8 Bit Processing

Building an 8 bit computer with logic gates (integrated circuits) and discrete components

Simple-As-Possible

The structure of this computer centers around a single 8 bit bus. Several modules are attached to the bus and process the bits of data (address bits and data bits). These modules include a program counter, a memory address register, random access memory, an instruction register, an accumulator, a B register, an arithmetic logic unit (ALU), an output register, a set of 7-segment displays to display the contents of the output register, and control logic to coordinate the processing of the bits. The computer timing is controlled by a system clock that interacts with the modules to process bits and move the flow of bits logically.

Each of the modules is created separately and interact with the other modules via the bus or through a direct connection to another module. The modules are created using logic gates, such as 74LS173 to store data (D flip-flops), and 74LS245 (tri-state octal bus transceivers) that allows the orderly transfer of data to the bus.

System Clock

The system clock centers around the 3 operating modes of the 555 timer.