As an adventure in computer history, [Len] built up a clock. The Z80 Micro TV Clock brings together a homebrew computer and three Micro TVs into a rather large timepiece.
The computer powering the clock runs the CP/M operating system. This OS was eventually released as open source software, and a variety of homebrew computer projects have implemented it. This clock is based on an existing breadboard CP/M machine, which includes schematics and software.
With an OS running, [Len] got a text editor and C compiler working. Now custom software could be written for the device. Software was written to interact with a Maxim DS12885 Real Time Clock, which keeps the time, and to output the time to the display controllers.
The Micro TVs in this build are Sony Watchman displays featuring a 2″ CRT. The devices had no video input port, so [Len] ripped them open and started poking around. The NTSC signal was found by probing the board and looking for the right waveform.
To drive the TVs from CP/M, a custom video driver was built. This uses three relatively modern ATmega328P microcontrollers and the arduino-tvout library. All of these components are brought together on a stand made from wood and copper tubing, making it a functional as a desk top clock
There’s something about the strange anachronistic combination of technologies that appeals to me. CP/M, Arduino, old analog TVs, new ATmega processors, all held together with a frame soldered out of copper plumbing pipes and fittings!
It’s certainly not the most practical or simple method of building a clock, but if you have to ask “why”, I suspect you’re missing the point.
A fine blend of vintage and modern tech!
this is art and dedication!
This is a pretty cool build but I can’t help but think that you could do the entire project with a single Parallax Propeller, emulating the Z80 to run CP/M, and generating all three TV signals with nothing outside the chip but some external RAM and a few resistors.
Then what would be the point of sticking with Z80 architecture or running CP/M? Or even driving these televisions with it? At that point, it would be “easier” in terms of parts and labor to just hook a propeller chip to a set of OLED displays. Or an arduino, for that matter.
The thing that’s impressive and elegant about this thing isn’t that it’s a clock, or even that it can run CP/M. What’s impressive is that this is a full computer system that he soldered together from scratch, and that it not only works, but that it is actually capable of running a popular operating system to boot. He didn’t just grab a computer-on-a-chip like a microcontroller, he build the computer from scratch and not only dos it run, but it even fits together into an aesthetically pleasing (retro) form factor.
Exactly, its a computer that runs a vintage desktop operating system built with some chips on a freaking breadboard! Vintage computing doesn’t get any better than this!
Well getting a Z80 to run isn’t much harder than using a microcontroller if you use static RAM. I wasn’t dissing the project, but in a sense it’s really a couple of projects glued together; using the vintage Micro TV’s is kind of a separate thing from hacking the Z80 to life, and while the result is cool neither half of the project seems like the world’s best fit for the other.
Even better, you could do the entire project with a cheap clock.