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Youtuber Ben Eater is uploading a series of instructional videos on building a programmable 8-bit computer from digital logic circuits on breadboards. No soldering required. The series is ongoing, updated weekly.
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Building an 8-Bit Breadboard Computer
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Cum tacent, clamant. When they are silent, they shout. -Cicero
(Score: 1) by a-zA-Z0-9$_.+!*'(),- on Monday May 08 2017, @01:59PM
I watched some of these yesterday.
https://newrepublic.com/article/114112/anonymouth-linguistic-tool-might-have-helped-jk-rowling
(Score: 4, Insightful) by Arik on Monday May 08 2017, @02:07PM (2 children)
If laughter is the best medicine, who are the best doctors?
(Score: 2) by c0lo on Monday May 08 2017, @05:28PM
I don't question the security, but correctness... really...? On breadboards? With so much stray capacitance and inductance and lousy connections?
Perhaps it will be correct if you run it on hundred kilohertz clock frequency but I wouldn't bet for more.
https://www.youtube.com/watch?v=aoFiw2jMy-0
(Score: 3, Interesting) by kaszz on Monday May 08 2017, @06:43PM
Have a look at the Intel 4004 replica project [4004.com]. It's a 41 x 58 cm (1.3 x 1.9 ft) 130x scale replica of the 4-bit and 2300 transistor CPU.
The Motorola 68020 which is MMU and FPU expandable uses 190 000 transistors and would using the same method require 20 m² (215 ft²). The Intel 80386 requires 28 m² (306 ft²).
But one could target the MOS 6502 with 3510 transistors which would require 0.36 m² (3.9 ft²) ie something like 60 x 60 cm. And compensate for the 8-bits by increasing the clock frequency. Assembly done by a pick & place robot will make this task efficient and the different types of components will be limited so a big spool of transistors will push the price down.
There are of course even easier methods for a secure computer depending on the amount of trust you have. Or skills to thwart any would be spies.
(Score: 0) by Anonymous Coward on Monday May 08 2017, @02:16PM (1 child)
A computer capable of running Windows 10, using vacuum tubes as transistors. It would probably require a nuclear power plant to power it up though.
(Score: 2) by LoRdTAW on Monday May 08 2017, @04:13PM
The sun if it's running Crysis. (ducks)
(Score: 5, Interesting) by VLM on Monday May 08 2017, @02:33PM (1 child)
Microscopically better link here:
https://eater.net/8bit/ [eater.net]
Videos are too expensive. I'm not gonna burn 8 hours to find out he's using cascaded '283 as binary adders, I'll just check out the dudes website. Not a bad chip, does fast carry on die and cascading isn't the worst idea ever if you're only cascading two (no look ahead carry gen). I can't remember the difference between a 74ls83 and a 74ls283, I'm sure the '283 is faster. I'm pretty sure the '83 had on chip fast carry generation just like the '283...
He had to go to ebay to get pulled 28C16 eeproms because 2 kilobyte eeproms are kinda obsolete. Personally I would have bought something like a AT28C256 which is a 32 kilobyte eeprom, which is currently being manufactured new in DIP packages, then forced the MSB to all zero, or had some fun with bank switching in sixteen different 2K roms. Its not a cost problem those are like $5 new from atmel and he probably paid more than $5 shipping for the pulled used 28C16 from ebay. At least his ebay chip worked and wasn't fake. Lots of fakes or dead chips on ebay. And of course eeprom's don't last forever and I wonder how used up his used 28c16 is...
Just to be a jerk, rather than hand wiring 100 or so T-1 3/4 discrete LEDs he could have got some legacy TIL311 from ebay or those little bargraph array things, looks a little neater, easier to wire. TIL311 give little hex digit display which is cool, although they're very power hungry, and unfortunately collectible (aka expensive, like $10 each hex digit, but they look sooo cooool)
His wiring is ridiculously clean. I suppose if I knew my wiring was going to be a video series I would make it look good. Just saying real world breadboards usually don't look that nice, LOL.
His ALU doesn't actually do any L as in logic, just add registers with inverted (subtract) output. A simple extension would be installing a couple more 74LS245, and then doing the barrel roller so at least he could do rolls and shifts, or wire up about two 7400 and a '245 so he could have NAND logic output. Its a pity 74181 are obsolete. Now you think about it, a 74181 is like a memory that has 4+4+4+1+1 = 14 address lines and 5 data lines. Two four bit inputs and an fuor bit operation code and a mode bit and a carry bit is 14 bits of input and one four bit output plus a carry bit is 5 bits. Now 74181 ran in like "double nanoseconds" and a 28C256 runs in like 150 nanosecond but speed is probably not an issue and a 28C256 eeprom has 15 bits of input "address" resulting in 8 bits of output "data" so an emulated 74181 will easily fit in a modern 32Kilobyte eeprom that is new and costs $5. I'm just saying he could have had a 74181 equivalent hell of an ALU by using two eeproms programmed to act like 74181 chips. Thats how I wouldda dunnit anyway.
his program counter register parts list implies he only has 4 bits of PC whaa? I assume he meant two '245 and four '161... probably.... There was an elegant DEC design in the 60s that used some microcoding hardware to abuse memory location 0 to hold the PC and writes to 0 are unconditional jumps and self modifying code is conditional jumps and you can use the ALU adder to increment PC ... it takes a lot of hardware to implement but then you don't need a separate PC. It also makes it slow, but usually speed isn't an issue.
Its an interesting believable design. Engineering is very creative occupation as much as liberal arts types think otherwise, which leads to lots of commentary about big designs, like this.
Its cool.
(Score: 2) by art guerrilla on Monday May 08 2017, @02:42PM
unfortunately, no mod for 'most excellent nerding', had to go 'interesting'...
(Score: 2) by dbe on Monday May 08 2017, @05:42PM
Just saw that one recently, while it's not on a breadboard, it was modeled at gate level:
https://www.youtube.com/watch?v=lNa9bQRPMB8 [youtube.com]
I do like the speedometer functionality to change the overall clock at will, also bonus points for the led displays of all the gates & memory locations.
Cheers
-dbe
(Score: 1) by HighOrbit on Monday May 08 2017, @08:05PM
On a similar note, I am running through the Nand2Tetris book and courses aka "Building a Modern Computer from First Principles".
http://www.nand2tetris.org/ [nand2tetris.org]
The Nand2Tetris course is not a physical build (everything is done on a hardware simulator), but it shows how to bootstrap from boolean logic to NAND gates to a working (but simple) ALU to finally a working general purpose computer.