RC 2015/7 – Dances With Pixels #3

Engineer’s Log, Labdate 0728.20. Warp 4.8! We’re getting close.

After a close fight against Murphy I finally won the day: The Commodore CBM 8296 is talking to the HRE via the userport. This small BASIC program demonstrates how the communication is handled on the CBM side. It draws a border around the screen in this order:

(x, y)    0, 0 –> 639, 0 –> 639, 249 –> 0, 249 –> 0, 0


Parts of the program have been squeezed by some methods we used in the early 80th to reduce execution time. These tricks reduced not only the readability of the program but also the runtime from 206 seconds …
… to 159 seconds …
which is still very slow.

If my cell phone cam is able to shoot a video of the program output there will be a final comparison of this pixel by pixel output and the accelerated line output I plan to implement tomorrow.