes to $1403. Removal of the $1402 acknowledgement seems to fix the issue.
TIMER interrupts are acknowledged by writes to $1403; this code was also acknowledging them when addressing $1402 in a "non-write" state (read, I guess, but possibly others).
Official documentation makes no mention of acknowledgement other than writes to $1403. Removal of the $1402 acknowledgement seems to fix the issue.