CS - 4) CPU ARCHITECTURE

What is General Purpose Register?

- Hold temporary data when performing operation
- Used for any purpose
- Can be used by most instructions

What is Special Purpose Register?

- Holds status of a program
- Specialised for specific use
- Can only by certain instruction

What is Program Counter?

- Holds the address of the next instruction to be loaded
- Is incremented once an instruction has been carried out

What is Memory Address Register?

Stores the address from memory location that is being read from or written to

What is Memory Data Register?

- holds data that is fetched from address in MAR
- Data is copied CIR

What is Current Instruction Register?

- holds the instruction that is currently being decoded and executed
- Holds data from MDR

What is Index Register?

Stores value that is added to an address to give to another address

What is Status Register?

- Stores flags from results of ALU
- Contains bits that can be set up individually depending on operation

What is CU?

- Synchronises actions of other components in CPU
- Sends/receives control signals along the control bus
- Manages the execution of instructions

What is system clock?

- synchronizes computer operations by creating time signals
- Allows operations to be processed in the correct order

What is Immediate Access Store?

- Holds data that is currently in use
- Volatile memory

What is address bus?

Carries address where data is going to be written to or read from

What is data bus?

Carries data between devices, buffer or components

How to increase bus performance?

- Higher clock speed means more FE cycles per second
- Increase the number of cores to allow more instruction to be carried out at the same time
- Higher Bus width will allow transfer of data each time and allows more memory location to be accessed directly.

What is the purpose of Ports?

To provide connection to peripherals and provide interface between computer and other device

Describe USB

- 1 bit transferred at a time
- Can be synchronous or asynchronous
- Faster data transfer speed

What is HDMI?

- Allows video and audio to be transferred to one cable

Explain the Fetch-Execute Cycle

- PC stores the address of the next instruction to be fetched and the contents will be incremented each cycle
- MAR holds the address where data is fetched from
- MDR holds the address in MAR
- Instruction from MDR is copied to CIR for execution and decoding

[PC] <-- [PC] + 1

Address in PC is being incremented

MAR <-- [PC]

Contents of PC is loaded into MAR

MDR <-- [[MAR]]

Data in address held in MAR is copied into MDR

CIR <-- [MDR]

Contents of MDR is copied into CIR

What is the purpose of an interrupt?

- to send signal from a device
- to seek the attention of a processor