Month July 2008

board layout

Video System Design

The BMOW video system design is done! Save for that one question about the correct current source setup that I mentioned previously, everything is nailed down to the last detail. I tried to cram in the maximum amount of flexibility…

Current Source Confusion

I’m about ready to call the BMOW video system design officially complete, and hopefully I’ll be posting specs soon. I’ve run into one last snag, however. The UM70C171 palette chip requires a reference current to calibrate the DAC output. The…

Decisions, Decisions

I honestly cannot make up my find about whether to use this salvaged UM70C171 VGA palette chip as part of my video system design. I’ve changed my mind four times already in the past couple of days. I think I’m…

monitor program

Apple II Machine Language Monitor

While waiting for the parts I need for the video system, I ported the machine language monitor from the Apple II ROMs to BMOW. Somehow I’d never gotten around to writing an interactive program to examine and modify memory, which…

RRRGGBB palette sample

Video Palette Setup

I’ve been thinking some more about the best way to set up the palette for BMOW’s video system. It’s the only part of the design that I’m not really happy with. There are a number of different options I’m considering.…