REGISTERS
The 8085 has six general purpose registers to store 8 bit data. These are identified as B, C, D, E, H, L. they can be combined as register pairs BC, DE, and HL, to perform 16 bit operations.

ACCUMULATOR
The acc is an 8 bit register that is part of the arithmetic logic unit [ALU]. This register is used to store 8 bit data and to perform arithmetic and logical operations. The result of the operation is stored in the accumulator and identified as A.

FLAGS
The arithmetic logic unit [ALU] includes 5 flip flops which are set or reset after an operation according to data conditions of the result in the accumulator and other registers. They are called zero (Z), carry (CY), sign(S), parity (P), and auxiliary carry (AC). The microprocessor used these flags to test data conditions.

PROGRAM COUNTER
The microprocessor uses the PC register to sequence the execution of the instructions. The function of the pc is to point to the memory address from which the next byte is to be fetched. When a byte is being fetched, the pc is increased by one to point to the next memory location.

STACK POINTER
The sp is also a 16 bit register used as a memory pointer. It points to a memory location in R/W memory, called the stack.