Commodore 64 Time of Day Clock Alarm Bug Update.

You need to use CIA #2 for TOD. $ddxx. easy fix. Simple to hook the nmi vector.

Seems extra code has been added to this program since the original video, since it no longer smoothly updates in 0.1 second increments. This makes it even more difficult for your program to "catch" the alarm time, without the regular timer interrupt beating you to it - and erasing the evidence. If you POKE 56325,255 before running your program, this will slow down the timer-A frequency, giving your program a greater chance of success. You'll know it's working because the cursor will blink slowly.

Alternatively, if you added a "K) Kill Interrupts" feature to POKE 56333,127 when pressed, I'm pretty sure you'd be able to catch the TOD alarm time consistently. However, you'd need to hit STOP/RESTORE to regain keyboard control afterwards. While this isn't the "solution", it's easy enough to add for experimenting. Set everything up as before, then press K while waiting those final few seconds.

However, I was unaware of the bug in the CIA chip! Good find, that!