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input - data from the real world that’s stored and processed to outputs in a computer
Outputs
Memory(primary storage) - holds or stores data/ programs/ operating systems currently being executed or in use
Secondary storage
List and explain the basic models of a computer
He developed the concept of storage program computers, he used the idea data and programs can be stored in memory
Explain Von Neumann architecture
Is a hardware that executes programs and manages the rest of the hardware
What’s a CPU
A cache is a very fast memory that temporarily stores or holds data that will be needed by the processor during the course of running a program
What’s a cache
decides instructions
It’s controls and regulates processor timings using regular pulse from a system clock
It’s sends and receives control signals to and from other devices within a computer
It controls the execution of instructions in the correct sequence
Functions of the control unit
cache
ALU
Registers
list what the processor consists of
Fetching the
Explain the fetch decode execute cycle
Registers are very fast memory located in the CPU used in the execution of instructions
What are registers
MDR: they hold data or instruction temporarily when it is fetched or to be sent to main memory
MAR: they store the memory address of the instructions to be fetched or stored by main memory
PC (program counter): they hold the memory address of the next instruction to be processed
Accumulator: they temporarily store the results of operations done in the ALU
List and explain the types of registers
clock speed
Cache size
Number of cores
Factors that affects the CPU performance
is the speed a program operates, measures in hertz or gigahertz(one billion cycles per second), the faster the clock speed the faster instructions are fetched decoded and executed - typical speed for a PC is 2Ghtz and 4Ghtz
How does clock speed affect a CPU performance
Access speed of main memory
Reading from and writing to in main memory is slower than the speed at which the processor can work
Whats one factor that can slow down a computer
Access speed is faster from cache compared to RAM, the more cache a computer has, the more data and instructions can be held in cache and made available more quickly which improves the processor performance
How does cache size affects the performance of a CPU
A high number of cores means parallel processing can take place with more instructions being executed simultaneously
How does number of cores affect a CPU performance
Because the computer isn’t designed to have multiple cores
Explain a reason why a computer won’t work faster with multiple cores
small computers built into an equipment that performs a specific instruction
What are embedded systems
Reliable
Minimal resources
Simple user interface
Sensors that measures external stimuli and react accordingly
Limited operating systems so doesn’t have to be loaded when machine is switched on
Written in machine efficient language so it executes as fast as possible with minimal energy
Program which controls the equipment is held in ROM
Characteristics of embedded systems
Primary storage (RAM, ROM and virtual memory)
Secondary storage ( magnetic devices(HDD), SSD and optical devices
List and give examples on the types of storage
They are storage devices stored away from the computer
What are off line storage devices
It’s the main memory where data or programs that is currently being executed by the processor are stored temporarily
What is RAM
when a program is being executed, it has to be loaded from the hard disk into the main memory so the processor can access its instructions
Need for primary storage
Reading from or writing to hard disk is slower compared to the speed of the processor are
Why doesn’t the processor get instructions straight from hard disk
They temporarily hold data currently being run from the RAM when the RAM has not enough main memory and the data will be swapped between the virtual memory and main memory to be executed because the virtual memory has a slower access speed; although the time used in swapping might be more than the time used in executing
What are virtual memory and uses
RAM volatile while ROM is non volatile
RAM , memory can read or written to while ROM, memory can only be read from
RAM stored data or operating system which is currently in use while ROM stores BIOS/bootstrap loader that loads the operating system or required to start up the computer
Difference between RAM and ROM
Capacity
Durability
Cost
Speed
Portability
Reliability
Factors to consider in a device
That have moving parts so they are susceptible to damage, and vulnerable to magnetic fields, less portable so required for desktop purposes and slow to read from or write to . Alothiugb they can be internal or portable (portable are offline storage devices)
Explain magnetic devices
Has no moving part so less susceptible to damage , not vulnerable to magnetic properties
Quieter
Has no moving part so thin
Lower power consumption
Faster access times
Lighter
Run cooler
benefits of SSD compared to HDD
Magnetic sticks( pen drive)
Magnetic cards(XD AND SD in cameras)
Portable devices
USB
SSD
Examples of solid state
Lasers write data to the disc and read data from it, CDs(CD-RW rewrite able, CD-R recordable, CD- ROM read only), DVDs and blue ray
Has moving part so slower to read from and write to, slower access speed and data transfer speed
Explain optical devices
Expensive
Thinner forms so they can break easily
Disadvantages of SSD
Adv: cheaper and higher capacity
Examples: hard disks and magnetic tape
advantages of magnetic devices and examples
Cheaper and longer life
Advantages of optical devices
moving parts so slower access speed or data transfer speed
Can degrade or become scratched overtime
Disadvantages of optical devices
They send signals to coordinate the fetch execute cycles, decoding instructions and running the fetch execute cycle
What’s the control Unit
