Well that didn't quite go as planned..

A project log for Z80 Reverse-Engineering And Hacking Adventures

What else can I say?

Eric HertzEric Hertz 08/31/2022 at 10:490 Comments

Dave's Pithy DART test program is now a bootloader/BIOS of sorts...

With a little work, it loads a main() function compiled in sdcc.

Previously, the ihexFlasher, which has had a little improvement, and is being used to test my LCD-Grapher (shown above).

It's supposed to display 8 custom characters, the first is "OK", followed by 7 steps up and seven back down.

Since OK is missing, I think somehow the second custom character overwrote the first.

Interestingly, just before I coded this up I happened upon something I never recall seeing previously, about these displays, nor ever had trouble with... Allegedly the BUSY flag actually deactivates after data's written, but 4us *before* the address-increment occurs(?!)

I suppose this could explain it... combined with maybe a few timer-interrupts slowing it down sometimes, and not others...?

Too tired to look into it right now.

Really, I mainly just wanted to see if a graph would look OK if I skipped every-other pixel, so it wouldn't have solid lines broken between every five pixels. Which, I think, would look especially bad if, say, the graph needs to be four pixels per step. I think skipping pixels should work. It'd be two pixels per step, then, and no breaks.


I kinda dig the weird characters that resulted from the glitch... Looks like some ancient script. It always amazes me there can be patterns in a measly 5x7 grid that I haven't seen before.


Oh, the now-pithy ihexFlasher...