Sunday, 23 July 2017

IIC, or not IIC, that is the question:

Whether 'tis nobler in the mind to suffer
The Apple II hires video memory map,

Due to an SOS call from my wife whilst I was en-route to WozFest (car trouble) I ended up missing the brief link-up with KFest and people had well and truly broken off into small groups to work on their own projects by the time I arrived, which meant I didn't get the chance to see it running on real hardware.

I did get a chance to do a little more work on it though (despite heckling from the Peanut Gallery - you know who you are) and have now got pixel-shifted graphics rendering. Although somewhat hampered by the flickering graphics, on close inspection it is definitely animating more smoothly now.

I also decided to go down the path of so-called compiled sprites, reasoning that it wouldn't be very difficult to write a C program to parse my ASM bitmap data file to produce the requisite code. I've got one or two minor optimisations to effect first, and then I'll give it a spin. If that doesn't make a marked improvement, I'll be at a bit of a loss in terms of how to proceed further. As a first-pass I'll opt not to use stack-blasting and see where that gets me.

After chatting to a few learned fellow attendees at WOzFest it became apparent that the 4MHz IIC+ would be another good candidate for a port - even more capable than the IIGS in fact - with a faster CPU (same video memory bandwidth) but with a monochrome graphics mode meaning only 1/4 of the graphics data to push around. I'm fast running out of excuses to keep avoiding the legacy Apple II hires video display...

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