Chapter 2

Module 2A Inside the System Unit Module 2B Data Storage Module 2C Input and Output Chapter 2

Inside the System Unit Talking about Computer Hardware The System Unit: Looking Under the hood How Modern Computers Represent data The CPU: The Computer’s “Brain” Microprocessors: Computers on a Chip Comparing CPUs Memory: The CPU’s Electronic Scratchpad Buses: Freeways for Data Module A

Talking about Computer Hardware Inside the System Unit Talking about Computer Hardware Module A Computer and peripherals

The System Unit: Looking Under the Hood The system unit, exposed A Inside the System Unit The System Unit: Looking Under the Hood Module A The system unit, exposed

How Modern Computers Represent Data Inside the System Unit How Modern Computers Represent Data Digital versus Analog Representation digital: high and low power signals analog: continuous variable scale Numbering systems every numbering system has a base Module A

Inside the System Unit Binary Numbers Module A A binary number is called a binary digit, or bit. A bit is the smallest unit of information that a computer can work with.

Inside the System Unit Counting Module A

ASCII & EBCDIC Originally used a total of 7 bits Inside the System Unit ASCII & EBCDIC Originally used a total of 7 bits encodes a total of 128 characters included letters, numbers & punctuation Looking for a wider market IBM and Apple expanded to 8 bits extended character sets not standardized Macintosh and PC versions differ Module A

Representing Data Unicode Parity Representing numbers Inside the System Unit Representing Data Unicode expanded to 16 bits (65,000 characters) can represent most languages Parity extra bit added to coding systems used to ensure code stored correctly odd and even parity Representing numbers floating point notation Module A

The CPU: Looking Under the Hood System Clock Instruction set Inside the System Unit The CPU: Looking Under the Hood System Clock determines speed of the system Instruction set list of instructions Four-step process (machine/processing cycle) Arithmetic-Logic Unit (ALU) arithmetic & logical operations registers are temporary storage Module A

Microprocessors: Computers on a Chip Inside the System Unit Microprocessors: Computers on a Chip Module A CPUs in most computers designed for individuals are microprocessors, which are complete CPUs (control unit and ALU) fabricated on a single chip of silicon.

CPU Compatibility Compatibility Downwardly Compatible CPU Sockets Inside the System Unit CPU Compatibility Compatibility a program that can run on a computer Downwardly Compatible run programs designed for earlier chips CPU Sockets physically holds chip on motherboard established electrical connections upgrade socks allow upgrading processors Module A

Comparing CPUs Data Bus Width & Word Size Inside the System Unit Comparing CPUs Data Bus Width & Word Size number of bits in bus determines word size 16-bit CPU works with 16 bit word size CISC (complex instruction set computer) many instructions & special-purpose circuits RISC (reduced instruction set computer) bare-bones instruction set less expensive, more efficient Module A

Comparing CPUs Multitasking Pentium MMX Benchmarks Pentium MMX Inside the System Unit Comparing CPUs Multitasking processor runs more than one program Pentium MMX contains 57 sets of multimedia instructions more quickly run games & multimedia Benchmarks provides basis of comparison Module A Pentium MMX

CPU’s Electronic Scratchpad Inside the System Unit Memory: CPU’s Electronic Scratchpad Memory Capacities kilobyte (K or KB), megabyte (M or MB), gigabyte (G or GB) Random-Access Memory (RAM) store programs & data being used each memory location has an address volatile Cache Memory allows maximum speed Module A

Inside the System Unit Random Access Memory Module A data In RAM, each memory location has an address, just like a post office box.

Memory Read-Only Memory (ROM) CMOS non-volatile ROM BIOS, flash BIOS Inside the System Unit Memory Read-Only Memory (ROM) non-volatile ROM BIOS, flash BIOS CMOS used to store startup configuration options each memory location has an address volatile Module A

Buses: Freeways for Data Inside the System Unit Buses: Freeways for Data Circuits that carry data from one component to another are called busses. The wider the bus, the more quickly the data can flow Module A

Inside the System Unit Plug and Play Module A Microsoft and Intel created the Plug and Play (PnP) standard. This standard requires special chips on the motherboard, compatible hardware that is expressly compatible with the Plug and Play standard, and a system BIOS that supports Plug and Play.

Data Storage Storage Concepts: The Basics Disks and Disk Drives: Putting a Spin on it Magnetic Tape: Still Useful Optical Storage Media: Seeing the Light Storing Data in Files File Systems in Business: Minding the Store Module B

Storage Concepts: The Basics Memory versus Storage B Data Storage Module B Memory versus Storage

Storage Devices Sequential Random Access Data Storage Sequential go through fixed sequence to get data example: tape backup unit Random Access can go directly to requested data faster, more expensive example: disk drive Module B

Before a disk can be used for storage, it must be formatted Disks & Disk Drives: Putting a Spin on it Data Storage sectors Before a disk can be used for storage, it must be formatted Module B cluster tracks

Floppy Disks A 3 1/2 inch disk B Data Storage write protection tab plastic casing liner disk Module sector hole B spindle hole read/write opening sliding metal shutter A 3 1/2 inch disk