I’ve just watched Dave Murrays demo of his “Vera” video card moving some balls round the screen. Initially confused by how it was working, but now understand that it’s to do with the way the colour works in text-mode, so there is a separate “shadow” block of memory that controls the foreground and background colour for each character position.
So in an otherwise idle 10 minutes, for a bit of fun, I paused his video, looked at his code and re-write it to work in BBC Basic and ran it on my Ruby board:
I did it more out of curiosity and a bit of fun than anything else – I’m also experimenting with screen capture software, rather than point a camera at the screen.
the graphics are still generated here by sending commands from the Ruby board via the serial interface to the graphical terminal on my desktop (The ‘terminal’ is a C program using the SDL librarys running under Linux – it listens to the serial port and interprets the usual BBC Micro/Acorn MOS VDU commands)
You can see my source here: https://unicorn.drogon.net/balls.txt it should run on any BBC Micro. (and it’s not the best, but was done quickly – remember the fun part!)
Ps. If anyone knows anything better than “RecordMyDesktop” that runs under Devuan Linux then do let me know, thanks!
Pps. Yes, this is on my new 65816 board – more on that in a later post!