J277 OCR GCSE Computer Science Paper 1: Computer Systems

Flashcards based on the provided lecture notes on computer systems.

What is the purpose of the central processing unit (CPU)?

To process data instructions by constantly performing the fetch execute cycle.

Where are instructions fetched from in the fetch execute cycle?

RAM

Which specific register stores instructions in the fetch execute cycle?

Memory Data Register (MDR)

Which component decodes instructions in the execute stage of the fetch execute cycle?

Control Unit

Which component performs arithmetic or logical calculations?

Arithmetic Logic Unit (ALU)

What are the functions of the control unit?

Sends control and timing signals to the ALU and other components, manages data flow, and decodes instructions.

What calculations does the Arithmetic Logic Unit (ALU) perform?

Mathematical calculations, logical operations, and binary shifts.

What are registers?

Temporary storage spaces for one piece of data or one address at a time.

What is cache memory used for?

Temporarily stores frequently accessed data and is split into three levels.

What does the program counter (PC) store?

Stores the address of the next instruction to be fetched from RAM.

What does the memory address register (MAR) store?

Stores the address of the current instruction to be fetched from RAM.

What does the memory data register (MDR) store?

Stores the instruction or data transferred from the RAM address.

Where are the results of executions stored?

The Accumulator

What is the key feature of Von Neumann architecture?

Data and program instructions are stored in binary format in the same memory (RAM).

What two parts are instructions split into?

Opcode and operand

What is the opcode?

The action to perform, such as add, input, or load.

What is the operand?

Can refer to data (a value) or an address (location in RAM).

What is clock speed?

The measure of how many fetch execute cycles the CPU can perform per second, measured in gigahertz.

How does clock speed affect CPU performance?

A higher clock speed means more fetch execute cycles can be processed per second, improving performance.

How does a larger amount of cache memory improve CPU performance?

It can store more frequently accessed data, improving performance.

What is a core?

A complete set of CPU components that can perform its own fetch execute cycle.

Why should a CPU with more cores have a higher performance?

It can process more instructions at the same time.

What is an embedded system?

Built into a larger device for specific, repeated tasks, often using a microprocessor on a single circuit board.

Where is the operating system and software located in an Embedded System?

The operating system and software is built into the ROM, also known as firmware.

What is primary storage?

High-speed internal memory that the CPU can directly access (RAM and ROM).

What is Random Access Memory (RAM)?

Volatile memory that temporarily stores instructions and data for currently running programs; data is lost when power is off.

What is Read Only Memory (ROM)?

Non-volatile memory that stores startup instructions (bootstrap program) to load the operating system; data is saved even when power is off.

What is virtual memory?

Using the hard drive or solid-state drive as an extension to RAM when RAM is close to full capacity.

What is secondary storage?

Non-volatile storage used for the long-term storage of files and data.

What are the three types of secondary storage?

Magnetic, optical, and solid state.

What is one way to remember the six characteristics of secondary storage?

CSNUS mnemonic PC Card.

What is Access speed?

How quickly data on a secondary storage device can be written to or read from.

What are benefits of optical discs?

They are cheap to manufacture, lightweight, and portable.

How does a hard disk drive operate?

A read/write head moves across tiny individual sections of a magnetized spinning disc.

What are some examples of solid state storage?

Solid state drives, USB sticks, and SD cards.

What are the superior characteristics of solid state storage?

They contain no moving parts, allowing for direct and very fast data access.

What is a bit?

A single binary digit.

What is a nibble?

Four bits.

What is a byte?

Eight bits.

Why is all data stored in binary?

Computer systems consist of billions of tiny transistors which act as switches with two states (on and off, represented by 1 and 0).

What is the difference used to convert data storage units?

1,000

In number systems, what is the base?

The number of unique digits that can be represented. Also, refers to difference in place values.

What digits does Binary use?

Zero and One

What digits does Denary use?

zero to nine

What digits does Hexadecimal use?

zero to nine and then a to f

How many bits does each Hexadecimal Digit Repersent

A hexadecimal digit represents four bits, which is a nibble.

Why is Hexadecimal easier to read

Because hexadecimal uses fewer digits to represent the same number in binary, making it easier to read and write with a lower likelihood of mistakes.

What is the Least Significant Bit

The bit furthest to the right of a binary number. This represents the smallest binary value in the number, which will always represent One.

What is the Most Significant Bit

The bit furthest to the left of a binary number. This represents the largest binary value in the number.

What is a Character Set

A character set is a collection of all the characters a computer can represent. A table maps or matches each character to a unique binary code.

What type of Characters are mapped by a Character Set?

Letters, numbers, symbols, control characters (like backspace and tab), and in some sets, emojis.

What does ASCII stand For?

American Standard Code for Information Interchange

What is ASCII

A character set that uses one byte 8 bits to represent each character, allowing for a total of 256 different characters.

What is Unicode

A character set that uses two bytes 16 bits to represent each character, allowing for 65,536 possible characters. It is the most popular character set.

What is the file size of a text file?

The amount of space requires to store text on a computer

What are Bitmaps

Most computer images are bitmaps, which use a series of square blocks called pixels arranged in a grid.

What is Resolution?

The total number of pixels in an image (width times height).

How does Resolution Affect an Image

It affects image quality and file size.

How is quality and size effected by resolution?

The higher the resolution, the better the image quality, and the larger the file size.

What is Color Depth

The number of bits that are used to represent each pixel's color.

What is Metadata

Additional data about a file to provide further context (e.g., height, width, color depth, resolution, geolocation, date created, file type, file name).

How is sound Digitally Recorded

The amplitude (height) of the analog sound wave is measured and recorded in binary at specific intervals.

What is Sample Rate

How many times per second the amplitude of a sound wave is measured (measured in hertz).

What is Bit Depth

The number of bits available to represent each sample, representing the range of amplitude values or unique sounds available for each sample.

What is Compression?

The use of an algorithm to reduce the size of a file.

What is Lossy Compression?

Decreases file size by permanently removing data, which may result in a noticeable loss of quality.

What is Lossless Compression?

Reduces file size without permanently removing any data, so the original file can be fully restored without any loss of quality.

What is a Network?

A set of computers connected together to share data and resources.

What is a Local Area Network LAN

Connects computer systems that are situated geographically close together.

What is a Wide Area Network WAN

Contains computer systems situated geographically distant to each other, possibly across a country or the world.

What is Bandwidth?

The amount of data that can be transmitted per second (usually measured in megabits per second or gigabits per second).

What is Latency

The delay in the transmission of data (often caused by distance or network congestion), measured in milliseconds.

What is the Internet

A global connection of computer networks that uses servers to store and present websites, emails, and files to client devices when requested.

What do Web Servers do?

Display web pages to clients when their browser requests it.

What do Printer Servers do?

Queue print jobs that clients request and send documents to the correct printer.

What do Email Servers do?

Filter spam and send and store emails so they can be retrieved by clients when requested.

What does a Client Server do

Makes requests to a central server for data or resources; the server processes the request and returns a response.

What is the definition of a peer to peer network

There is no central server.

What is a wireless access point?

Provides a link between wired and wireless networks and creates a wireless local area network (WLAN) using radio waves.

What does a Router do?

Directs data packets between different networks using a routing table with IP addresses to determine the best route.

What does a Switch do?

Connects devices on a LAN and forwards data packets directly to the correct device using its unique MAC address.

What is a Network Interface Controller or NIC

An internal piece of hardware required for a device to connect to a network.

What is Transmission media?

The physical or wireless methods used to transfer data between devices on a network.

What does the Domain Name System DNS do?

Uses servers to match domain names to IP addresses so that web browsers can locate, request, and access web pages.

What is Cloud Computing

A network of servers accessed on the Internet to provide services.

What is Network Topology

The layout of computer systems (nodes) on a network.

What is a star network topology?

Has all nodes connected to a central switch.

What is a mesh network topology?

Has nodes connected to all, or most, other nodes.

What is a Wired Network?

Transfers data across a physical connection using transmission media such as Ethernet cables. It requires a network interface controller within each device.

What is a Wireless Network?

Uses radio waves to transmit data through the air (e.g., Wi-Fi and Bluetooth).

What is Encryption?

The process of scrambling data into an unreadable format using an encryption key so that attackers cannot understand it if intercepted during transmission.

What is an IP Address?

Identifies a device's logical location on a network. It is used by routers to route data across the Internet.

What is an MAC Address?

A unique physical address assigned to each device's network interface controller (NIC). It is used by switches to identify and communicate with devices on a local area network.

What is a Protocol?

A set of rules that allow computers to communicate and exchange data with each other across networks such as the Internet.

What is TCP/IP?

Reliably exchanges data between devices on the Internet; TCP breaks data into packets and ensures they are reordered correctly; IP handles addressing and routing.

What is HTTP

A web browser uses it to request and access a web page from a web server.

What is HTTPS

A more secure version of HTTP that uses encryption.

What is FTP

Used to transfer files across a network and upload/download files between clients and a server.

What is SMTP

Used to send emails to email servers and between email servers.

What is POP

Used to retrieve and store emails from an email server onto a computer (emails are deleted from the email server).