(section 1) knowledge organiser computing

Question 1

hardware

Answer 1

physical components in a computer system

Question 2

software

Answer 2

programs

Question 3

embedded system

Answer 3

computer system built into other devices, usually control systems

Question 4

4 CPU components?

Answer 4

alu, registers, cache, cu

Question 5

3 factors affecting CPU performance?

Answer 5

Number of cores, clock speed, cache size

Question 6

main idea of von neumann architecture

Answer 6

data and instructions are both stored in the same memory

Question 7

PC

Answer 7

holds the memory address of the instruction for each cycle

Question 8

MAR

Answer 8

holds any memory address about to be used by the CPU. the address could point to data or an instruction

Question 9

MDR

Answer 9

holds the actual data or instruction, either fetched from memory or waiting to be written to memory

Question 10

accumulator

Answer 10

stores intermediate results of calculations in the ALU

Question 11

what happens during the fetch cycle?

Answer 11

Memory is copied from the PC to the MAR. // The instruction is copied from memory into the MDR. // Program counter is incremented to point to the next instruction.

Question 12

What happens during the decode cycle?

Answer 12

Instruction in the MDR is decoded by the control unit. // Control unit prepares for the next step.

Question 13

What happens during the execute cycle?

Answer 13

Decoded instructions are carried out.

Question 14

What are the characteristics of RAM?

Answer 14

Volatile memory. // Easy to read/write to. // Programs and data are copied into RAM while in use. // Slower than CPU cache, but still faster than secondary storage.

Question 15

virtual memory

Answer 15

If RAM is used up, some data of the program being run is moved to a location in secondary storage called virtual memory. This involves swapping instructions currently being executed and instructions not currently being executed to and from RAM and secondary storage. Data transfer is slow on secondary storage, so this slows down the computer’s performance.

Question 16

Secondary storage

Answer 16

Non-volatile storage where program and data are kept for later use.

Question 17

Characteristics of HDD?

Answer 17

moving parts // stores data magnetically on metal disks // can be noisy

Question 18

characteristics of ssds?

Answer 18

no moving parts // use flash memory for faster read/ write times // usually silent/quiet

Question 19

What are the 4 types of external storage?

Answer 19

1. flash drives and memory cards (ssd)
2. optical disks
3. magnetic tape
4. external hdd/ ssd

Question 20

advantages and disadvantages of optical disks?

Answer 20

pos: portable, relatively cheap, long term storage
neg: limited storage space, fragile, becoming obsolete, slow read/write speeds

Question 21

advantages and disadvantages of flash drives/ memory cards?

Answer 21

pos: portable, fast read/write, durable, easily compatible
neg: easily lost, low security, more expensive per gb

Question 22

advantages and disadvantages of external hdds?

Answer 22

pos: huge storage capacity, cheaper per gb, can last for longer
neg: bulky, noisy, easily damaged, slower than ssd

Question 23

advantages and disadvantages of external ssds?

Answer 23

pos: portable, silent, energy-efficient, extremely fast
neg: more expensive per gb, smaller storage capacities than hdds

Question 24

advantages and disadvantages of magnetic tapes?

Answer 24

pos: huge capacities, long lifespans, cheap per gb
neg: heavy, bulky, takes up a lot of physical space, very slow data access, requires expensive tape drivers

Question 25

five functions of the OS

Answer 25

1. peripheral management and drivers
2. providing a user interface
3. memory management and multitasking
4. file and disk management
5. user management

Question 26

Peripheral management and drivers

Answer 26

1. Communicates with internal hardware, and peripherals, using drivers.
2. Chooses correct drivers for connected hardware on startup
3. Installs drivers for hardware and updates drivers automatically

Question 27

Providing a user interface

Answer 27

Allows users to interact with a computer.
Graphical user interfaces (GUIs) have windows, icons, menus and pointers, and are designed for everyday users.
Command line interfaces allow users to directly communicate with the computer system. They are text-based and use fewer system resources, and are for more advanced users.

Question 28

Memory management and multi-tasking

Answer 28

1. Moves application data to main memory when in use and removes it when it’s no longer needed.
2. Allocates memory addresses so apps don’t interfere with or overwrite each other.
3. Divides CPU processing time between tasks to complete them efficiently.
4. Uses memory buffers to store data until other components or processes are ready.

Question 29

File and disk management

Answer 29

1. Organizes files into a hierarchical order of folders
2. Deals with naming, editing, saving and deleting of files
3. Splits the hard disk into sectors and decides where files are written to
4. Maintains the hard disk with utility software.

Question 30

User management

Answer 30

1. Controls which and how many users can access the computer system.
2. Grants users access to specific data and resources
3. Uses anti-theft measures to prevent access for other users.

Question 31

What is utility software?

Answer 31

Software that is designed to help maintain a computer system.

Question 32

What does defragmentation software do?

Answer 32

It reorganizes a HDD by putting related data back together. This speeds up reading/ writing files as the read/write head no longer has to move as much.

Question 33

What causes the HDD to fragment?

Answer 33

1. Files are stored in available space on the hard disk.
2. When files are moved, changed size or deleted, small gaps appear on the disk.
3. When writing new files to the hard drive, the OS splits them into smaller blocks to fill the gaps.
4. Defragmentation software puts the fragmented files back together. It also groups free space to prevent further fragmentation.

Question 34

What is compression software?

Answer 34

1. It reduces the size of files temporarily or permanently by removing data from them.
2. Compressed files take up less space and are quicker to upload/ download.
3. Compressed files need to be extracted before they can be used.

Question 35

What is encryption software?

Answer 35

Encryption software scrambles data so that it cannot be read by third parties. A key which only the intended readers have is needed for the software to be unscrambled, so encrypted data is secure even if it is stolen. Strong encryption makes it impossible to find the key through brute force methods.