Computers: Hardware Terms Flashcards
What is the Central Processing Unit (CPU)?
- Processes data and instructions.
- Fetches, Decodes, Executes instructions from the memory
- Contains CU, ALU, and Accumulator
What is the Control Unit (CU)?
- Sends control signals that control hardware in all stages of the FDE cycle.
- Decodes instructions during the decode stage
- Contains the Instruction register and the PCR
What is the ALU?
- Performs mathematical and logical operations
What is a register?
- A small amount of high speed memory contained on the CPU
- Stores a small amount of data such as an instruction or a memory address
What are the 4 registers?
- Program Counter (PC)
- Memory Address Register
- Memory Data Register
- General Registers
What does the Program Counter do (PC)?
- Holds the memory address of the next instruction to be fetched
What does the Memory Address Register (MAR) do
- Holds the address of the current instruction/data that is to be fetched from memory
What does the Memory Data Register (MDR) do?
- Holds the contents of the memory address that has been fetched. E.G. an instruction or data.
What do the General Registers do?
- Holds the results of any calculations/logic operations
What is a Bus?
A high speed internal connection between components.
What is the Address Bus?
A unidirectional bus that carries memory addresses from the CPU to the RAM
What is the Control Bus?
A bus in which the CU sends control signals to other hardware
What is the Data Bus?
A bidirectional bus that carries data and instructions from RAM to the CPU and vice versa
What is Cache?
- A small amount of memory built directly onto the processor
- Holds instructions the processor is likely to reuse
What is Clock Speed?
- How many times FDE cycles can be completed per second. Measured in Hertz
- A component called a clock synchronises how many cycles per second the CPU will operate
What is Random Access Memory (RAM)?
- Often referred to as just memory
- Holds the instructions and data currently in use
- It is volatile (loses data when power is lost
What is Secondary Storage?
- Permanent storage
- AKA non volatile
How does a Magnetic drive work?
Uses magnetic polarity to represent 1s and 0s
How does a Solid State drive work?
Uses stored electric charges to represent 1s and 0s (held in NAND transistors)
How does an Optical drive work?
Uses a laser to burn pits and lands onto a disc to represent 1s and 0s
What is an Embedded System?
- A computer system with a single role.
- Usually smaller, less powerful devices. E.G. Washing machine controls
- Usually work in real time and often have sensors
What is a General Purpose System?
A device designed to perform a wide range of tasks and applications, rather than being limited to specific functions
