MyNOR: Single board computer that uses a single NOR gate as its ALU
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Re: MyNOR: Single board computer that uses a single NOR gate as its ALU
#2I 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
Re: MyNOR: Single board computer that uses a single NOR gate as its ALU
#3I used to work for a company that produced Flash Memory developed on NAND gates. Later, they attempted a product line of FPGAs... you keep calling this a CPU, but it seems similar to a FPGA. How is this different than a FPGA (if at all)?
Re: MyNOR: Single board computer that uses a single NOR gate as its ALU
#4I 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
NOR (like NAND) is a universal logic gate. You can build any other logic gate out of just NORs.
For this ALU, you’d presumably write a subroutine that computed XORs in terms of NORs, and then use that as a primitive for building an adder.
Re: MyNOR: Single board computer that uses a single NOR gate as its ALU
#5I 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
Re: MyNOR: Single board computer that uses a single NOR gate as its ALU
#6I 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
NOR (like NAND) is a universal logic gate. You can build any other logic gate out of just NORs. For this ALU, you’d presumably write a subroutine that computed XORs in terms of NORs, and then use that as a primitive for building an adder.
Yes, but this thing advertises that it uses a single NOR gate as an ALU.
Re: MyNOR: Single board computer that uses a single NOR gate as its ALU
#7I 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
http://www.mynor.org/downloads/MyNOR-HowItWorks.pdf has some more info.
Re: MyNOR: Single board computer that uses a single NOR gate as its ALU
#8I 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
The nor gate (like nand) is a universal gate. You can implement all the other gate with a combination of nor gate. See https://en.m.wikipedia.org/wiki/NOR_logic#XOR for example.
Re: MyNOR: Single board computer that uses a single NOR gate as its ALU
#9Earlier quoted context omitted.
NOR (like NAND) is a universal logic gate. You can build any other logic gate out of just NORs. For this ALU, you’d presumably write a subroutine that computed XORs in terms of NORs, and then use that as a primitive for building an adder.
Yes, but this thing advertises that it uses a single NOR gate as an ALU.
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.
Re: MyNOR: Single board computer that uses a single NOR gate as its ALU
#10I 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
I think the idea is that you use registers and apply the NOR gate multiple times. In this sense the NOR gate is universal, while an OR gate nor a XOR gate are neither universal.
I.e.
XOR(x,y) = NOR(0, NOR(NOR(x,y), NOR(NOR(x,0),NOR(y,0)))))