Computer Architecture Basics

Introduction to Computing Fundamentals

• Information technology encompasses the fundamentals of computing.
• The outline covers computer architecture and operating systems.

Computer Architecture

• Hardware Components: Includes CPU, memory, I/O, and buses.
• Understanding PC Specs: Critical for analyzing computer capabilities.
• Registers: There are 1 registers with instructions.
• Memory: Fundamental unit is 3 decimal digit numbers, maximum size 100 locations.
• Instructions: There are 7 instructions.

Operating Systems

• What is an OS?: The software that manages computer hardware and software resources.
• OS Functions: Multitasking, virtual memory, file systems, window systems, and microcomputer operating systems are key functions.
• Microcomputer operating systems: Details on different types are discussed.

Basic Computer Facts

• Memory: Basic unit is a 3-digit decimal number, maximum size 100 locations.

Computer Hardware

• Computer hardware is the physical components of a computer system for input and output.
• The Von-Neumann architecture is a key model representation. This example shows the CPU (Control Unit, Arithmetic/Logic Unit), and Memory Unit.

Computer Components

• Processor (Under the heatsink)
• Motherboard (With ports)
• RAM (Memory)
• Storage Device (Optical and hard drive)
• Graphics card
• Power Supply (Converts electricity)

A "Real" Computer

• A diagram depicts the CPU's components including the Instruction Counter and Registers, along with Memory and input devices (Keyboard, Mouse) and output devices (Monitor, Printer).

Intel Pentium 4 Answers

• Memory: An 8-digit binary number is a byte. 32 bits = 4 bytes. RAM memory size typical is between 128 MB– 1 GB.
• Registers: About 50 registers of various types.
• Instructions: About 500 instructions.

Binary Computers

• Real computers do not store nor calculate with 3-digit decimal numbers.
• A bit has two states: 0 and 1, (TRUE and FALSE).
• Bits are easier to implement in machines (e.g., light bulb on/off; high/low voltage).

Interpretation of Decimal Numbers

• Decimal numbers (e.g., 379) are interpreted as a sum of powers of 10. (3 x 10² + 7 x 10¹ + 9 x10⁰)

Interpretation of Binary Numbers

• Binary numbers interpret the sum of powers of 2. ( e.g., 11011=1x2⁴ + 1x2³ + 0x2² + 1x2¹ +1x2⁰ = 1 x 16 + 1 x 8+ 0 x 4+1x2+ 1x1 = 27)

CPU Function

• The CPU is the central processing unit.
• The CPU ticks very fast, e.g., 1.6 GHz which is (1.6 trillion ticks per second).
• Activities are synchronized to start on a clock tick.
• Instructions Execution is automatic (find memory address, retrieve, decode, fetch, execute, store).

CPU-Memory Interaction

• The CPU and memory interact through address lines and data lines.

CPU Issues an Address

• The CPU issues an address (e.g., 00110010) to access a specific memory location (50).

Making the Data Available

• Memory provides the requested data (e.g., 127) to the CPU at memory location 50.

CPU Characteristics

• Family: Determines the set of instructions (e.g., Intel 80386, 80486, Pentium, Pentium II, Motorola 68030).
• Clock Speed: Measures the CPU's speed in GHz (e.g., Pentium: 500 MHz - 2.2 GHz).
• Data bus width: The amount of data that can be processed at once (e.g., 80486-32 bits, Pentium 64 bits).
• Address bus width: The amount of memory that can be installed using bits. (e.g., LMC 3 decimal, Pentium 32 bits, Itanium 64 bits).

Expressing Memory Capacity

• Memory is measured in bytes (8 bits).
• A byte can store binary numbers from 00000000 -11111111.
• Multiple bytes use prefixes like kilo, mega, and giga for larger values.

Semiconductor Memory

• RAM (Random Access Memory): Accessed equally fast, but loses data without power. Has two types: Static (SRAM) and Dynamic (DRAM).
• ROM (Read-Only Memory): Retains data even without power. Useful during startup.

Hard Disks and Floppies

• Slower than main memory.
• Bits are stored as magnetic fields of different polarity.
• A head (read/write) reads/writes data. The disk rotates.
• Disks are divided into tracks (of different radial distance), then into sectors.

Hard Disk Geometry

• Heads move back and forth.
• System waits for the desired sector to pass.
• Data is read or written.

CD-ROMs

• Slower than hard disks.
• Data is encoded by burning "pits" on the surface (read by a laser).
• Holds up to 650 MB of data.
• CD-ROM drive's speed is measured in multiples of 150 KB/sec (e.g., 4X drive is 600 KB/sec, 20X = 3000 KB/sec).

DVD (Digital Video Disk)

• Newer improved CD-ROM.
• Smaller, denser "pits" with two layers.
• Holds up to 17 GB of data.

Keychain Drives

• Attaches to a USB port.
• Holds 16 MB to 2GB of data.
• Using "flash memory" (special kind of ROM). This memory can be rapidly erased and re-recorded.

I/O Devices

• Input: Keyboard, mouse, hard disk, floppy disk
• Output: Printer, screen, speakers

Computer Displays

• Pixels are displayed in different colors.
• Screen resolution is measured in pixels (e.g., 640x480, 1024x768).
• Color information is stored, then converted to video signal. Color per pixel can be between 256 to 16 million colors).

Buses

• One set of wires connects all devices and CPU.
• Information transport is shared (public bus).
• Modern PCs use a bus to connect CPU and I/O devices.
• Buses allow easy addition/replacement of I/O devices. Examples: ISA, PCI, PCMCIA, IEEE 1394.

A Simple Bus Architecture

• CPU interacts with memory and I/O devices via the bus
• Shows the general path between devices connected by a bus.

Cache Memory

• Cheap main memory is slower than the CPU.
• Solution: Automatically keep copies of frequently used memory locations in fast but expensive cache memory.

A Modern PC Architecture (Simplified)

• Diagram shows the CPU, cache, RAM, bus, video controller, and disk controller, including faster and slower channels for connections.

Summary: A Modern PC

• Processor: Pentium (500 MHz - 3.6 GHz).
• Main Memory (RAM): 64 MB - 4 GB.
• Floppy Drive: 1.44 MB.
• Hard Drive: 10 GB– 500 GB.
• Graphics: 640x480– 2048x1536, 256–16 million colors.
• Video Memory: 32–256 MB.

Types of Software

• System Software: Operating systems, programming languages, database systems
• Application Software: General office tasks, accounting, design, factory automation, and more.

Operating Systems - Examples

• DOS
• Windows (95, 98, NT, 2000, XP)
• Mac OS X
• Unix
• Linux

Operating System Functions

• Allocates memory (e.g., file system, virtual memory)
• Handles processor time (e.g., multitasking, multiprocessing).
• Manages input/output devices (e.g., printer, keyboard)
• May also provide other capabilities useful for users and programs (e.g., GUI, fonts, network protocols).

Operating System Illusions

• Multitasking: The illusion of many programs running at once.
• Large Memory: The illusion of having unlimited memory (virtual memory).
• File Systems: The illusion of files and directories on disks.
• Windows and Menus: The illusion of graphical user interface (GUI) where the screen's pixels are manipulated to appear as windows, menus.

Multitasking Issues

• Cooperative Multitasking: Task needs to explicitly pass control to the OS.
• Preemptive Multitasking: OS interrupts tasks when I/O is requested or time limit is exceeded.

Virtual Memory

• Copies data to hard disk when not in use for fast access to all data.
• Main memory and hard disk work collaboratively. Memory location needed and not in memory is retrieved by the OS to the memory.

File Systems

• Tracks and sectors are broken down to organize data on disks.

Windows and Menus

• GUI relies on pixel manipulation to create windows and menus.
• OS handles mouse clicks and other input to create the illusion.

Microcomputer Operating Systems

• DOS: Text-based, no multitasking.
• Windows: Windows, cooperative multitasking, filenames restricted to 8 characters.
• Windows 98: Improved multitasking, large filenames, built-in network capabilities.

Microcomputer Operating Systems (Cont'd)

• Windows NT: Full multitasking and memory management (e.g., Windows 2000, XP).
• UNIX (including Linux): Great memory management, multitasking, complex text interface.
• Mac OS X: Based on UNIX, easy-to-use, only on Macintoshes.

Selecting an Operating System

• Compatibility with existing software
• Large base of compatible software
• Reliability (crash frequency)
• Hardware availability
• Speed
• Ease of learning and use
• Ease of installation
• Cost factors

Test your knowledge on the fundamental concepts of computer architecture and memory. This quiz covers various topics, including the CPU, memory units, and storage devices. Perfect for beginners looking to understand how computers function.