Log. 16th November, 2012.

I've got 6309 support into my Perl assembler and disassembler tools, which should make experimentation a bit easier.

http://www.6809.org.uk/dragon/

I've long thought that the TFM instruction would be quite useful for implementing a scrolling shooter, and if you've checked out my demo page you'll know I actually have one of those "in the works" now.

http://www.6809.org.uk/dragon/demo/

So I toyed with it, but it turns out that the way I copy data around, using TFM ends up being *slower*! The reason is that I copy off-screen background data into the "framebuffer" at double height, which requires two copies. Using stacks, you already have a bunch of data in registers for making a second copy. With TFM, it needs to read the data twice.

There are lots of other ways of saving cycles with the 6309 of course - native mode alone speeds up most instructions. I might well have a 6309-specific core program as an option that, say, allows better sound effects.