So, I started right in on this project and didn't really explain much. You can't blame me. That robot chassis had to be built immediately!
My end goal is a line following robot that uses a MC14500B 1-bit processor from 1977 to control it. Now, "1-bit" sounds absurd, but that just refers to the size of the data that it can do operations on. It still uses 4 bit wide instructions, and the address bus and program counter could really be as wide as you want as that is external to the processor.
I won't go into a huge amount of detail on the processeor as there is a lot of good reading available about it:
- Wikipedia
- Motorola's MC14500B ICU Handbook
- Ken Shirriff's epic reverse engineering effort
- Usagi Electric's YouTube Channel where he makes a tube computer modeled on the MC14500B
- av-retro's MC14500B line-following robot from RC2022/10, my inspiration for this project
For my purposes, I will be using an 8-bit wide ROM of some sort. As the instructions are 4 bits wide, that leaves the other 4 bits to do fun stuff like select the input or output registers. Those 4 address bits would give us (2^4) 16 possible 1 bit inputs or outputs to choose from and process. Since I don't need that many for my simple robot, and the standard ICs I am using use 3 address bits, and I am tight on space, I will end up with 8 possible I/O registers to choose from. Four of those will probably be directly connected to each other, providing a tiny amount of memory. For the most part, I will just be copying the Minimal ICU system in the Handbook:
So nothing really revolutionary here. But, I will be adding some additional spooky sounds, and I think I will try to add a fan to make the ghost pop up like one of those inflatable wacky waving arm flailing tube man things! It sounds pretty ridiculous, but so be it!
Just working on the gopher site tonight. Didn't have time to cut off that motor mount screw before the kids went to bed.
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