Chapters 1-3 Part I – Computer Organisation and Architecture in [B2] Flashcards
What are the four main functions of a computer system?
Central processing unit (CPU): Controls the operation of the computer and performs its data processing functions; often simply referred to as processor.
Main memory: Stores data.
I/O: Moves data between the computer and its external environment.
System interconnection: Some mechanism that provides for communication among CPU, main memory, and I/O. A common example of system interconnection is by means of a system bus, consisting of a number of conducting wires to which all the other components attach.
What is the general structure of a computer system?
Central Processing Unit (CPU):
Often considered the “brain” of the computer, the CPU executes instructions stored in memory. It includes an Arithmetic Logic Unit (ALU) for mathematical and logical operations and a Control Unit for managing the execution of instructions.
Memory:
Memory is used to store data and instructions that the CPU needs during program execution. The two main types are:
RAM (Random Access Memory): Volatile memory used for temporary storage. It loses its contents when the power is turned off.
ROM (Read-Only Memory): Non-volatile memory that stores firmware and essential system instructions.
Storage Devices:
Storage devices, such as hard drives, solid-state drives, and optical drives, provide long-term storage for data and programs. Unlike memory, storage retains its content even when the power is off.
Input Devices:
Input devices allow users to interact with the computer. Common input devices include keyboards, mice, touchscreens, and scanners.
Output Devices:
Output devices display or produce results from the computer. Examples include monitors, printers, and speakers.
Motherboard:
The motherboard is the main circuit board that houses the CPU, memory, and other essential components. It provides the electrical connections and buses that allow these components to communicate.
Bus System:
Buses are communication pathways that transfer data between components such as the CPU, memory, and peripherals. Common buses include the system bus, data bus, and address bus.
Peripheral Devices:
Peripheral devices are additional hardware components that can be connected to the computer. Examples include printers, external drives, and network adapters.
Operating System:
The operating system (OS) is software that manages hardware resources, provides an interface for user interaction, and facilitates the execution of applications. Examples of operating systems include Windows, macOS, and Linux.
Application Software:
Application software consists of programs designed to perform specific tasks or functions for users. Examples include word processors, web browsers, and graphic design software.
Network Interface:
Network interfaces enable the computer to connect to networks, facilitating communication and data exchange with other devices.
Power Supply:
The power supply unit converts electrical power from an outlet into a form suitable for the computer’s components. It provides the necessary voltage and current to power the system.
These components work together, with the CPU at the center, to execute programs, process data, and perform various tasks. The motherboard serves as the central hub for connecting and coordinating these components, and the operating system provides the software infrastructure for managing and controlling the hardware resources. The interaction between hardware and software is a fundamental aspect of the computer system’s operation.
What are the main concepts of IAS structure?(Also referred to as the von Neumann architecture)
Data and instructions are stored in a single read–write memory
The contents of this memory are addressable by location, without regard to the type of data contained there.
Execution occurs in a sequential fashion (unless explicitly modified) from one instruction to the next.
An overview of computer components
Central Processing Unit (CPU)
Memory (RAM, ROM)
Storage Devices
Input Devices:
Output Devices:
Motherboard
Bus System
Operating System
Application Software
Power Supply
Network Interface
Understanding basic instruction cycles (with interrupts)
Concepts about interrupts:
- Various classes
- How to handle interrupts
Classes of interrupts
Program:
* Interruptions are generated by an instruction
e.g., arithmetic overflow, division by zero, attempting to perform
unknown instructions, error addressing
– unknown instructions – illegeal machine instruction
– error addressing – reference outside a user’s allowed memory space
Timer:
– generated by a timer within the processor, this allows the OS to perform certain
functions on a regular basis
I/O:
– generated by I/O controller, to signal normal completion of an operation, request service from the processor, or to signal a variety of error condition
Hardware failure:
– generated by a failure such as power failure or memory parity error
How to handle interrupts:
If an interrupt is pending, the processor:
* It suspends execution of the current program being executed and saves its context, i.e., saving the address of the next instruction to be executed and any other data relevant to the processor’s current activity.
* It sets the program counter to the starting address of an interrup handler routine.
An overview of interconnection
The collection of paths connecting the various modules is called the interconnection structure. The design of this structure will depend on the exchanges that must be made among modules.
■ Memory: Typically, a memory module will consist of N words of equal length. Each word is assigned a unique numerical address (0, 1, c , N-1). A word of data can be read from or written into the memory. The nature of the operation is indicated by read and write control signals. The location for the operation is
specified by an address.
■ I/O module: From an internal (to the computer system) point of view, I/O is
functionally similar to memory. There are two operations; read and write. Further, an I/O module may control more than one external device. We can refer
to each of the interfaces to an external device as a port and give each a unique address (e.g., 0, 1, c , M-1). In addition, there are external data paths for the input and output of data with an external device. Finally, an I/O module may be able to send interrupt signals to the processor.
■ Processor: The processor reads in instructions and data, writes out data after processing, and uses control signals to control the overall operation of the system. It also receives interrupt signals.
The preceding list defines the data to be exchanged. The interconnection structure must support the following types of transfers:
■ Memory to processor: The processor reads an instruction or a unit of data
from memory.
■ Processor to memory: The processor writes a unit of data to memory.
■ I/O to processor: The processor reads data from an I/O device via an I/O
module.
■ Processor to I/O: The processor sends data to the I/O device.
■ I/O to or from memory: For these two cases, an I/O module is allowed to exchange data directly with memory, without going through the processor, using direct memory access.
Over the years, a number of interconnection structures have been tried. By far the most common are (1) the bus and various multiple-bus structures, and (2) pointto-point interconnection structures with packetized data transfer. We devote the
remainder of this chapter for a discussion of these structures.