http://www.stevechamberlin.com/cpu An 8-bit home-built CPU Wed, 15 Oct 2008 03:08:19 +0000 http://backend.userland.com/rss092 en I've made some additions to the ROM-based boot loader, so BMOW now has a proper boot logo paired with cool yet useless system diagnostics. All it needs now is a groovy start-up sound, and it will be a proper retro-80's wanna-be machine! Power it up, or hit the reset button, ... http://www.stevechamberlin.com/cpu/2008/10/14/boot-logo-needed/ I've reached an exciting point in the evolution of BMOW. All of the individual bits of technology that I've built are now coming together, and rather than a proof-of-concept of keyboard or USB or video functions, I actually have a real computer! I took some time this week to put ... http://www.stevechamberlin.com/cpu/2008/10/11/putting-it-all-together/ Following my experience with the video system, I decided to create a boot loader. It's a little surprising that I never did this before, actually. While working on the video, after every tiny change to the video software, I had to reprogram the BMOW main ROM and stick it back ... http://www.stevechamberlin.com/cpu/2008/10/02/boot-loader/ Here's the promised better example of BMOW's video capabilities. It demonstrates text with different foreground and background colors, and the use of text and graphics on the same screen. By using two bytes per line to control the video mode instead of to encode pixel data, the video display becomes much ... http://www.stevechamberlin.com/cpu/2008/09/20/mixed-mode-video/ Some good news on the video front: by modifying the pixel clock and playing with my LCD monitor calibration, video quality is dramatically improved. The pixel stretching stemming from my non-standard 512 pixel horizontal resolution is gone, and even the light/dark vertical noise bands are almost completely gone. Interestingly, it ... http://www.stevechamberlin.com/cpu/2008/09/15/25175-mhz/ BMOW is now text-enabled! I stole an 8x16 bitmapped font from the X11 font set, programmed it into my character ROM, and now I can do this: OK, it would be a more impressive demo if I actually wrote some specific text to the screen, instead of displaying garbage memory as ... http://www.stevechamberlin.com/cpu/2008/09/13/text-generation/ Yarrgh, thar be pixels! BMOW's video system still has many minor issues to resolve, but the critical pieces are all working now. I can set up a video mode, poke bytes into video memory, and see pixels on the screen. I can even display digital photos. It's almost like a real ... http://www.stevechamberlin.com/cpu/2008/09/07/video-demo/ Video works! Er, sort of. After fixing the HYSNC problem, I experimented with the palette chip, just to prove it was working. With a few bytes' worth of changes, I was able to turn everything red. The monitor was still confused about the resolution, though, thinking it was 1152x864 when it ... http://www.stevechamberlin.com/cpu/2008/08/30/video-bringup-part-2/ After an eternity of procrastination and wire-wrapping, I finally finished BMOW's video subsystem. Well, not quite finished really: the character generator is still missing, but the all the hardware is there to support the pure graphics modes. It's about time! With anticipation I flipped the power switch and was greeted with: ... http://www.stevechamberlin.com/cpu/2008/08/27/video-bringup-part-1/ Yesterday I found an interesting advertisement. A Berkeley student was moving out of the area, and was selling his entire collection of electronics and robotics parts for $50. Of course I had to pick it up, so I'm now the proud owner of more random electronics stuff than you can ... http://www.stevechamberlin.com/cpu/2008/08/20/loads-o-random-stuff/