4 Processor Fundamentals
4.1 Central Processing Unit (CPU) Architecture
Show understanding of the basic Von Neumann model for a computer
system and the stored program concept
In a classic Von Neumann computer, instructions and data are both
stored in the same shared memory space and have one system bus
connecting them. One address bus, one control bus and one data bus.
Stored program concept:
Show understanding of the purpose and roles of the Arithmetic and
Logic Unit (ALU), Control Unit (CU) and system clock, Immediate Access
Store (IAS)
The ARITHMETIC LOGIC UNIT (ALU) handles the data processing
inside the CPU.
It consists of two types of processing:
1. Arithmetic operation - it performs standard arithmetic operations
such as addition, subtraction, multiplication
2. Logic operation - it deals with logic and comparisons such as 'is this
value greater than that value' the answer is always either 'true' or
4 Processor Fundamentals 1
, 'false'.
The result can be stored anywhere in memory with the relevant
command. But for efficient programming, the result tends to be stored
in the accumulator register. Along with the answer, a flag is set by the
status register.
The CONTROL UNIT has three main jobs
1. It controls the way data moves around the CPU by controlling the
buses.
2. It controls and monitors the flow of data between the CPU and other
components such as input devices, memory, graphics card etc
3. It executes the instructions provided by the program.
The collection of instructions it can carry out is called the 'instruction
set' of the CPU. The instruction set is hard-wired into the CPU when it
was designed.
SYSTEM CLOCK:
A CPU is a sequential machine i.e. a processing core within it carries
out one instruction at a time. To coordinate this action, the CPU has an
internal quartz crystal clock that runs at a certain speed (the clock
frequency or more commonly referred to as 'clock speed’).The higher
the clock frequency, the faster the CPU can run and the more
instructions that can be processed every second.
IMMEDIATE ACCESS STORE:
4 Processor Fundamentals 2
4.1 Central Processing Unit (CPU) Architecture
Show understanding of the basic Von Neumann model for a computer
system and the stored program concept
In a classic Von Neumann computer, instructions and data are both
stored in the same shared memory space and have one system bus
connecting them. One address bus, one control bus and one data bus.
Stored program concept:
Show understanding of the purpose and roles of the Arithmetic and
Logic Unit (ALU), Control Unit (CU) and system clock, Immediate Access
Store (IAS)
The ARITHMETIC LOGIC UNIT (ALU) handles the data processing
inside the CPU.
It consists of two types of processing:
1. Arithmetic operation - it performs standard arithmetic operations
such as addition, subtraction, multiplication
2. Logic operation - it deals with logic and comparisons such as 'is this
value greater than that value' the answer is always either 'true' or
4 Processor Fundamentals 1
, 'false'.
The result can be stored anywhere in memory with the relevant
command. But for efficient programming, the result tends to be stored
in the accumulator register. Along with the answer, a flag is set by the
status register.
The CONTROL UNIT has three main jobs
1. It controls the way data moves around the CPU by controlling the
buses.
2. It controls and monitors the flow of data between the CPU and other
components such as input devices, memory, graphics card etc
3. It executes the instructions provided by the program.
The collection of instructions it can carry out is called the 'instruction
set' of the CPU. The instruction set is hard-wired into the CPU when it
was designed.
SYSTEM CLOCK:
A CPU is a sequential machine i.e. a processing core within it carries
out one instruction at a time. To coordinate this action, the CPU has an
internal quartz crystal clock that runs at a certain speed (the clock
frequency or more commonly referred to as 'clock speed’).The higher
the clock frequency, the faster the CPU can run and the more
instructions that can be processed every second.
IMMEDIATE ACCESS STORE:
4 Processor Fundamentals 2
