A 1-bit computer architecture is an instruction set architecture for a processor that has datapath widths and data register widths of 1 bit (1/8 octet) wide.
An example of a 1-bit architecture that was actually marketed as a CPU is the Motorola MC14500B Industrial Control Unit. There are also several design studies for 1-bit architectures in academia, and corresponding 1-bit logic can also be found in programming.
Other examples of 1-bit architectures are programmable logic controllers.
Several early Massively parallel computers used 1-bit architectures for the processors. Examples include the Goodyear MPP and the Connection Machine. By using a 1-bit architecture for the individual processors a very large array (e.g.: the Connection Machine had 65,536 processors) could be constructed with the chip technology available at the time. In this case the slow computation of a 1-bit processor was traded off against the large number of processors.
A typical sequence of instructions from a program for a 1-bit architecture might be:load digital input 1 into a 1-bit register;
OR the value in the 1-bit register with input 2, leaving the result in the register;
write the value in the 1-bit register to output 1.
This architecture was considered superior when the program makes the decisions rather than performing computations, ladder logic, also for serial data processing.
1-bit CPUs can be considered obsolete now, not many kinds have been produced (MC14500B and WDR-1 known) and none known to be available in the major computer component stores (as of 2016, a few on eBay). Finnish company Partco still sells MC14500B as spare part in 2017.