One of the best courses I took at Texas A&M in the late 80s was a digital logic course. We started with boolean algebra and Karnaugh maps. Next we would draw a schematic for a circuit to implement the logic. After that, we would get out our TTL Data Book, a required textbook for the course, and find the parts we needed to build the circuit. There was a room where you could hand the attendant your parts list, and checkout a breadboard and chips so you could build your circuit. Finally, we would connect the circuit to a scope in the lab and make sure it worked. I loved how the course took us from theory to practical hands-on experience.
I have the same memories of a UNF required computer lab course in 2002 or so. We were required to learn about flip-flops, various other hardware gates, and using truth tables and clocks to form hardware logic.
By the end of the course we had to make a 4-bit breadboard CPU that could handle a couple of operations; a push button acted as the "clock". It was all very simplistic but at the same time I learned an incredible amount about how computer hardware works.
I've got a couple of PDP-8 computers and they are all TTL. Its fun to pull out the three boards that make up the CPU and point out individual things like registers and instruction decoders, but its also something we'll probably never do again.
As an intellectual exercise, when Intel announced their 28nm parts a friend and I tried to estimate if you could get the entire TTL catalog into a single part. Turns out you should be able to, pretty trivially. We imagined a fun (but useless) part with 14, 16, or 24 pins that you could drop into a programmer, pick which chip you wanted and "poof" it would be there (every chip would have every component in it). At that point an FPGA makes more sense though.
Some of the 'classic' parts, like NAND gates and inverters are still pretty useful in teach digital logic concepts, and its fun that folks using Arduinos and other pin limited devices are using shift registers to get more effective pins, but the heyday of discrete logic is well and truly past.
Ive done a fair bit of electronic design over the years (professionally). The classic parts are still going strong. There are even single gate devices now in SMD packages!
Outside the world of computing and mainstream consumer tech I expect to see our friendly TTL devices and op amps etc and even discrete transistors live another 500 years or so. Some problems are quite cheap and simple to solve with them and they're well understood.
(I'm building a laser harp completely out of discretes, logic and analogue components at the moment - not a single microcontroller or CPU in sight. Even hardware MIDI :)
But there are very good alternatives for them, be it low cost mcu's,50 cents fpga's, or even lower-end programmable chips from sillego[1][2]( going down to $0.2/10K + probably $0.1 more for programming - and that's without competition). Those are smaller, more reliable(less soldering) and can do quite complex functions including analog.
So i wouldn't bet on simple gates holding on for 500 years.
Low cost MCUs have FLASH which has a finite life. Same with FPGAs which need to have their brains filled from something.
I worked on a project a few years ago that had a PIC part. They never got the software working right so we looked at the original spec. The entire software could be crunched down to 7 gates and a comparator. So we did a rev2 board with a flip flop and a NAND and a LM358N and there hasn't been a failure since. To be honest with some bastardising to get hysteresis out if a 555 and a couple of transistors would have done as well.
The BOM was £0.09 more expensive but the part never failed in production.
The most interesting thing is that PIC part no longer exists so there is no service option other than replace which costs more down the line.
(This was a watchdog monitor for signalling systems)
Edit: yes I know the 358 isn't a comparator but it was fed just before saturation to get hysteresis avoiding more parts.
You did the design a few years ago, before the silego was a good option.
But for many design , esp in consumer , the silego part would be a good fit because it would work as same as discrete parts,it's manufacturing life and reliability(12 years) would be good enough, and it would be better in other parameters.
And once the consumer market is taken, we might see versions targeted at more demanding applications. But it's not certain.
Please, please, pretty please, document your building of the laser harp and do a write up. That's a thing that I've always wanted to do since I saw JMJ, it's an absolutely incredible concept and a nice DIY write-up would really make my day.
I'll document it when complete and submit to hackaday.com. There have been many dead ends so far so I'll probably just depress myself if I write it up before I'm done :)
My objective is a parts cost of less than £100 and no programming of devices required.
That's basically it yes. Well there's no way to apply aftertouch to a laser harp nor is there velocity so it'll be hard coded velocity (might have a pedal control in future). At the moment it will just sent note on and off down the wire. It does this using three shift registers (74LS165) and some extra bits for start/stop bits.
I've got it sending notes to my Triton so far which is as far as it has got. The harp front end works with one note as I don't have a laser galvanometer at the moment (will build one). I imagine it'll take another 6 months yet at this rate. Plus I keep getting distracted playing with the nice green laser I bought :)
Oh cool, that makes sense. I got a cheap pair of laser galvos off Ebay a while ago (ok long time ago) and built a simple epicycloid generator with them and a Parallax Propeller chip [1]. It was pretty trivial to work with, send it a voltage and poof the galvos moved.
Cool stuff. Much cooler than doing it with a scope and function generators!
I looked at galvos on eBay but I felt like I was cheating. I tried using mirror on a stepper motor shaft initially as a test but the scan rate was abysmal and it was a £3 stepper so it vibrated the bearings loose. Ended up widlerising it. I have a pile of DVD drives ready to be recycled though. They have the shafts, bearings, magnets and coils to make a galvo with. Plus some more lasers to play with. Current galvo ideas are based on:
CPLD's are the step between discrete logic and FPGAs now. You can look at them as exactly what you describe there. They're a great way to implement things when an FPGA is too power hungry or too expensive.
TTL is one of those remarkable achievements that is so blindingly obvious and elegant that you wonder how everyone got along without it. It makes you wonder what sort of similar advances will happen in the next few decades which will make some aspect of the way we do things today look hilariously complicated and outdated.
I still have a copy of a TI TTL Data Book, completely useless these days with the internet, LVCMOS everywhere, all in one microcontrollers and FPGAs, but it's still cool to flip through every so often.
I know, completely useless is an exaggeration. I just find it much more convenient to pull up a searchable/zoomable PDF vs flipping through the book when I do need to check a specs of a 74/54 series chip.
Thanks, and sorry, I missed that point.
My objective was not to shout "hey I flagged" but propose some changes, that have been done.
For what it matters, I unflagged it now.
