Wednesday, April 5, 2017

Testing on hardware

Everytime I title a post like that, it's never good news.

We moved across town, which primarily means that I've spent more time fixing up an old house (to sell) and a new house (to live in) than I have programming for fun.  But I also had space to set up a nice desk space for writing/testing my games, including my NES and Atari attached to an old little tube TV (thanks, Jake!)

After hours of frustrating with faulty Compact Flash cards (remember those?), I finally got my PowerPak working, so now I can test my game on the real Nintendo! (as well as play all my NES games without fighting with dirty contacts every time!)

Well, as usual, it didn't go well at first.  Spacey McRacey was a jumbled mess of flickering as it scrolled. It bounced all over the place.

With some advice from the fine folks at, I had a number of things to try, but none of them worked.  BUT simplifying things by disabling my split-screen scrolling (the status bar at the top is locked into place by having a scroll split at it), and everything worked.

So I went back and tightened up the timing of my split screen scroll.  The NES PPU has some weird quirks, where underlying registers change automatically during rendering, so it's quite possible that I was taking too long, and things changed out from under me in the middle of setting up my split-screen scroll.  So optimizing the timing of the scroll actually ended up solving the issue.  WHEW, that only took about an hour (which is about 4 hours less than the time I've spent so far trying to fix the bad wiring in my house that fried my TV and desktop computer)

There's still one new issue that appeared on hardware that I need to fix, with the title screen getting corrupted, but I think I know what's going on there.

And here I thought I was done. Oops.

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