Unit 3 - Hardware Flashcards
What are some examples of input devices on a laptop and smartphone?
Laptop: keyboard, buttons, trackpad, microphone
Smartphone: microphone, buttons, GPS sensor, gyroscopic sensor, touch part of the touchscreen
What are some examples of output devices?
Laptop and smartphone: speakers, display
What component carries out the processing of the instructions?
CPU (Central Processing Unit)
What is the purpose of the CPU?
When you run a program, it is the CPU which processes the instructions and data that is input, the results are then output
What are the components of the CPU?
2 Major components - Control Unit and ALU (Arithmetic-Logic Unit)
There are also registers and cache
List the different registers in the CPU:
- Program counter (PC)
- Memory Address Register (MAR)
- Memory Data Register (MDR)
- Current Instruction register (CIR)
- Accumulator (ACC)
What is a PC?
A Program counter holds the address of the next instruction to be fetched from the primary memory.
What is a MAR?
It holds the memory address of the current instruction, and then the data that it uses, so that these can be fetched from memory.
What is the MDR?
It holds the contents found at the address held in the MAR, or data which is to be transferred to primary memory
What is the CIR?
The current instruction register holds the instruction currently being executed or decoded
What is the ACC?
The accumulator holds the result of an instruction before it is transferred to memory.
What is the control unit?
The control unit coordinates and controls all of the activities taking place within the CPU
- It decodes instructions and executes them
- It receives signals from the system clock
- It directs the timing and control of other parts of the - CPU, much like the conductor of an orchestra
What is the ALU?
The arithmetic logic unit is where the actual arithmetic operations are done. It also carries out logical operations such as those including AND, OR and NOT.
What is the fetch-decode-execute cycle?
FETCH – causes the next instruction and any data involved to be fetched from main memory
DECODE – decodes the instruction
EXECUTE – the instruction is executed
What is the PC?
The Program Counter holds the address of the next instruction to be executed
The Program Counter is incremented (increased by 1) as soon as that instruction has been fetched
What happens in the Fetch stage of the F-E-D cycle?
the address of the instruction to be executed is copied from the Program Counter (PC) to the Memory Address Register (MAR)
The instruction at that address is fetched from memory and copied to the Memory Data Register (MDR)
The Control Unit decodes the instruction and decides if data needs to be fetched
If so, the MAR is then used to hold the address of the data to be used in the instruction
The data is fetched and copied to the MDR
How does the MDR and MAR work together?
The MAR knows where to look for data in RAM, the MDR keeps hold of that data until it’s ready to be used by the CPU
What does the CIR do?
The current instruction register holds the instruction that is being executed or decoded at the moment
Name the three factors effect CPU performance and what they do:
- Clock speed (The number of duplicate processing units (cores) placed in one CPU)
- Processor cores (Cycles per second measured in hertz (Hz))
- Cache (Cache on the CPU is faster than RAM but slower than registers)
What is clock speed?
Everything in a computer happens on the pulse of the internal clock. Therefore, the faster the clock speed, the faster the instructions are processed
What is a processor core?
One cycle per second = 1 hertz (Hz) = 1 instruction carried out each second
What is a multi-core processor and what effect does it have on speed?
This allows twice as many instructions to be executed, however, it doesn’t always perform at this rate as software may not be able to take full advantage of both cores. A quad-core processor working on many different tasks simultaneously, under ideal conditions can be up to four times faster than a single-core processor
What is a disadvantage of a quad-core processor
If the computer is running a single program, it is not necessarily any faster, since the program may have been designed to only run on one core. The core can also heat up a lot.
What is Cache memory?
Cache is a small amount of very fast, expensive memory in the CPU. It can be accessed faster than regular main memory (RAM)