Johnny's homebuilt 8080 CPU corner (and other stuff, maybe)


XBUS Timer

While trying out stuff I stumbled over one so simple problem that I had to make a new XBUS board to solve it. Overkill, maybe, but as usual, fun.


While this became an issue where when I tried to make a simple interface to an 16x2 LCD module using the XBUS parallel board.


The initializing part of the LCD module requires some waiting times between commands and that made me wonder - If I write a software timing loop, for the 8080, then that timing loop will be different depending on the currect clock speed of the 8080. Not god.


So I set out to solve that problem by constructing a timer in hardware, with its own 10 MHz Xtal oscillator, that could be set to count out a sertain number of clock ticks to eat up time. In the meanwhile the timer would use the /WAIT signal to temporaily halt the 8080 until the time is up.


This timer has never been tested, but as usual, it looks great on paper!


Homebuilt CPUs WebRing

JavaScript by Qirien Dhaela

Join the ring?

To join the Homebuilt CPUs ring, drop Warren a line, mentioning your page's URL. He'll then add it to the list.
You will need to copy this code fragment into your page (or reference it.)
Note: The ring is chartered for projects that include a home-built CPU. It can emulate a commercial part, that′s OK.
But actually using that commercial CPU doesn′t rate. Likewise, the project must have been at least partially built: pure paper designs don′t rate either.
It can be built using any technology you like, from relays to FPGAs.