2.1.4 explain the machine instruction cycle

when software s installed onto a computer where are the program and any associated files stored?

secondary memory

when progams are installed how is the code stored?

as a series of bits that represent machine instructions

What happens when the user chooses to execute a program?

Sections of the code are loaded into the computer’s memory.

what are the 4 steps of program execution?

1. installation from source media

2. program installed onto hard drive

3. program loaded into memory

4. program executed by CPU

what is a hard drive?

a piece of hardware used to store digital content and data on computers

what are the 4 steps of saving data?

1. results obtained from CPU

2. data stored in memory

3. data saved to hard drive

   1. data possibly archived on external media

what is the machine cycle?

how the processor retrieves instructions one by one from memory in order to run code

what is the first step of the machine cycle?

fetch

CU looks at the program counter register for the memory address of the next instruction

this instruction is requested from main memory and placed in the instruction register

what is the second step of the machine cycle?

decode

the CU checks the instruction in the instruction register and decides what needs to be done.

Binary instruction is interpreted to figure out task

what is the third step of the machine cycle?

execute

the CU sends signals telling the required components to perform the correct work

what is the fourth step of the machine cycle?

The CPU may be required to store the result of an instruction in memory or it may be sent to an output device

where does the fetch portion occur?

PC > MAR > RAM > MDR > CIR

where does the decode portion occur?

CU

where does the execute portion occur?

ALU

where does the store portion occur?

accumulator