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Sacrificing good design

A project log for One-instruction TTL Computer

A breadboard-able computer which uses only a single instruction - MOVE

justin-davisJustin Davis 06/27/2017 at 12:410 Comments

I had thought I would save some gates by using wired-AND connections in some places. However, they are really slow (relatively). The TTL chips can go pretty fast, and if I add wired-ANDs or wired-ORs, it's going to lower the maximum frequency the device can operate. And I feel like it's not good design. I thought I would try to maintain good design practices and not put hacks in there.

I had another idea to use the '374 chips instead of the '996. Those are 8-bit registers with an output enable, but no clock or load enable. So I was thinking I could just AND the clock with the clock enable. While this is logically possible, it's also poor design. One primary rule to digital design is DONT GATE THE CLOCK, and here I'm thinking of violating that rule. I don't think I can do that.

So I'm reversing some of my bad decisions. I'm going to have to reevaluate my design based on this. I may keep the clock system for now since it's only temporary, and I'm only using that for low-speed operation anyway.

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