Computer Organization: Binary, Interrupts, Polling

Computer Organization - Binary Representation

• All data and instructions in computer systems are stored as binary digits (bits), which have values of 1 or 0.
• Eight bits form a byte.
• Bytes are used to represent characters, file sizes (e.g., 12MB), and connection speeds (e.g., 50Mbps).

Interrupt

• Allows a higher-priority task to interrupt a current CPU job temporarily.
• Can be triggered by hardware or software.
• Used to signal that a client needs access to a server in a multi-access system.
• Used to signal a peripheral needing service (e.g., printer).
• Used to signal software errors or problems (e.g., low battery).
• CPU handles interrupts by suspending current tasks, activating an interrupt handler, and servicing the interrupt request.
• An interrupt register (IR) stores the location of the interrupt-handling code in memory.

Polling

• A technique that allows a unit to check the status of another unit at regular intervals.
• Efficient use of CPU time when CPU is not busy.

Handshaking

• The exchange of signals/messages between devices to confirm readiness for data exchange.
• Devices use signals to establish parameters, protocols, and certificates for data transmission.

Buffer

• Temporarily holds data to compensate for speed differences between devices.
• Peripherals are often slower than the CPU.
• The buffer allows the CPU to complete other tasks while the peripheral processes the data.

Paging

• A memory management technique used in virtual memory.
• Divides memory into pages which can be swapped between RAM and secondary storage.
• Improves the effective amount of RAM by allowing programs larger than RAM to be run.

Virtual Machines

• Emulate other operating systems, hiding the host machine's environment.
• Allow software to be executed on different platforms (portability).
• More practical and cost-effective than testing software on multiple physical machines.

Voice over IP (VoIP)

• Audio (and potentially video) transmitted over the internet.
• Requires broadband internet connection.
• Can be integrated with office computers, collaborative devices (webcams, desk endpoints), and phones.
• Resources include bandwidth (and quality considerations).
• Routers must be capable of handling VoIP traffic for optimal performance.

Memory Management

• Operating systems (OS) allow multiple programs to share memory by assigning separate memory areas to each.
• OS manages memory isolation for each program to avoid conflicts.
• Paging can occur if shared memory storage gets full.
• CPU management prioritizes tasks for efficient use.

Primary Memory (RAM)

• Stores data and instructions active in a computer.
• Directly connected and communicates with the processor.
• Includes RAM (static and dynamic), and cache.
• Enables the fetch, decode, and execute CPU cycle.

Secondary Storage

• Provides affordable, mass-storage permanence for data that doesn't need constant access.
• Types include direct and sequential access.

Batch Processing

• Executing multiple programs together as a group.
• Programs wait in sequence to be executed.
• No user interaction during processing.
• Can be inefficient and not suited for all applications.

Multiprogramming

• Running multiple programs concurrently, but only executing one at a time.
• Minimizes CPU idle time, improves system utilization.

Multitasking

• Similar to multiprogramming, but tasks are smaller and completed quickly.
• Uses CPU time-sharing.

Multiprocessing

• Using multiple CPUs to execute tasks simultaneously.
• Improves processing speed and performance on complex tasks.

Multithreading

• Allows a program to execute several parts concurrently (called threads).
• Avoids thread interference.

Swapping

• Technique of temporarily moving code from RAM to secondary storage.
• Allows more programs/processes to be in RAM than the physical memory allows.
• Can result in less efficient operations.

Paging

• Mechanism that implements virtual memory.
• Allows modern OS to use secondary storage as if it were additional RAM.
• Excessive paging (swapping) causes inefficiencies and performance issues.

Control Systems

• Device systems that operate automatically.
• Includes sensors for feedback information and actuators for control.
• Examples include door openers, and other automated systems.