Hey! My documentation efforts are coming along really well, but I need someone to test something on a real Virtual Boy. I’ve attached a brightness test program to this post. If someone could, you know, test it and report back with their observations, that’d be slick.
First things first, I’m still not totally clear on how controller input is supposed to work. This program worked in the emulator I tried it in, but the technique didn’t match up perfectly with what’s in the system manual, so I’m not sure if it will work on a real system.
Anyhoo, when you first boot it, you’ll see something like this:
It’s a red screen with a number on it. The number is the hexadecimal value of the brightness register controlling the rest of the screen. Using up and down on the left d-pad increases it to FF, or decrease it to 00 (respectively).
Okay, so… what this is for…
According to the unit manual, the brightness of pixels works the way brightness of any LED works: it’s directly proportional to how long the LED stays active. LEDs themselves don’t have any brightness capabilities; they’re either on or off. So if you keep them on longer, they seem brighter.
The column table (addresses 0x0003DC00-0x0003DFFF) controls how wide columns of pixels are while drawing to the displays. Since the displays work by beaming a single column of pixels at a vibrating mirror, the angle of the mirror relative to the LEDs constantly changes. In order to maintain a consistent width for all columns in the frame, pixels emitted at a shallower angle need to be a different width than those emitted at a more perpendicular angle.
The manual states that the column table represents column widths in units of 200 nanoseconds, and the brightness registers represent emission periods in units of 50 nanoseconds. Exactly the relationship between them, and the effective maximum brightness of the real system, is what I need some help finding out.
If I’m understanding the document correctly, the maximum brightness for the middle columns of the display (with the default column table) should be where my program shows EE. Advancing the brightness to FF should have a slight increase in brightness on the left and right edges of the screen, but not in the middle.
If I’m misunderstanding the document, I might be way off. I’d test it myself, but I can’t.
So yeah, someone with a FlashBoy, please download brighttest.vb and load ‘er up. If nothing else, let me know when the display gets its brightest.
