chaplet systems halikan

A few weeks back, my son was digging around my parent’s attic and found an old laptop that I picked up in high school. The laptop is a Chaplet Systems Halikan NBA486. I found it in one of the cabinets in my electronics class and it was already almost a decade old, so my teacher said I could keep it. It didn’t have a battery or a power adapter, so I was never able to do anything with it, but when my son brought it home, I told him we’d try to get it working.

homebrew z80 computer

A while back I found the RC2014 project which is a modular z80 computer. I’ve been wanting to play around with the z80 and this looked like a good place to start considering I already had most of the parts. The RC2014 is designed around modules that plug into a back plane. There are many modules available, most of which have published schematics, so it was fairly easy to get started.

atari 7800

Over the last few weeks, I’ve picked up several atari game consoles like the 2600, 2600 jr, and a 7800. I tried hooking them up via RF, but the quality is terrible on my TVs, so I went looking for composite mods. I started with the 2600 junior. I built a single transistor amplifier and wired it in, but I was getting some strange behavior with the video. I then tried a more elaborate multi-amplifier circuit, but saw the same issues.

commodore 128

Another recent addition to the collection is a Commodore 128. I picked it up at a local estate sale with a 1571 disk drive, another Commodore 64, and some cartridges and accessories. When I first brought it home, it was filthy. I decided to clean it up first before I tested anything. The power supply had some little plastic caps that filled the screw holes. I used a bit of hot glue on the end of a small screwdriver to pull the caps out.

atari 800xl

I finally got around to working on the atari 800xl that I mentioned back in October. This machine has been a nightmare. To start, it would power up to a slightly reddish black screen. I couldn’t find any good info online about this particular ailment, so I decided to just start swapping chips between the atari 800xl and the 600xl that I have. I’m not sure if the 600xl is in working order.

cosmac elf

The next step in my homebrew computer adventures is the Cosmac Elf. The Cosmac Elf was a DIY computer that appeared in Popular Electronics in 1976 and 1977 using the RCA 1802 microprocessor. The schematics that I used are here: ELF Schematic 1 ELF Schematic 2 Other good resources can be found here: http://www.sunrise-ev.com/vcf-elf.htm http://www.cosmacelf.com/ I was able to find all of the parts except for the TIL311 displays. Well, I could find them, but the cheapest I saw was $30 per display, so I ended up using regular 7-segment displays with an arduino driving them.