The CPU processes instructions and data that are input into the computer
so that the result can be output
A microprocessor is a type of integrated circuit on a single chip
Von newman obeys the stored program concept:
● Programs and instructions are stored in memory
● Instructions are fetched one after another
● Data is stored in memory
The purpose of the components in a CPU:
- ALU
- CU
- Registers
- Busses
Role ALU:
The arithmetic logic unit carries out calculations and logical operations, it
also holds temporary values during calculations in a register called the
accumulator
Role of CU:
It sends control signals that manage the transfer of data and instructions
within the CPU It also decodes an instruction using an instruction set and
controls the flow of data through the CPU
,5 types of registers:
- PC (program counter)
- MAR (memory address register)
- MDR (memory data register)
- CIR (current instruction register)
- ACC (Accumulator)
The role of registers is to store and hold data temporarily
PC: A register that holds the address of the next or current instruction to be
processed.
MAR: A register that holds the address of the data or instruction that needs
to be fetched or processed IT ALSO holds the address of where the
data needs to be stored.
MDR: This is a register that store data or an instruction that has been
fetched from memory
CIR: Contains the instruction / data to be decoded
ACC: This is a register that is built into the arithmetic logic unit. It temporary
holds the result of a calculation
,Buses:
Address bus
Data bus
Control bus
primary function of the bus is to transmit data and signals between
the various components within a computer system
Data bus responsible for transmitting data/instructions between
components in CPU BIDIRECTIONAL
Control bus responsible for transmitting control signals FROM control unit
to all other computer components BIDIRECTIONAL (data can travel both
directions)
Address bus responsible for transmitting addresses between components
in the CPU and memory UNIDIRECTIONAL
, FETCH-DECODE-CYCLE
1. The program counter (PC) stores the address of the memory location
of the next instruction which has to be fetched
2. This location is copied into memory data register (MDR) using
address bus
3. The memory address is sent using address bus
4. The Program Counter is incremented by 1 so now it points new
instruction to be fetched
5. The instruction is sent from the address in memory to the Memory
Data Register (MDR)
6. The instruction is transferred using the data bus
7. The instruction is sent to Current Instruction register (CIR)
Factors that determine performance of a CPU:
- System clock (clock cycle) (clock speed)
- Bus width
- Cache size
- Number of cores
so that the result can be output
A microprocessor is a type of integrated circuit on a single chip
Von newman obeys the stored program concept:
● Programs and instructions are stored in memory
● Instructions are fetched one after another
● Data is stored in memory
The purpose of the components in a CPU:
- ALU
- CU
- Registers
- Busses
Role ALU:
The arithmetic logic unit carries out calculations and logical operations, it
also holds temporary values during calculations in a register called the
accumulator
Role of CU:
It sends control signals that manage the transfer of data and instructions
within the CPU It also decodes an instruction using an instruction set and
controls the flow of data through the CPU
,5 types of registers:
- PC (program counter)
- MAR (memory address register)
- MDR (memory data register)
- CIR (current instruction register)
- ACC (Accumulator)
The role of registers is to store and hold data temporarily
PC: A register that holds the address of the next or current instruction to be
processed.
MAR: A register that holds the address of the data or instruction that needs
to be fetched or processed IT ALSO holds the address of where the
data needs to be stored.
MDR: This is a register that store data or an instruction that has been
fetched from memory
CIR: Contains the instruction / data to be decoded
ACC: This is a register that is built into the arithmetic logic unit. It temporary
holds the result of a calculation
,Buses:
Address bus
Data bus
Control bus
primary function of the bus is to transmit data and signals between
the various components within a computer system
Data bus responsible for transmitting data/instructions between
components in CPU BIDIRECTIONAL
Control bus responsible for transmitting control signals FROM control unit
to all other computer components BIDIRECTIONAL (data can travel both
directions)
Address bus responsible for transmitting addresses between components
in the CPU and memory UNIDIRECTIONAL
, FETCH-DECODE-CYCLE
1. The program counter (PC) stores the address of the memory location
of the next instruction which has to be fetched
2. This location is copied into memory data register (MDR) using
address bus
3. The memory address is sent using address bus
4. The Program Counter is incremented by 1 so now it points new
instruction to be fetched
5. The instruction is sent from the address in memory to the Memory
Data Register (MDR)
6. The instruction is transferred using the data bus
7. The instruction is sent to Current Instruction register (CIR)
Factors that determine performance of a CPU:
- System clock (clock cycle) (clock speed)
- Bus width
- Cache size
- Number of cores
