It’s GID (game in a day) time again! For a change I thought I’d code something for the XGS. I sense this GID is going to be rather painful, just setting things up ready for tomorrow’s start brought its fair share of problems.
Lesson 1 - No accounting for idiocy.
When routing the video/audio output through your digital tv card and you only get black and white check the Crystal. I’d forgot that the last time I used the XGS I’d hooked it up to my TV which supports PAL or NTSC and had been playing around with some of the NTSC only demos. I’d left the 3.57Mhz crystal in the XGS rather than the 4.43Mhz crystal needed for PAL output.
This little voice keeps telling me this is a bad idea. Trying to learn the details of programming a chip such as the SX52 and associated hardware is bad enough, but considering how rusty my asm skills are I’m in for a bumpy ride.
The chances of a successful GID appear to be 3,720 to 1 (about the same as successfully navigating an asteroid field), so I’m lowering my expectation (realy really lowering) and instead doing a PID; pixel in a day. In other words, if I manage to get a pixel up on the screen within the time constraints of this GID I’ll be happy. Anything beyond that is a bonus. I’ve already written code to handle interfacing with the joystick port (see previous blog) so if we can get a pixel up, maybe we can get it moving.
With 4k of direct memory who knows we may even get as far as displaying a sprite, maybe two but lets not get too carried away.
The XGS is hooked up with video/audio routed through my pc to make for easier screen grabs (that is assuming I get as far as displaying anything, otherwise you’re in for some code dumps instead ;) ). For what remains of Friday night and a few hours of Saturday morning I’m going to get comfy with the SX Programming manuals and read over the XGS hardware specs.
That is, after a nice hot cuppa.