Yeah, the hardest parts about this routine were the horizontal zooming and indicating which pixel rows/columns to shift outwards from, and in what order. The horizontal zooming is quite math-based, and took a lot of pacing around my room and thinking to produce and finally get right.

And we don't want to leave grayscale programs stranded, though they'll take a decently sized speed hit: 4 seconds for black and white vs 12 seconds for grayscale. It takes an extra 4 seconds to shift the back buffer and another 4 to update the screen using DispGraph^rr 128 times throughout the process. On 15MHz calculators, this routine should take about 8 seconds.

EDIT: Uploaded a new GIF and source, as I realized I was copying the pictures to the wrong buffers so the grays were reversed.

This is a little weird to explain. This zooms by shifting the screen in parts to each edge. For vertical zooming, it's as simple as copying data from L₆+12 to L₆ and copying from L₆+755 to L₆+767 (reversed) multiple times, each time with a different copy size. Horizontal zooming was a bit tougher and takes up most of the variables and calculations. I multiply a certain number of bytes on the left side of the screen by 2 and divide bytes on the right side by 2, making sure to carry pixels that would be bumped off from byte to byte.

I've just glanced over your early release, and it looks great! I can't wait to see all the things the finished version will include! However, I do have two things to point out:

• This is your call, but it seems like using "//" to indicate comments in code might be a little misleading, as this is not how actual Axe comments work. Perhaps add the comments for each line on the line before it, being delineated like a normal Axe comment with a period?
• I believe "DispGraph^r" in your GrayDemo.8xp example should be "DispGraph^rr."

http://ourl.ca/4832/94254

Random.

For example, I loaded my sprite editor source (I assume it's some sort of reading problem, so a bigger source, in this case almost 15KB, probably means more probability for errors) into archive and compiled it five times, here are the results:

• 67% - ERR: LBL MISSING (and on the first pass?)
• 78% - ERR: BAD SYMBOL
• Success
• 89% - ERR: DUPLICATE
• Success

DispGraph