System/1 Build Log

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An ongoing chronology of System/1's construction, and any other related musings.

28th September, 2014 - Fourgen and concat build

This entry was backdated.

With a return to work looming (and my birthday tomorrow!), and not wanting to lose momentum on the project, I sat down today to look at another board — the one containing what I'm calling the 'four generator' and 'word concatenator' modules. These two parts of the system are pretty trivial; three gates to generate a constant stream of 0x00000004 for one half, and two 74HC164 shift registers and a '157 multiplexer for the other.

In fact, they're trivial enough that it probably wouldn't be totally reckless to skip the breadboard entirely and go straight to soldering up the finished board, but since it'd only take a few minutes to check it out on the breadboard I did so anyway. Everything worked as expected, so then it was straight to the bench to put it on perfboard. Since everything's so simple, it actually takes longer to decide on a chip layout and route the power bus than it does to wire the logic together, but by the end of the afternoon it's all done and tests out happily.

Three boards complete now, and the backplane starts to look a little less daft with them fitted. I guess this thing is taking shape!