Component 1 Flashcards
What is software
Software is the non-physical layer where all the programs and applications run on.
What are dedicated systems?
Computer systems which are created to carry out one funtion.
What is hardware?
The hardware of a computer makes up the physical components such as the CPU, RAM, mouse etc.
What is a computer?
A computer is a machine that processes data.
What is an embedded system?
An embedded system is a computer which is built into other devices like microwaves. They are a type of dedicated system as they only carry out a few tasks.
What are Pros of an embedded system?
1.More effecient
2.Cheaper
3.Easter to design
What does the CPU do?
The CPU carries out all the instructions given to it by the system and handles all the data.
What factors affect the power of a CPU?
Clock speed, number of cores and cache size
What is Von Neumann architecture?
Von Neumann architecture is how modern computers work. It breaks down how a CPU runs programs and instructions using memory addresses.
What are the 3 main componenets of a CPU?
The CU, ALU and Cache
What does the CU do?
- The Control Unit Coordinates the processor
- Decodes instructions
- Runs the F - D - E cycle
What does the ALU do
- Performs logic and arithmetic calculations.
What is the Cache
It is a small block of very fast temporary memory
What does the cache do?
It stores instructions or data most used or used recently.
What the difference between L1 and L2 cache.
L1 cache is faster, and is in the CPU
L2 Cache is slower but has more storage.
What are the 4 registers?
1.PC (Program Counter)
2.ACC (Accumulator)
3.MAR (Memory Adress Register)
4.MDR (Memory Data Register)
What does the MAR do?
Holds the memory location of the data that needs to be accessed
What does the MDR do?
Holds the data found at the address in the MAR, or holds data which is to be transferred to primary memory.
what does the ACC do?
It is where the intermediate arithmetic and logic results are stored
What does the PC do?
Contains the address of the next instruction to be executed
What does the CIR do?
The CIR is a part of the CU and contains the current instruction during decoding or execution
What happens during the Fetch cycle?
- Copy memory address form the PC to the MAR
- Copy Instructions from the MAR into MDR
- Increment PC to next instruction ready for next cycle
What happens during the decode cycle?
1.Instructions in the MDR is decoded by the CPU
2.CPU might decide to load the next step from the MAR/MDR
What happens during the execute cycle?
- Instructions are performed
- Could be reading, writing or halting a program
What is RAM
RAM is volatile memory and holds the data required for the program which is currently running
Why is RAM used instead of the hard drive
RAM is much faster
What is virtual memory?
Virtual memory is when the RAM is full, a part of secondary storage is used as extra storage for CPU
Why is virtual memory slower?
The data has to be written into secondary storage and back into RAM back and forth.
What is ROM
The ROM is a small chip on the motherboard that is non - volatile, which cannot be written to.
What does the ROM do?
The ROM stores the BIOS and stores all the instructions on how to start the computer. The CPU reads the ROM to perform checks on the system.
What factors affect the CPU performance?
Clock speed, No. Of cores and cache size.
What is OS for?
- Allows for communication with internal and external hardware, vie device drivers.
- Provides UI
- Provides platform for applications to run
- Allows the computer to multi-task, by controlling memory resources/CPU
- Deals with file/disk management
- Manages system security
What is a driver?
A piece of software, wich allows the OS to communcate with intenal hardware or peripherals.
What is the difference between GUI and command line interface?
- GUI for normal users, it is visual
- GUI is simpler for people
- Command line is text based
- Command line is less resource heavy, and can be used to automate processes using scripts.
What is secondary vs primary storage?
- primary is the memory that the CPU can access very quickly, like RAM or caches, it is mostly volatile, but very fast.
- Secondary is the memory where all data is stored when not in used. It is slower but non-volatile
What are different versions of secondary storage?
- HDD - data is stored magnetically in small areas on the disk’s tracks
- SSD - have no moving parts, and use flash memory, so it is faster.
- Optical discs
- Magnetic tapes- for archiving as it has very low cost/GB
What are the pros of HDDs vs SSDs
- SSDs are faster, don’t need defragmenting, shock-proof and silent
- HDDs are cheaper, longer read/write life and usually higher capacity
What are the 3 types of utility software?
- Compression
- Defragmentation
- Encryption
What is Compression software?
- reduces file size permanently/temporarily by removing data
- Compression files take up less space and are quicker to donwload
- .zip or .rar
- Must be extracted before use
What is encryption software?
- Encrypts data to stop third-parties from accessing it.
- To decrypt, a special key is needed, which is then used to bring the data back.
What is defragmentation software?
- Reorganises data on the hard drive, by putting fragmented files back together.
- Moves the files to collect all free space together, to prevent further fragmentation.
Why do we need defragmentation software?
- As files are moved, deleted or changed, small gaps appear on the disk
- So when new files are written, the OS splits it into smaller blocks to fill the gaps. This causes fragmentation.
- This fragmentation makes reading/writing slower.
What is an overflow error?
It is when a number has too many bits, resolve it by storing the extra bit elsewhere.
Which way is multiple and divide when shifting binary
Left is multiply, for every place shifted it doubles
Right is the opposite, so divide.
What is 1 Hexadecimal digit equal to?
- Denary 1-15
- A nibble
Why do programmers prefer Hex?
- Simpler to remember large numbers
- Less chance of input error
- Easier to convert between binary and hex than binary and denary.
What is a character set?
- collections of characters that a computer recognises from their binary representation.
What are 2 examples of character sets?
ASCII and Unicode
What is ASCII?
- A character set in the english speaking world
- Each ASCII character is given a 7 bit code, so it can represent 128 characters, including commands.
How do you work out the size of a text file?
File size = no. of bits per character x no. of characters.
What is colour depth?
The number of bits per pixel
How do you work out the number of colours in a bitmap?
No. of colours = 2^n
Where n = no. of bits per pixel.
What colour depth do most devices use?
24 bit colour depth.
How do you find the file size of an image?
file size = image resolution x colour depth.
What is metadata?
The information stored in an image file, which helps the computer recreate the image on screen from binary data in each pixel.
Includes - file format, height, width, colour depth and resolution.
How is sound stored digitally?
- Sound is recorded by an analogue signal microphone
- This is converted into digital data by analogue to digital converters.
- The process is called sampling.
How does sampling work?
- We sample the amplitude of the wave at regular intervals, once the device has sampled it, the curve is recreated using blocks of data from where each sample was taken.
what is bit depth for sound?
Number of bits available for each sample
How do you calculate the size of a sound file?
file size = sample rate x bit depth x length(seconds)
What are the uses of compression?
- Smaller files take up less space
- Streaming and downloading from the internet is faster as it uses less bandwidth
- Allows web pages to load quicker
- Allows to send the same content with a smaller file size by email.
What are the 2 types of compression?
1.Lossy - Works by permanently remobing data from the file, this limits the number of bits the file needs, so reduces the size.
2.Lossless - makes the file smaller by temporarily removing data to store the file and restores it when opened.
What are the pros of lossy?
- greatly reduces file size
- takes up less bandwidth
- Commonly used
What are the cons of lossy?
- loses data
- can’t be used on text or software files
- Worse quality than original, although usually unnoticable.
What are common lossy file types?
1.JPEG 2.AAC 3.MP3
What are the pros of lossless ?
- data is only removed temporarily
- Can be decompressed
- Can be used on text and software.
What are the cons of lossless?
- smaller reduction in file size.
What are examples of lossless file types?
1. FLAC 2. TIFF 3. PNG
What is a PAN?
A personal area network (PAN) connects electronic devices within a user’s immediate area.
What is a LAN?
1.A Local Area Network, covers a small geographical area on a single site, and connects devices within it.
2.All the hardware for a LAN is owned by the organisation that uses it.
Why use a LAN?
- Sharing files is easier
- Share hardware
- Internet can be shared
- Can install updates all at once
- Communication ischeap and easy
- User accounts can be stored centrally, so anyone can login from anywhere in the LAN.