Generates signals within uP to carry out the instruction, which
has been decoded. In reality causes certain connections between
blocks of the uP to be opened or closed, so that data goes where
it is required, and so that ALU operations occur. Arithmetic
Logic Unit The ALU performs the actual numerical and logic
operation such as ‘add’, ‘subtract’, ‘AND’, ‘OR’, etc. Uses data
from memory and from Accumulator to perform arithmetic. Always
stores result of operation in Accumulator. The
8085/8080A-programming model includes six registers, one
accumulator, and one flag register, as shown in Figure. In
addition, it has two 16-bit registers: the stack pointer and the
program counter. They are described briefly as follows. The
8085/8080A has six general-purpose registers to store 8-bit
data; these are identified as B,C,D,E,H, and L as shown in the
figure. They can be combined as register pairs - BC, DE, and HL
- to perform some 16-bit operations. The programmer can use
these registers to store or copy data into the r