Sequencing & Control Test

It’s finally time to give all the cards created so far a test so I can check everything works together as expected. This represents quite a bit of a milestone as the computer can now perform a single ALU, SETAB or MOV-8 instruction. This means a user can technically run a program by entering and running each instruction in turn and although the computer is still a long way from completion with this latest round of functionality it’s a lot more usable than before.

Viewed from the front the computer now looks like this:

Relay Computer (front view)

I’ve put together a new video to mark this construction milestone which gives an overview of what’s changed since the last milestone, a tour of the computer as it currently stands and finally a demonstration of running a program through the computer.

So, with a line drawn under what’s been built so far it’s time to look at what comes next. There’s quite a few different ways to go from here but I’d like to concentrate on getting the computer to run a full program all by itself.

Unfortunately there’s quite a bit involved in implementing that simple statement of ‘all by itself’. The first thing the computer will need is some memory so that each line of the program can be stored. Once that’s in place it’ll then need a program counter so that the current position in the program can be tracked and it’ll also need an incrementer to move the program counter on following each instruction.

As before, I’ll start with covering the design of each of the required upcoming cards (memory, program counter and incrementer) and then move on to construction and finally that’ll get the computer to the next milestone where everything can be tested together. Here we go again …

Published May 24, 2016