System Architecture
1.1.1 Architecture of the CPU
The CPU:
The purpose of the CPU is to process data. It does this by coordinating and
carrying out the fetching, decoding and execution of (carrying out)
instructions. The instructions are used to process the data.
Data: computer instructions can be considered as data.
Values: used to refer to the clear distinction between data that is executable
(instructions) and non-executable data (values such as the current score you
have in a video game.)
The main sections of a CPU:
➔ Registers (areas of memory that help a processor to carry out an
instruction)
➔ Units (Control unit, Arithmetic logic unit)
➔ Cache memory (in modern CPUs, the cache memory can temporarily
store some instructions to save the computer getting them from its
memory which takes longer)
A computer system: a set of digital inputs, processes them and creates a set
of outputs. This is done by a combination of hardware and software.
In order to do this, the computer needs instructions to tell it what to do. The
instructions are provided by a program
E.g. a laptop or desktop computer, smart phones
, An instruction may:
➔ Perform arithmetic or logic* operations on data
➔ Perform input/output of data
➔ Control program flow**
Sequence: One instruction gets executed after another.
Selection: Different code gets executed depending on the answer to a
question. e.g. different code will run in a video game depending on the
difficulty level selected.
Iteration: The same code will continue to run a number of times, or either until
or while a condition is true. e.g. the code for running a video game will run
until you have no lives left.
System Inputs from input devices Processes Outputs from output
devices
Cash
machine ● PIN (Personal ● Check ● Cash
identification number) PIN dispensation
● Card data read from ● Check ● Beeps
chip account ● Printed receipt
● Service selection (e.g. balance
withdraw cash, check
balance etc)
● Amount to withdraw
Digital
camera ● Button presses ● Process ● Beeps
● Light button ● Display
presses preview/review of
● Process image
light
signal
1.1.1 Architecture of the CPU
The CPU:
The purpose of the CPU is to process data. It does this by coordinating and
carrying out the fetching, decoding and execution of (carrying out)
instructions. The instructions are used to process the data.
Data: computer instructions can be considered as data.
Values: used to refer to the clear distinction between data that is executable
(instructions) and non-executable data (values such as the current score you
have in a video game.)
The main sections of a CPU:
➔ Registers (areas of memory that help a processor to carry out an
instruction)
➔ Units (Control unit, Arithmetic logic unit)
➔ Cache memory (in modern CPUs, the cache memory can temporarily
store some instructions to save the computer getting them from its
memory which takes longer)
A computer system: a set of digital inputs, processes them and creates a set
of outputs. This is done by a combination of hardware and software.
In order to do this, the computer needs instructions to tell it what to do. The
instructions are provided by a program
E.g. a laptop or desktop computer, smart phones
, An instruction may:
➔ Perform arithmetic or logic* operations on data
➔ Perform input/output of data
➔ Control program flow**
Sequence: One instruction gets executed after another.
Selection: Different code gets executed depending on the answer to a
question. e.g. different code will run in a video game depending on the
difficulty level selected.
Iteration: The same code will continue to run a number of times, or either until
or while a condition is true. e.g. the code for running a video game will run
until you have no lives left.
System Inputs from input devices Processes Outputs from output
devices
Cash
machine ● PIN (Personal ● Check ● Cash
identification number) PIN dispensation
● Card data read from ● Check ● Beeps
chip account ● Printed receipt
● Service selection (e.g. balance
withdraw cash, check
balance etc)
● Amount to withdraw
Digital
camera ● Button presses ● Process ● Beeps
● Light button ● Display
presses preview/review of
● Process image
light
signal
