How many instructions does [agp.cooper’s] computer have? Just one. How many strip boards does it use? Apparently,
41 five 41-track boards. While being one shy from the answer to life, it is still a lot of boards for a single instruction. The high board count is due to the use of 1970’s vintage ICs including TTL parts, 2114 RAM chips, and 74S571 PROMs.
There are several different architectures for single instruction computers and [agp’s] uses what is technically at TTA (transfer-triggered architecture). That is, the one instruction is a move and the destination or source of the move determines the operation. For example, the Wierd CPU (that’s the name of it) has a P and Q register. If you load those registers and then the ADD register will contain the sum of the two numbers.
There are not many functional units (like ADD), either. There’s a few jumps, some I/O, and you can do a NAND or an ADD operation. We don’t blame him for being economical with such a large number of boards and parts. However, if you make the leap to FPGA, you can build a much more capable one instruction machine. However, we’ve covered many other one instruction wonders, including the breadboardable DUO Compact and the SUBLEQ-OISC.