“Invaders” cartridge showing the game variants listed on the cartridge label with one-player games numbered 1,3,5,7,etc. and two-player games numbered 2,4,6,8,etc.

Third in a series of vaguely interesting #Signetics #APVS coding tricks is this one that makes game variant selection a bit easier...

If you look at cartridges, you might notice that single player and two player games often alternate:

A screenshot of Video Pinball running on an APVS machine, showing the four digit score at the bottom of the screen.

Continuing my series of #Signetics #APVS coding tricks - in my ongoing quest to produce content for the most niche audience on the entire Internet - the second trick I’m going to explain is this little nugget:

STRA, r0   $1EC9, r0-
STRA, r0   $1FC9

Code snippet showing the operation EORZ, r0

I’ve been working through some #Signetics 2650 #APVS game disassemblies recently, to see how the code is structured & learn some tricks & techniques from the old masters :)

I thought it might be cool to share a few of them on here & try to explain them in a way that non-programmers can understand.