So this is something that I have wanted to do for a while now and I realize that it is totally pointless and a waste of time and all that, but hear me out.
>> modern CPU's are mind-numbingly complex, containing billions of transistors.
>> ancient CPU's are still mind-numbingly complex, but might only have a few thousand transistors.
>> the Intel 4004 only had 2300. Granted, it was an 8-bit CPU that cant really do anything by todays standards. Even CPU's like the atmel atmega 328 18-bit cpu used in the arduino uno is far superior to the 4004. Heck, even the atmega 8, the 8-bit version (used in other, less powerful arduino boards) is far more advanced than the 4004.
>> a transistor can be constructed with two LED's with their polarity's facing in opposite directions.
>> In theory, the intel 4004 could be made with a mere 4,600 LED's, a bunch of header cables, and a TON of breadboards.
>> I want to build a CPU out of LED's. I want it to actually be able to run programs. The 4004 would be easy to do (assuming you used IC chips for the 4 supporting chips needed for it to run) but it is VERY limited in what it can do. If we made an atmega 8 out of LED's and other components below the logic gate level, it could actually run stuff that people use today for arduino programs.
>> using LED's instead of transistors would double the number of components needed, but you could see the individual LED's flash on and off, so that would be cool.
>> Now all I need is a reason to do this that is convincing enough to get people to help, people to help, a full schematic of the atmega 8 or equivialent CPU, an unlimited supply of LED's, and a shit ton of breadboards.
>> Im thinking I have discovered an awesome graduate project for a physics major and CS minor like myself...
>>53789394
the 328 is a 16 bit, not 18 bit. typo
It's 8-bit, it's basically a fancy version of the Atmega8
I'm waiting for the news report of some faggot setting his house on fire cuz he tried to fire a few thousand leds with a 220W cable
LEDs have about a 2 to 4 volt voltage drop using 4600 of these obviously not in serial would require something like 2000 volts.
Also can you really make a transistor from two LEDs, never heard of that and that's not really how NPN or PNP technology works.
>>53789394
How would you go about cooling something that large? I'm not saying it'd be impossible, I actually think it sounds bretty cool.
>>53789394
lol
>>original postaroo
>>53789394
Yeah that's not going to work.
>>53789570
yes, Iv done it. a transistor is just 2 diodes sandwitched together, an LED is just a diode that happens to emit light as a side effect
>>53789578
This would not be a small device. It would probably take up a large room of some sort. Could use the buildings AC and have fans wherever hot spots developed. Remember that these thing produce heat because they have a LOT of components packed into a small space.
>>53789570
hadnt thought of the voltage requierment to be honest... although they would be in serial. Would be a lot easier if they were in parallel because then all you would need is a really nice gaming PSU or a server PSU to crank amps...
>>53789512
this. The AtMega329 is 8 bit
it is in the next "generation" though and so has a lot of extra features
>>53789394
yes, you CAN build this, but may take years, and the max speed you will ever reach will be miserable and again will not be able to run "real programs"
>>53789996
why would the max speed be so bad?
Again, I realize that it isnt going to be practical, but you would be able to run simple stuff on it...
>>53790009
note the speed of the modern processor. It is ~4GHz. This has been achieved by two things
- faster transistor switching speeds
- smaller interlinks
Using LEDs fight back against both those points. LEDs are big and so interlinks are longer which slow it down, and LEDs are not designed to switch quickly and so will be slower.
>>53789959
I can't pretend to be an expert on the subject but a few years ago I took a class on semiconductor physics and two diodes is definitely different from one transistor. The base needs to be short enough for the electrons hole pairs to be able to reach each other, maybe with certain LEDs.
This article explains it well:
http://electronics.stackexchange.com/questions/78366/why-cant-two-series-connected-diodes-act-as-a-bjt
>>53790057
more on the interlinks
- capacitance is higher, so takes longer for a voltage change when you "switch on"
this is all my knowledge on this right now. I can design processors, but not implement them (CompEngineer not an Electrical)
>>53789394
>a transistor can be constructed with two LED's with their polarity's facing in opposite directions.
No. No you unfortunately can't do this and I don't know who the hell told you this.
>>53789394
Get a life you faggot
>>53789411
328 is 8 bit
>>53789959
>yes, Iv done it. a transistor is just 2 diodes sandwitched together, an LED is just a diode that happens to emit light as a side effect
Sorry, but no.
http://electronics.stackexchange.com/questions/78366/why-cant-two-series-connected-diodes-act-as-a-bjt
>>53790147
I like how on a "technology" board almost nobody knew this literal EE 101 stuff.
>>53790105
Yes, you can, Iv done it.
>>53790147
want pictures? Wont prove anything because you cant actually see it work, but it did work.
/sci/ might serve you better, assuming you haven't already posted there.
>>53790437
here, have a schematic.
The third LED is an indicator to see that it works. The switch is used to open and close the transistor. Keep in mind that 5V will blow up most LED's, the ones I was using are somewhat unusual in that respect as they are ultra brights. (the red ones in the picture are considered "normal" output by comparison.
>>53790605
seriously, if you dont think it works, build this and see for yourself. its acutally pretty cool
>>53789394
A computer that actually blinks according to the data it's processing sounds fuckawesome.
I would suggest doing it in an SMD form factor. Don't attempt a through-hole system, because that would be kind of large.
>>53789394
>make unnecessarily complicated abomination that uses lights instead of proper components just for the hell of it
>it's still smaller, more efficient and produces less heat than any computer of more than 40 years in the past
>>53790057
>>53790098
So he'd need to limit the clockspeed?
What would the rough ballpark be? Hertz, Kilohertz?
>>53790605
>The switch
What, you want to use a physical switch?
Isn't that kinda the exact opposite of what a transistor is used for?
>>53790903
microhertz
>>53789989
Sure 97A seams reasonable just don't forget the gauge 3 wire and you should be set :^)
I would love to see this complete IRL
>>53789394
This is the sort of project you could make an awesome youtube video demonstrating.
You might make something simpler than a 4004 even. Make a 4 bit processor or something. Bonus points if you design it yourself, though then you have to write your own assembler and such. Connect it up to some generic SRAM/PSRAM chips for storage because building thousands upon thousands of RAM cells is boring as fuck. Or if you want to go full on retro, get a bunch of ferrite rings and weave some core RAM.
As for software, maybe aim to make a 4-function calculator with it, and expand it to be more of a scientific calculator.
>>53790903
max i would guess (Really a guess) is like 25K hertz
there was a project of a guy building a system out of discrete transistors and i think he didn't get past about 20. So it is a challenge
>mind numbingly complex
What are: Hardware descriptive languages, VLSI techniques. Using abstractions you can make it a lot simpler.
As an EE it boggles my mind how far programmers seem to get away from hardware.
>>53791112
Remember that the visual effect wouldn't work if the framerate of the LEDs is too high.
Something on the order of 60 Hertz is easier to grasp for human eyes.
>>53791154
>Using abstractions you can make it a lot simpler.
Well, duh.
You can also call it a CPU and be done with it.
>>53789394
You can do that, but it would be a lot more feasible to make a CPU in a hardware description language.
When you have done that, you could build the thing.
This way you can easily improve your design when you down the road wants to implement new cool features.
>>53789989
If you wouldn't set everything on fire, sure, it might work.
>>53789394
Diodes and transistors are very different, but that's not too say you couldn't build a large scale semiconductor chip out of lots and lots of regular transistors
>>53791170
i meant max speed for it to be stable at processing anything
60Hz hurts my eyes though, i would prefer and strobe to be 20Hz
A Brainfuck CPU would probably be simple enough.
>>53791193
>60Hz hurts my eyes
Then stop using CRTs.
>>53790605
You've got diodes pointing in opposite directions there friendo
>>53789394
You aren't going to be doing much with an Intel 4004 anyways (they were only used in a few calculators if I remember correctly) so it wouldn't really hurt to design your own extremely basic processor instead. You could even make a device that would just multiply two values together if you wanted something really simple that would still have a clock.
>>53789394
Id do it with relays desu, sounds cool as fuck and shouldnt be hard to wire a led next to each one whenever it opens or closes.
>>53791287
CLACLACKLACKCLACKCLACKCLACK CLOCK CLOCK CLOCK CLACK CLACK CLACK CLOCK
try building something using 7400 series chips
>>53790605
>>53790633
Beside the wrong led orientation, what this circuit did is bypass led when switch is pressed.
The led will turn on because forward voltage now enough to turn the LED.
This is not how transistor works.
>>53791154
>As an EE it boggles my mind how far programmers seem to get away from hardware.
What...you mean an interpreted language on a virtual machine on a hypervisor on top of the OS isn't close to the bare metal?
>add two integers
>assembler: one machine instruction
>python: 9 billion machine instructions
For cool factor: just make an LED board with one light per register and copy a single core's register set out at a frequency that humans can observe, maybe even as slow as once per second.
>>53790605
>a transistor can be constructed with two LED's with their polarity's facing in opposite directions.
That's not how a real transistor works. It will not work if the N and P materials are not one beside the other.
The 4004 is 4-bit you retards.
>>53790940
Im talking about proving that you CAN make a transistor out of two LED's. If you actually wanted to use it for something of course you wouldnt use a physical switch.
>>53791095
That seems like a better idea. Would want it to be a true CPU, not just an asic chip designed to only add and subtract.
>>53791244
Thats the point. That's all a transistor is, two diodes pointing in the opposite direction. Applying current to the junction where they meet will allow current to flow from past it. Dont ask me why, that gets too far into quantum mechanics for me at this point..
>>53791327
>> CLACKCLACKCLACKCLACKCLACK CLOCK CLOCK CLOCK CLACKCLACKCLACK
lol'd hard
>>53791409
No, 5V is not enough to push current past a diode in the wrong direction, and opening and closing the switch will not change that.
>>53791666
yeah, you changed the diagram. the third LED goes AFTER the two pointing against each other. you put it in the wrong side.
>>53792011
then why did it seem to work when I tried it?
Nice try OP
https://www.quora.com/Why-cant-we-make-a-transistor-by-using-two-diodes-back-to-back
>>53789989
>gayming PSU
Stop STOP, it hurts!!
there is no fucking way you can make a BJT using two regular diodes.
>>53793715
>Im talking about proving that you CAN make a transistor out of two LED'
You haven't proved it has the I-V characteristic of an transistor.
>>53793715
>Thats the point. That's all a transistor is, two diodes pointing in the opposite direction.
No. It has been pointed out several times already that you are mistaken.
>>53789394
there's a guy who's made a web server out of logic ICs that I heard about years ago, dunno if his site is still up
>>53789394
Just build your own 6502 with TTLs
http://baltissen.org/newhtm/ttl6502.htm
>>53789394
You couldn't use LEDs because of the power consumption. You would need some fairly efficient transistors I think that would be the main issue. Also if you're using random transistors or LEDs you would need some resistors to not get awful power consumption and burn shit out. I really don't know how a IC transistor differs from a typical off the shelf one, but there are probably ways they get away with not caring about sticking resistors infront of everything (high input impedance?). There are likely other differences too, I would go into further reading.
>a transistor can be constructed with two LED's with their polarity's facing in opposite directions.
dear god what the fuck
>>53793715
>that's the point, that's all a transistor is
No, Jesus, no a transistor is a logic gate that allows current to flow through it once current is applied at its base
good luck. enjoy your lead solder poisoning.
>>53795598
I think I could use more clarification, because a copper wire lets current flow once applied to the base, yet I know a wire is not a transistor.
been told two wires of different materials could make one, but am suspicious of claim.
>>53789394
>a transistor can be constructed with two LED's with their polarity's facing in opposite directions.
No.
The border between the three layers is the main part of the transistor which makes a transistor a transistor.
Just by connecting two diodes together, you cannot make a transistor. It seems to be the same thing--on paper, but in reality it doesn't re-create the exact situation which is inside the transistor.
>>53793715
so from that I can assume this is some old ram chip? been wondering since I saw it
>>53791095
>>53795848
wrong post links sorry
>>53789394
>>> a transistor can be constructed with two LED's with their polarity's facing in opposite directions.
<giggle>
What else do you imagine?
>>53790437
>Yes, you can, Iv done it.
No, you can't. You haven't.
>>53795848
It's magnetic core memory. It was used as RAM, CPU registers, and every other piece of volatile memory. Computers hadn't reached the point of different types of memory for different tasks.
>>53789394
>>> a transistor can be constructed with two LED's with their polarity's facing in opposite directions.
>they really believe this
L O L
>>53795765
exactly
>>53795848
Dumbass
>>53795848
It looks like a magnetic memory array.
That's badass.
>>53795598
a transistor is used to MAKE logic gates, it is not one in and of itself...
>>53795957
>https://www.quora.com/Why-cant-we-make-a-transistor-by-using-two-diodes-back-to-back
>>53795960
>>53795992
>>53795765
>>53795598
>>53795535
>>53795251
>>53795152
>>53794630
Ok, I wont deny logic and say that the rest of the world is wrong and Im right, but explain to me what happened that made it look like I made a transistor? I honestly cant figure out what I was observing...
>>53789394
Do it with transistors, anon. LED idea is naive, bipolar transistor relies on more complex physical effect that is possible only when p-n junctions are on the same wafer.
https://en.wikipedia.org/wiki/Bipolar_junction_transistor
To minimize the percentage of carriers that recombine before reaching the collector–base junction, the transistor's base region must be thin enough that carriers can diffuse across it in much less time than the semiconductor's minority carrier lifetime. In particular, the thickness of the base must be much less than the diffusion length of the electrons. The collector–base junction is reverse-biased, and so little electron injection occurs from the collector to the base, but electrons that diffuse through the base towards the collector are swept into the collector by the electric field in the depletion region of the collector–base junction. The thin shared base and asymmetric collector–emitter doping are what differentiates a bipolar transistor from two separate and oppositely biased diodes connected in series.
Also read http://www.homebrewcpu.com/
I have designed and compiled my own simple CPU, it ran on FPGA.
>>53796913
>but explain to me what happened that made it look like I made a transistor?
Transistor should have gain.
Two diodes won't have gain because the physical effect that makes gain possible isn't there. They are like a transistor with gain < 1. To build logic circuits you need a switch with gate much bigger than 1.
>>53789996
>>53790057
Never mind the fact that if you make it too fast, you will no longer be able to see the LEDs blink.
>>53789394
Are you the fucking son of a cunt who outbidded me for the 4004 on ebay? I was going to make a fucking pseudo ibm-5100 with that.
>>53795449
Neat, probably a more viable project than trying to build an Intel 8008 from the Datapoint 2200 schematics I have at home (which used a complete TTL implementation of the Intel 8008).
>>53798236
>I was going to make a fucking pseudo ibm-5100 with that.
The fuck do you plan on doing with that?
>>53798892
Use it obviously. I was thinking of changing the system to allow a file manager or text based browser. If that didn't work, I'd sell it.
>>53799018
>text based browser
The Intel 4004 can only address 640 bytes of RAM you dunce. Just get a cheap microcontroller, you'd be able to do more.
>>53799260
That's true. Forgot the address rate. Still, those ones go for like 10,000 so when I make it with parts hell it'd bring in money.
>cheap mirocontroller
Better idea. If only I had a 3d printer to print out the chassis for the actual thing.
>>53798236
nope. But I am about to eat a microwave potato. And its gonna be delicious.
Uneducated anon here
Have you considered changing the scale to be more practical first?
I get you want to make a close to 1:1 led based CPU (I have no idea if it's possible but I'm not qualified to say it is or isn't) but could it be much more practical or even functionally better to make a much smaller or weaker version?
Why not start with an array of 4-bit cpus and see where that takes you? You could build a lot and make a controller of sorts that makes them functional a level of an 8-bit cpu
I have no idea whether this will work but it makes sense as I think about it, but probably not over text.
Or just make a CPU but make it 3D (like a lattice? Maybe a tesseract?) somehow instead of a 2D grid but also out of LEDs?
I do t understand electronic engineering, only mechanical engineering. And honestly if it were more of a 3D thing I stead of a bigass array you'd have far more people looking and intrigued than a 2D array
While I'm at it, if I'm wrong please do tell me.
>>53789959
You're still not going to accomplish anything because of the huge voltage drop compared to transistors.
If pairing diodes or leds would work as a xsistor Why not use photo-voltaic/LED pairs and have it be a self-powered perpetual motion cpu?
The old solar powered flashlight, then you could put it on a boat with a screen door in the hull
>>53798191
You can build AND or OR gates with gain less than 1. You've got to keep signal chains short because you lose 0.7v with each gate and it's impossible to do a NOT operation.
>>53789394
This won't work. Like ever.
>>53789394
So how would you go about making a makeshift simple processor then? If this isn't how. I'm genuinely curious and someone knows how here I know. They used to be made with vacuum tubes and other things.
>>53803196
Just use transistors, that's what processors are made of
>>53804007
Thats too simple though! What are old school alternatives?
