Computer Science & Electrical Engineering: The ALU & The Registers

The ALU & The Registers

The ALU:

• In addition to the arithmetic & logic circuits, the ALU includes the accumulator, which is part of every arithmetic & logic operation.

• Also, the ALU includes a temporary register used for holding data temporarily during the execution of the operation. This temporary register is not accessible by the programmer.

The Registers:

– General Purpose Registers
• B, C, D, E, H & L (8 bit registers)
• Can be used singly
• Or can be used as 16 bit register pairs

– BC, DE, HL
• H & L can be used as a data pointer (holds memory address)
– Special Purpose Registers

• Accumulator (8 bit register)
– Store 8 bit data
– Store the result of an operation
– Store 8 bit data during I/O transfer