Notes on Video
The high-level design of the BMOW video system is mostly complete now, but is scattered across eight pages of scrawled notes and the inside of my head. It’s proving to be a complex beast, and there are still many smaller…
Video Tests
My loftiest of stretch goals for BMOW is to build a primitive video circuit, and connect the machine to a standard VGA monitor. To that end, I did some prototyping experiments on a breadboard recently to experiment with video generation.…
Multitasking Success
After a LOT of fiddling, I finally pulled off a successful multitasking demo. It’s not the most exciting thing in the world to watch, but once you understand what’s happening, you’ll appreciate the nerd factor. The photo below shows BMOW…
Robo-Flower
I recently took a break from BMOW’s multi-tasking support to work on something completely different. (Actually, I have a multi-tasking demo working in the simultator, but it doesn’t work on the real hardware yet.) The “something different” was a robo-flower:…
User Mode Programs
I made a little progress this week on separating what I hope will eventually become the operating system software from everything else. Up until now, all the test programs I’ve written have essentially been the operating system, or part of…
Clocks and Interrupts
Today I moved a few steps closer to completion of the initial hardware design. First, I verified that BMOW’s interrupt mechanism actually works. My previous experiments with the keyboard and USB employed busy loops to continuously poll for new values.…
Small C
I’ve begun looking more deeply into the “Small C” compiler that Bill mentioned. It looks very cool, yet also wildly inefficient, which is about what I expected. With some more effort, I think I could get a working C compiler…
Keyboard Kaos
After another round of bug fixing and the creation of a BMOW keyboard driver, the keyboard works! And it truly works this time: pressing the A key shows “a” on the LCD, and pressing SHIFT and the A key shows…
Microcode Cleanup
I’ve gotten a bit derailed from the task of writing the keyboard scan code handler, into the bigger issue of how device drivers like this should work in general in BMOW. That’s led me to an entirely different question of…
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