As in all good projects, I decided to start with the final display, that is the graphics. I was able to locate the BBC microcomputer user guide in my loft. My guide is dated 1982 and acknowledges, among others, Richard Russell who wrote the BBCSDE interface that I decided to use in the previous post. The user guide contains a list of BBC BASIC commands and covers basic graphics with some sample programs including a classic Moon Lander game. I started by flicking through the book.
It didn’t take to long to write a simple BASIC code that would plot the grid and display Pentomino pieces in different colours. The code itself is quite useless, but it was a good start and will come in handy for displaying solutions (assuming I find any) and debugging algorithms that aim to fit the pieces together. I also found that the Teletext graphics mode contains several of the Pentomino pieces and that it is possible to define more as characters. An algorithm could probably be made directly using graphics commands and direct memory addressing or just based on the colours. However I decided against that approach since it would be difficult to port to other codes in the future.