In which Techie writes a late-night techblog about CPU registers · 7:42am Nov 11th, 2019
SO.
The 74ls273 is a pretty neat device. 8-bit flipflops with an output enable and a clear contents signal. All in all it's pretty nice. Only problem? No input enable. You throw a hunk of data at it and it'll swallow it up even if you don't want it to.
The solution? the 74ls173. The '173 has both input and output enable pins, plus a clear contents pin. The only problem? One, it's only 4 bits, so I've gotta double them up.
Two? I'm reasonably sure that all three '173 chips I ordered are DOA on account of the fact that even after testing them against both my own designs and known-working ones posted by Ben Eater, I get absolutely no data out, even when the output enable pins are enabled. So I have 0 idea of whether or not my design even works in the first place.
One possible solution to both? Enter the 73ls377. It's pretty much a hybrid between the '173 and '273 in that it's 8 bits, but it's got an input enable pin. It doesn't have any output enable, but I don't need one given what I'm using it with. However, one drawback is that it has no clear contents pin, which means I'd have to make a workaround for it. (In all honesty, it'd probably just be a read-only register that's completely zeroed-out that I'd perform a register transfer out of.)
Anyway, end rant. I'm gonna do some more testing of my '173 chips to see if they really are dead or not and then start making designs for a '377 based register.
Congratulations, you just fried my brain before it even fully woke up
Reminds me of an old quote from Doctor Who:
(Roughly this is how it goes)
[Rose and Sarah Jane meet]
"Does he still do that thing where he talks at 500 miles an hour, you say "Huh?", and he looks at you as if you spilled soup on your shirt?"