Temperature and Sensor Functionality Quiz

Computer Science Study Notes

• The Central Processing Unit (CPU) is a vital component in modern computer systems.
• It is often implemented as an integrated circuit on a single microchip.
• The CPU is responsible for executing all instructions and processing data in a computer application.
• Early computers required manual data input; the stored program computer concept, developed in the mid-1940s by John von Neumann, revolutionized this.
• The von Neumann architecture's fundamental concepts include a Central Processing Unit (CPU) that directly accesses memory for programs and data.
• Stored programs are sequences of instructions executed sequentially.
• The Arithmetic Logic Unit (ALU) is incorporated within the CPU, performing mathematical operations (addition, subtraction, multiplication, and division) and logical operations.
• Multiple ALUs are possible in a single computer, each handling specific functions.
• System buses (connections) transport data around computers.
• Address Bus carries memory addresses between memory and CPU.
• Data Bus carries data between memory and CPU/input/output devices.
• Control Bus carries signals from the control unit to other components in the computer.
• Crucial components of a CPU include the Control Unit (CU), Arithmetic Logic Unit (ALU), Memory Address Register (MAR), Memory Data Register (MDR), Program Counter (PC), and others.
• Random Access Memory (RAM) is a component of the computer's memory unit.
• RAM stores instructions and data needed for processing during regular operation.
• Data and programs from the hard disk drive are temporarily stored in RAM.
• The read/write operations in RAM are considerably faster than those on the hard disk drive.
• The contents of RAM are lost if the computer is powered off.
• Registers are fundamental components within the von Neumann architecture.
• Current Instruction Register(CIR) stores the current instruction being processed.
• Accumulator (ACC) stores data temporarily during ALU calculations.
• Memory Address Register (MAR) stores the memory address being read or written to.
• Memory Data (Buffer) Register (MDR) temporarily holds data read from memory or about to be written.
• Program Counter (PC) stores the address of the next instruction to be processed.
• The Control Unit (CU) coordinates the entire process by fetching instructions from memory, decoding them, directing the ALU for operations, and coordinating the input/output devices.
• The Fetch-Decode-Execute cycle is fundamental to how modern computers function.
• The Control Unit (CU) fetches an instruction, decodes it, and sends signals through the control bus.
• Other important components in the CPU are the MAR, MDR, and PC, along with the ALU.
• Clock speed, cache memory, and cores are auxiliary elements that significantly affect a computer's overall operating speed.
• Clock speed measures the frequency of electrical pulses in the CPU, measured in gigahertz (GHz).
• Higher clock speeds generally lead to faster processing.
• Cores are separate processing units in a CPU; more cores allow for parallel processing, improving performance.
• Cache memory is a high-speed memory located within the CPU, holding frequently used data and instructions.
• Instruction Set: Operations are made up of opcodes and operands.
• Opcodes give specific instructions for the CPU to execute; different companies/processors have their own instruction sets.
• The opcode and operands are stored on a hard disk and then loaded.
• The opcode gives the CPU a specific precise job related to what is executed.
• An operand is data required for the specific job as detailed by the opcode and may be a data item or an address location.
  • Example (X86 Instruction Set, an early version):
    • Load (opcode 10), Add (opcode 11), Store (opcode 12)
• Embedded Systems use a combination of hardware and software to perform specific tasks.
• Vending Machines and Lighting Systems present embedded systems that need specific functionality within the device.
• Embedded systems typically are low-power devices using batteries.
• Embedded systems can be programmed or non-programmable.
• Some embedded systems can be upgraded via programming and others can’t and require replacements if new data needs to be implemented..
• Input Devices: Keyboards, optical mice, touchscreens, scanners, barcode readers, digital cameras
• Output Devices: Monitor, touchscreens, projector, printer, speakers, actuators
• The choice of output device depends on the intended use of the processed data.
• A touch screen is made of glass and is used to control the device via touch.
• Different types of touch screens exist, such as resistive, capacitive, and infrared.
• Capacitive touch screens function by detecting the change in electrical field produced by a finger touching the screen.
• Resistive touch screens apply pressure to change the resistance, or increase in voltage.
• Infrared touch screens interrupt an infrared beam when a touch occurs to establish the location.
• Scanners convert images or text on paper into digital format for editing or manipulation.
• Optical character recognition (OCR) is a feature of some scanners converting scan converted images into editable texts.
• 3D scanners work in 3 dimensions in contrast to 2D and use reflected laser light to capture the images/3D model from an object
• Barcode Readers: Use infrared light to convert bar codes into digital values.
• The stored info/data within a barcode is checked and retrieved (typically), from a database during the 'purchase process'.
• Digital Cameras/Webcams capture a view of the scene as a digital image.
• Microphones convert sound into digital information used for videoconferencing.
• Primary Memory is volatile (RAM) or non-volatile (ROM), for temporary or permanent stored data respectively; it can be accessed directly by the CPU.
• Secondary Storage (HDD, SSD, Optical Disks) store large quantities of data but the access time to retrieve info is usually slower than Primary Memory. The HDD and SSD are non-volatile which implies the data is kept even if the device is turned off.
• Virtual memory uses part of a HDD/SSD to temporarily store data, giving the illusion of unlimited RAM.
• Disk thrashing is the negative performance impact from repeatedly moving data in and out of a hard disk.
• Cloud Storage stores data remotely, usually on many remote servers, and is accessed through a network connection.
• Important factors for selecting memory include access time, capacity, cost, and physical form-factor (portable or fixed).
• Different types of memory are tailored for different applications (e.g., high-speed in-memory database vs storage backup for long-term data preservation).
• Various computer/network components such as routers, modems, and network interface cards (NICs) facilitate network communication.
• Routers enable networks to communicate via converting data format and protocols, also ensuring data packets are correctly routed to the destination.
• A LAN (Local Area Network) uses unique MAC addresses for device identification (computers, printers).
• Each device has a Unique MAC address created either in the factory or by the company that manufactured the device.
• IP addresses are given by the ISP and are needed for network communication outside of a LAN.
• A device’s unique IP address is commonly changed while on a network, but this may vary.
• A Static IP address is one which is permanently assigned to the user/device.
• A Dynamic IP address is one which is often assigned temporarily to a user/device (the address varies each time the device connects to a network).