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1-bit computing
Computer architecture bit width / From Wikipedia, the free encyclopedia
In computer architecture, 1-bit integers or other data units are those that are 1 bit (1/8 octet) wide. Also, 1-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers of that size.
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There are no computers or microcontrollers of any kind that are exclusively 1-bit for all registers and address buses. A 1-bit register can only store two different values. This is very restrictive and therefore not enough for a program counter which, on modern systems, is implemented in an on-chip register, but is not implemented on-chip in some 1-bit systems. Opcodes for at least one 1-bit processor architecture were 4-bit and the address bus was 8-bit.
While 1-bit computing is mostly obsolete, 1-bit serial communication is still used in modern computers, that are otherwise e.g. 64-bit, and thus also have much larger buses.
While 1-bit CPUs are obsolete, the first carbon nanotube computer from 2013 is a 1-bit one-instruction set computer (and has only 178 transistors; since it has only one instruction though it can emulate 20 MIPS instructions).[1]