How to set the time on your Commodore C64 / C128

- by

Commodore LogoDid you know that the Commodore computers had a built-in clock? It wasn’t an exact science, and it didn’t show the date, but it was able to display a 24hr clock.

It did this by counting how many seconds your machine was switched on, accessible in two variables TI and TI$ (short for TIME).

TI$ is a string value in the format HHMMss, counting seconds. 112347 would mean 11:23am and 47 seconds. TI$ will be 000000 when you switch on the system. You can set it just like any other variable to set the time:

TI$ = "094500"

TI counts the number of 60th seconds since the system was switched on (don’t ask):

print int(ti/60);" seconds since startup"

Both values reset when you reset the system. Like all internal computer clocks it is relatively accurate, but does drift a second or two per day (we don’t notice this on modern systems because those talk to an NTP server once every day and sync themselves).

TI and TI$ are present on the C64, C128, Plus/4 and many other Commodore variants.

If you enjoy my content, please consider supporting me on Ko-fi. In return you can browse this whole site witout any pesky ads! More details here.

Add your voice!

This site uses Akismet to reduce spam. Learn how your comment data is processed.