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Chip availability (oh TTL...)

A project log for One-instruction TTL Computer

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

justin-davisJustin Davis 05/12/2017 at 18:560 Comments

I started thinking about how I'm going to implement the chip version of the project. I'm leaning toward solderless breadboard at first. And then maybe a board layout. So I started looking for chips to order online and ran into problems.

I've been able to find the chips I expected to use, but they are upwards of $60+ per chip. I guess I didn't check the price - only if they were available. And I wasn't expecting it. SOOO I may have to bend my rules a little. I've looked for parts which are drop in replacements even if they aren't active chips. So the spirit of the goal is intact if not the letter.

However, even those chips are little pricey. The register chips are $6 each, so I may replace them with a cheaper version where I don't need all the functionality. The 74LS374 Octal FF can work in a lot of places just fine and is only 79 cents. I believe I need 8 of these, so it's probably worth it to drop down when I don't need the extra functionality.

The 8-bit counters are $8.25. So I may drop down to the 74LS161 4-bit counters at 79 cents. I'll just need two for each 8-bit version which ups my chip count. So $16.50 for two or $3.16 for four. But there's only two of these, so it might be worthwhile to go with the more expensive version.

But at least I can find all the parts I need in some form or another. I'll have to make a mini-roadmap to build this up in small sections so I can debug and verify as I go.

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