Wasn't expecting the internals to be like that. I thought it would be some sort of gated ring counter. It does explain the odd pinout though. That was one of my first chips alongside the 555 and LM3909 LED flasher.

Thanks for listening to us and doing the explanation of the structures at silicon level

At 0:07, you say September ‘83, but that’s actually the 9th week of ‘83, so March(?)

cool chip nixie tester, universal counter etc

Thank you. I wondered since about 25 years that I’m into electronics why this chip has that strange pinout.

I can't believe how far we've come from then to now it's nuts.

If you look closely there is definitely a bond pad troll in that IC

@stevenflogerzi1955

4 жыл бұрын

It looks like the bond wire came off of pin 5.

@lazerusmfh

4 жыл бұрын

Steven Flogerzi it also has a smug look in the first shot :D

Helpful video 👍 I like it

Would love to see a video on the 74HC164 8 bit shift register

@jercos

3 жыл бұрын

A 74LS164 plus some logic is an LFSR, equivalent to a 255-step counter with an unusual order. Fold that logic with a wavetable into an EPROM, add an R-2R ladder DAC, and you should be able to generate arbitrary waveforms accurate to at least 7-bit precision (presuming the LFSR is robbing a bit from an 8-bit EPROM) with 2 off-the-shelf ICs. Adding another shift register and using a large EPROM scales as far as your resistor tolerances+clock speed allow, and extra address lines can select between waveforms for a full-featured function generator. A PIC or AVR could also do the same thing in one self-contained chip for less than the current cost of a 27C256, but where's the fun in that?

did you ever decap something like a "modern" processor ? If I can get my hands on the fuming nitric acid stuff I will try decapping myself, for most dead components. I have a small repair business (mostly test and calibration gear) and I am often curious what went wrong inside a component. I had a dead transistor (TO220) a few years back, and that was already replaced rather recent befor. I decapped it together with an original on a mill and found out the die of the newest one was about 1/3rd of and the metal plate was a lot thinner. Both where the same brand.

Excellent video. Audio is a little rough for my old ears.

Still a very handy part !ing similar.

Could you "fix" the pinout in the bonding?

@uzmeyer1752

4 жыл бұрын

theoretically yes but you generally dont want to bond across the chip as well as keep the bonds as short as possible. Back when that chip was first made they probaply didn't have machines that could bond across wires (even today its rare, but sometimes used for extremely high pad counts with multiple rows) and if they had todays tech they would have just added extra layers to the die and fix it there

Almost 40 years old, eh? I will have you know that people born in 1983 are only 36, which is practically late twenties :P

@AnonyDave

4 жыл бұрын

I'm 6 months older than that chip, and I think it's in better condition than I am 🙃

Nice video, never imagined it would look like that on the inside. Tip: get a better microphone, your voice gets a bit too boomy and unclear.

Why do some of the inverters have an inverted input and others an inverted output?

@station240

4 жыл бұрын

It's a concept called "negative logic" as opposed to "positive logic" which we all know. One denotes it creates a negative output, expects a positive input, the other creates a positive output, expects a negative input. For a simple inverter, it doesn't make any difference, however the way it's drawn shows the negative output to negative input cancel out. So you can redraw it as an AND gate wired to a buffer, without changing the logic at all. For more complex devices, the negative input can change how the chip functions. The 74xx123 is one basic logic gate with negative inputs, 80's/90's era RAM/ROM also has them.

@TomStorey96

4 жыл бұрын

@@station240 interesting. Never thought of it like that before. Do you happen to know why some schematics have, e.g. AND gates drawn as NOR with inverted inputs, or is it much the same reason (although it makes it a bit of a headache to read)?

Your videos are great. You really need to sort your audio out though, way too muffled.