Tuesday, 3 May 2016

Space Invaders in 6809. Now with added bugs.

At lunchtime today I dug in and managed to finish porting the remaining 8080 code to 6809.

There are a number of bugs that make the game less playable than it was in the past, but I'm hoping there's nothing too difficult to track down. That said, it'll probably take a few nights of debugging to get it running 100% correctly.

In the process I'll clean up a few 'nasty' bits of code to make it a bit more relocatable on the Coco; as-is the data - both in ROM and in RAM - is byte-for-byte aligned with the original. That's something that I won't be able to preserve when I rotate the graphics, so I need to make sure it's not going to break when it's not aligned.

Hopefully the next update will be reporting a flawless port!

UPDATE: Well not flawless yet, but much improved. If I absolutely had to guess, I'd say about a half-dozen more bugs to find and fix (I can count 4 off the top of my head) - the game is so simple that most of the bugs should show themselves quite readily.

Fixed a few bugs in the invaders firing and high score calculations. The game crashes now; I suspect at the point that the saucer is to appear (I've yet to see it!)

Added dipswitches - currently build options - but they do work. I'll likely add them to the Coco3 splash screen before the game is launched. Also added the TILT input, which can be initiated on the Coco3 using the <CTRL><BREAK> keyboard combination - to be used for rage-quitting!

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