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MyNOR: Single board computer that uses a single NOR gate as its ALU

mynor.org

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Re: MyNOR: Single board computer that uses a single NOR gate as its ALU

#21

Post by pjc50 »

WalterGR wrote: post #19

What sort of simulator is required to go from “running” to ordering a prototype board 26 days later? I had assumed physical breadboards and wires and chips were always necessary to prototype... 2019-11-02 The first version of the MyNOR simulator is running. The circuit works! 2019-11-17 I have finished the work on the microcode. I added support for MyNOR to my cross-assembler myca. 2019-11-28 PCB layout completed. A…

Professionals generally have enough confidence to go straight to PCB. Solderless breadboards have enough capacitance that they aren't suitable for high-speed digital logic anyway.

Re: MyNOR: Single board computer that uses a single NOR gate as its ALU

#22

Post by progre »

WalterGR wrote: post #19

What sort of simulator is required to go from “running” to ordering a prototype board 26 days later? I had assumed physical breadboards and wires and chips were always necessary to prototype... 2019-11-02 The first version of the MyNOR simulator is running. The circuit works! 2019-11-17 I have finished the work on the microcode. I added support for MyNOR to my cross-assembler myca. 2019-11-28 PCB layout completed. A…

The simulation tool for Altera FPGA:s was pretty powerful when I used it a few years back. You'd basically drag and drop "packages" like the 74xx components, connect them and you could run the circuit with timing profiles and all. The purpose is of course not to actually then build it out of discrete logic but to synthesize it to a FPGA bit stream, but once you have the tool setup (it required something like 200 gigs if disc space and was extremely picky about drivers) I can see it being an option for this sort of thing.

Re: MyNOR: Single board computer that uses a single NOR gate as its ALU

#23

Post by garmaine »

pmiller2 wrote: post #14
theresistor wrote: post #9

Earlier quoted context omitted.

That’s just moving the composition between hardware and software - the equivalence still applies. I can build any logic (software) function out of a function that evaluates NOR.

False advertising, then, IMO.

...but that's exactly the claim, restated.

Re: MyNOR: Single board computer that uses a single NOR gate as its ALU

#24

Post by JPLeRouzic »

captn3m0 wrote: post #5
JPLeRouzic wrote: post #2

I wonder how this ALU works. From what I remember ALUs use lot of XOR gates because an adder is simply a network of XOR gates with carry propagation. How could a NOR gate do one bit addition? Add two bits ... XOR ... NOR 0 + 0 = 0...........0...........1 0 + 1 = 1...........1...........0 1 + 0 = 1...........1...........0 1 + 1 = 0...........0...........0

From the website: http://www.mynor.org/downloads/NOR-Logic.pdf

Thanks but in the linked PDF they use 12 NOR gates for a ONE bit adder.

Re: MyNOR: Single board computer that uses a single NOR gate as its ALU

#26

Post by avian »

I've met Dennis years ago at a vintage computer festival. He later visited our hackerspace to present his MyCPU project - a computer he built from ground up, including the CPU, graphics card, operating system and everything else. He's an amazing guy and his visit is one of the best memories I have of that place. Our hackerspace is gone now and I'm so happy he's still doing projects like this.

Re: MyNOR: Single board computer that uses a single NOR gate as its ALU

#27

Post by rcxdude »

WalterGR wrote: post #19

What sort of simulator is required to go from “running” to ordering a prototype board 26 days later? I had assumed physical breadboards and wires and chips were always necessary to prototype... 2019-11-02 The first version of the MyNOR simulator is running. The circuit works! 2019-11-17 I have finished the work on the microcode. I added support for MyNOR to my cross-assembler myca. 2019-11-28 PCB layout completed. A…

Nope. I design electronics professionally and I rarely do breadboard prototypes (and almost never using a solderless breadboard). This is because I can be reasonably confident about the behaviour of most circuits with perhaps a little bit of simulation using a SPICE model for some analogue parts. For complex digital logic (which is very rare to design using seperate ICs these days, you would use an FPGA) there is a multitude of simulation systems you can use as well to test your design (including some of the design tools for FPGAs).

PCBs can be made cheaply and on short notices these days (I can get 5-off a 4-layer PCB for $200 in 4 days, and that extends both cheaper if I can wait longer and shorter if I want to pay more), and solderless breadboards are atrocious for almost anything I'd want to prototype (the parasitic capacitances, inductances, and resistances are all really bad. sensitive analog circuits, high-speed digital, and power electronics all suffer badly from those).

Re: MyNOR: Single board computer that uses a single NOR gate as its ALU

#29

Post by JPLeRouzic »

pjc50 wrote: post #20
OJFord wrote: post #15

Earlier quoted context omitted.

Not with a ' single NOR gate'.

Yes .. if you feed its output to its input on the next cycle.

Then the ALU includes the sequencer and the microprogram.

Shifts are implemented with look-up tables.

Anyway it's a beautiful work.

Re: MyNOR: Single board computer that uses a single NOR gate as its ALU

#30

Post by srott »

pmiller2 wrote: post #14
theresistor wrote: post #9

Earlier quoted context omitted.

That’s just moving the composition between hardware and software - the equivalence still applies. I can build any logic (software) function out of a function that evaluates NOR.

False advertising, then, IMO.

No, AFAIU the computation is serialized, driven by the microcode and this gate is reused for every step
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