Flashing Border Colors on the Commodore 128 in Machine Language

In this episode I’ll show you how to create the iconic flashing borders on Commodore machines. Back in the day, when the system was loading, this was a nice way to indicate that the computer is busy doing something rather than being dead.

I’ll show you the principle both in BASIC and in Machine Language on the C128. The VIC-II chip is the same on the C64 though, so this will also work on the Commodore 64.

The same approach can be used on the Plus/4, however the addresses for the border and background colours are different (decimal 65305, or hex $FF19).

The VIC-20 is another story, as the border and background colour are changed using the same address (decimal 36879, or hex $900F). This link may help though: http://www.sleepingelephant.com/ipw-web/bulletin/bb/viewtopic.php?t=5905

As always, enjoy 🙂

Watch the full course in one convenient playlist:
Catch this episode on my Commodore Podcast:

Jay is the CEO and founder of WP Hosting, a boutique style managed WordPress hosting and support service. He has been working with Plesk since version 9 and is a qualified Parallels Automation Professional. In his spare time he likes to develop iOS apps and WordPress plugins, or draw on tablet devices. He blogs about his coding journey at http://wpguru.co.uk and http://pinkstone.co.uk.

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