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I202, Session 5, Fall 2003. Thomas Haigh 1

The Personal Computer

I202, Fall 2003Session 5

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Open Architecture

n The crucial theme for this sessionn Trace from Altair and Homebrew Computer

Club to todayn Examine current structure of PC architecture

& its relationship to industry structuren Look at influence of Hacker culture

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Microprocessor is Key

n Makes cheap, small computer possible

n Some early systems very basic

n KIM 1 systemn 256 bytes RAMn Processorn 6 number LEDn Keypad

n Program inmachine code

Intel 4004

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The MITS Altair

n First commercial personal computern Intel 8080 processorn 256 bytes of RAM

n Sold in kit formn 4000 in 3 months

n Initiallyn no softwaren no interfacesn not much use

n Microsoft gets started writing BASIC for it!

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Inside the Altair

n Nationally, Altair tapped into culture of electronics hobbyistsn Like building

burglar alarms, etc.

n First advert in Popular Electronics

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The S-100 Bus

n Computers are basically just racks

n Standard bus connects many cardsn Process cardn Memory cardsn Tape interface cardn Terminal interface cardn Disk controller cardn etc.

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Homebrew Computer Club

n In San Francisco arean Read about it in Hackers chapter

n Begin designing hardware for own usen Boards for Altair, then whole computersn Companies such as Processor Technology, Apple are

formed to manufacture designsn Relies on

n Silicon Valley electronics industry already well established

n Large numbers of engineers and hobbyistsn Existing interest in public access computing

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Other Early Suppliersn Many are clones of Altair

n IMSAI, Compupro, Zenith, etc.

n Other designs are more integratedn Processor, memory, etc. on

one board

n Apple I takes this approachn PET, SOL, Tandy (Radio

Shack) are similar

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CP/M

n Developed by Digital Research, 197Xn Stands for Control Program/Moderator

n First standard operating system for PCsn Licensed to many small PC makersn Thousands of programs developed

n Very basic capabilitiesn Access screen and disk drivesn Copy and organize files

n MS-DOS is basically a copy of

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The Apple II

n First truly mass produced PCn Launched in 1977n Final major revision in 1988,

sold until 1993!n Sleek case holds

n Integrated color graphics, RAM, tape controller

n 7 slots for addonsn Disk controller very popularn Expandability key to success

n Basic (4K RAM) model cost $970

n By 1982, Apple has more than $1billion annual revenues, has sold 750,000 Apple IIs

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Early Purchasers

n Many are home usersn Will discuss next time

n Different motivationsn Existing electronics hobbyistsn Want to see what the fuss is aboutn Have idea to make business more efficientn Like to try gadgets

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Business Use

n Early business applications fairly limitedn Apple II typical configuration has

n No easy access to lower case lettersn 40 columns only on screenn Only 100K or so storage on a disk

n As a result, only enthusiasts would use forn Wordprocessingn Database

n Machines with hard drives, etc. are much more expensive (minicomputers or some CP/M systems)

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Visicalc: The First Spreadsheetn Story is given in the Levy reading

n Launched in 1979 by Dan Bricklin & Bob Frankston

n Works very much like Excel and other modern spreadsheets

n Very well suited to Apple II becausen Needs interactive interface,n but doesn’t need much file space or big screen (screen

scrolls)n First “killer application”

n Single package large number of people will buy a computer just to run

n Makes PC into respectable business machine

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The IBM PC

n Launched in 1981n Very “open” for IBM

n Built from standard hardware

n Has expansion slotsn Solidly constructed & well

pricedn Nothing unique

n Has (partly) 16 bit processor, Intel 8086n Up to 640K of RAM

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MS DOS

n IBM contracts with Microsoft for operating systemn Rapid hack of CP/M-like systemn Legality has been questioned

n Microsoft retains rightsn Licenses to other companiesn Crucial to emergence of PC-compatible

computers

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Expandability

n Basic model not very powerfuln 16KB of RAM, tape interfacen Floppy disks, video card are popular options

n Use expansion slots forn Printer controllern Serial port for modemn “Real Time” clock to remember time, etc.

n Many companies produce cardsn dramatically improve original machinen e.g. “Hercules” graphics board, video on text monitor

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Early PC Clones

n First PC-compatibles run MS-DOSn Don’t always have 100% compatible hardware

n Compatibility achieved whenn IBM ROM chip is “reverse engineered”n rest of hardware can be ordered off the shelf

n Soon, chipsets are createdn integrate many PC chips into a fewn make clones easy and cheap to design

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Clones Take Over Market

n Compaq is biggest early successn Quality machines cheaper than IBM

n Leads market for “portables”

n Hundreds of others follown Small neighborhood PC firmsn Mail order operations like Dell

n IBM becomes a minor player in “IBM PC” marketn victim of its own open architecture

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Graphical User Interfacen Windows, Icons, Mouse,

Pull-down menusn alternative to typed

commands and text menusn Concept developed by

Xeroxn PARC research center leads

world in 1970s. Inventsn Ethernetn Graphical user interface

(but not mouse)n Laser printern Smalltalk graphical,

object-oriented programming

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Apple Macintoshn Launched 1984

n Apple’s second go at graphical user interface

n Lisa launched 1983n First mass market PC with

n Graphical interfacen Mouse

n First versions underpoweredn Sell in small numbersn RAM and disk too smalln Not expandable

n Problems fixed in 1986n Mac Plus is a hit

n Mac II in 1987n colorn expandability (PC-type slots)

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Windowsn Windows is graphical “shell” on top of

DOSn By mid-1980s, GUI is wave of the futuren Several competitors

n Windows 1.0 released in 1985n Late, slow, unpopular

n Windows 3.0 in 1990n Good enough to run programs on

n Version 3.1 becomes mainstream PC OS

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Windows 1.0 in actionMS-DOS Executive, used to display file listings and open programs

Paint. Like write, and notepad this remains in Windows today

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The PC Today

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Gradual Evolution

n While retaining backward compatibility in hardwaren approx 1,000 increase in processor powern approx 2,000 increase in memory size

n as standard hardwaren Networking (wired & wireless)n Powerful color & 3D graphicsn Audio capabilitiesn 3.5 inch floppy, hard drives, CDs, DVDs, etc.

n also turned from desktop platform into servern Multiprocessors (up to 32)n Support for “RAID” drive arrays

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New Software Capabilities

n PC of 2000 has architecture of powerful minicomputer of 1990

n Multitaskingn Running several programs at a timen Protecting system from application crash

n Graphical user interfacen “Plug and play” hardware installation

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A Modern PC Motherboardn DFI “Lan

Party Pro875”

n This one is high-end, and designed for stylen Glows

under blacklight

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Parts of a Modern PCn Motherboard

n Includes Ethernet, drive controller, USB, etc

n Inserted into motherboardn Processor chipn Memory (in SIMM modules)n Graphics card (sometimes integrated)n Sound card (usually integrated)

n Case, into which are screwedn Motherboardn Hard diskn Floppy diskn DVD and CD/RW disks

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No Single Firm Makes PCs

n No major vendor (Dell, HP/Compaq, etc)n Manufactures any significant component

n Processor, motherboard, hard disk, etcn (Partial exception: IBM still makes some

electronics)

n Everything manufactured by specialistsn Mostly in Taiwan, Korea, Chinan Specialize in motherboards, sound cards, etc.

n Not even significant custom designn Maybe a few tweaks to case

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PC Firms Compete On

n Brand Imagen Sales and servicen Customer support

n Efficient logistics and procurementn Pay lessn Keep smaller stocksn Direct sales, built to order is winning strategy

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Competition In Each Niche

n Suppliers of each component competen Motherboard manufacturers

n Cost, reliability, features

n Chipset manufacturersn Reliability, features, integration, cost

n Case manufacturersn Style, weight, ease of assembly, cost

n Graphics card manufacturersn Performance, cost, drivers

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Hardware Hacks Todayn Creative but limitedn Case Mods

n Macs turned into fishtanksn Cases with lights, fans,

bright colorsn Overclocking

n Running processor faster than intendedn e.g. at approx 900 MHz

instead of 850

n Can require heavy cooling systemsn Extreme examples include

liquid refrigeration

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Open Architecture Triumphs

n Economic benefits ofn Economies of scale for overall market

n Specialized producers in each nichen Competition at every level

n No one supplier matters too much

n Historical transitionn Altair & S100 -> Homebrew Club -> Apple II -> IBM

PC -> Today’s computers

n Carry forward idea of open archiecture

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Reality Check

n Not all components interchangeablen Intel dominates processor fieldn Microsoft dominates OS market

n Both control strategic elements of systemn Much bigger profit marginsn Much more control over overall evolution of

PC