1. CS1104: Computer Organisation http://www.comp.nus.edu.sg/~cs1104 Lecture 1: Introduction http://www.comp.nus.edu.sg/~cs1104

2. CS1104-1Lecture 1: Introduction2  Overview Overview  History of Computers History of Computers  Application Areas Application Areas  Types of Computers Types of Computers  Computer Configurations Computer Configurations  Computers as Information Processors Computers as Information Processors

3. CS1104-1Lecture 1: Introduction3  Basic Machine Hardware Architecture Basic Machine Hardware Architecture  CPUCPU  Memory/StorageMemory/Storage  Main MemoryMain Memory  Input/Output DevicesInput/Output Devices  Basic Machine Software Basic Machine Software  FlowchartsFlowcharts  LanguagesLanguages  Operating SystemsOperating Systems  System UtilitiesSystem Utilities  ApplicationsApplications  What’s in CS1104 What’s in CS1104

4. CS1104-1Lecture 1: Introduction4 Overview of Part 1 (1/2)  Number system: how is information represented in a computer.  Boolean Algebra: the basis for logic design and manipulation of information.  Logic gates: what are the gates used, and how circuits can be made from gates.  Function simplification: to reduce the size of design, increase speed, etc.

5. CS1104-1Lecture 1: Introduction5 Overview of Part 1 (2/2)  Combinational circuits: simple circuit design without memory.  Sequential circuits: circuit design with memory.  Disk: storage techniques.  Bus: internal communication.  I/O: devices, technology, etc.

6. CS1104-1Lecture 1: Introduction6 History of Computers (1/4)  Abacus invented in Babylonia in 3000BC  Adding machine by Blaise Pascal (1642) Adding machine  Difference engine and the analytical engine by Charles Babbage (1842) Difference engine and the analytical engine  IBM first electromechanical computer (using relays) designed by Howard Aiken (1937) was based on punched cards.  used to calculate tables of mathematical functions

7. CS1104-1Lecture 1: Introduction7 History of Computers (2/4)  1 st Generation Computers (1940s to early 1950s) – based on vacuum tubes technology. 1 st Generation Computers  1943 – ENIAC: first fully electronic computer, designed by John Mauchly  1944 – Mark I: Howard Aiken  1946 – EDVAC: first stored program computers, designed by John von Neumann  2 nd Generation Computers (late 50s to early 60s) – based on transistors technology. 2 nd Generation Computers  more reliable, less expensive, low heat dissipation  IBM 7000 series, DEC PDP-1

8. CS1104-1Lecture 1: Introduction8 History of Computers (3/4)  3 rd Generation Computers (late 60s to early 80s) – integrated circuits (IC). 3 rd Generation Computers  IBM 360 series, DEC PDP-8  IC – many transistors packed into single container  low prices, high packing density  4 th Generation Computers (present day) LSI/VLSI 4 th Generation Computers  small size, low-cost, large memory, ultra-fast PCs to supercomputers  5 th Generation Computers (future)  massively parallel, large knowledge bases, intelligent  Japan, Europe and US advanced research programs

9. CS1104-1Lecture 1: Introduction9 History of Computers (4/4)  Websites  ACM Timeline of Computing History (http://www.computer.org/computer/timeline) ACM Timeline of Computing History  The Virtual Museum of Computing (http://www.comlab.ox.ac.uk/archive/other/mus eums/computing.html) The Virtual Museum of Computing  IEEE Annals of the History of Computing (http://www.computer.org/annals/) IEEE Annals of the History of Computing  and others (surf the web)

10. CS1104-1Lecture 1: Introduction10 Application Areas (1/2)  Scientific: weather forecasting, simulation, space- program.  one of the earliest application areas.  heavy computation but small amount of data.  Commercial: accounting, banking, inventory, sales.  changes nature of business – information is money.  high data throughput, simple calculations.  Manufacturing: numerical control, CAD/CAM, integration.  graphics, interfacing, device-drivers, networks.

11. CS1104-1Lecture 1: Introduction11 Application Areas (2/2)  Real-time & Control System: air-traffic control, aircraft,nuclear power station.  real time, very fast, safety-critical.  Educational & Recreational  CAI software, multi-media, games, Internet, World Wide Web.  Telecommunication  Network, StarHub CableTV, Singapore One.

12. CS1104-1Lecture 1: Introduction12 Types of Computers (1/2)  Supercomputers:  very fast (Gflops) but expensive machine($10m), vector or parallel processors, used in scientific applications and simulations.  Mainframes:  fast (>10mips) but expensive ($1m), high-throughput, used in large commercial organisations, support many concurrent users interactively.  Mini-computers:  fast but affordable ($200k), used in medium-sized organisations (e.g. SoC), support multiple users.

13. CS1104-1Lecture 1: Introduction13 Types of Computers (2/2)  Workstations:  affordable ($20k) and fast single-user systems (20 riscs mips), good graphics capabilities, engineering, network-based computing.  Micro/Personal/Home Computers:  cheap and affordable ($3k), transportable, home use, good for games and as educational tool, word processing, suitable for small enterprise.

14. CS1104-1Lecture 1: Introduction14 Computer Configurations (1/3)  Stand-alone computer system  Modem connection

15. CS1104-1Lecture 1: Introduction15 Computer Configurations (2/3)  Terminals-host connections

16. CS1104-1Lecture 1: Introduction16 Computer Configurations (3/3)  Network of computers

17. CS1104-1Lecture 1: Introduction17 Computers as Information Processors (1/3) Example: An automobile augments our power of locomotion. A computer is a device capable of solving problems according to designed program. It simply augments our power of storage and speed of calculation. Driver Programmer

18. CS1104-1Lecture 1: Introduction18 Computers as Information Processors (2/3)  Unlike previous inventions, computers are special because they are general-purpose.  Could be used to perform a variety of tasks.  Computer = Hardware + Software.  Hardware: physical components for computation/processing; should be simple, fast, reliable.  Software: set of instructions to perform tasks to specifications; should be flexible, user-friendly, sophisticated.

19. CS1104-1Lecture 1: Introduction19 Computers as Information Processors (3/3) Computer are Information Processors Data Units: 1 bit (binary digit): one of two values (0 or 1) 1 byte: 8-bits 1 word: 1, 2, or 4 bytes, or more (depends on ALU) Computer system Raw data Processed information

20. CS1104-1Lecture 1: Introduction20 Basic Machine Hardware Architecture (1/3)  Main Components:  CPU (Central Processing Unit: controls devices and processes data).  Memory: stores programs and intermediate data.  Input Devices: accept data from outside world.  Output Devices: presents data to the outside world.  An analogy with Human Information Processors:  CPU – brain’s reasoning powers  Memory – brain’s memory  Input Devices – eyes, ears, sensory sub-system  Output Devices – mouth, hands, facial and body expressions

21. CS1104-1Lecture 1: Introduction21 Basic Machine Hardware Architecture (2/3) Monitor (Output) Mouse and Keyboard (Input) Headphone (Output) Hardware box (contains processor, memory, buses etc.)

22. CS1104-1Lecture 1: Introduction22 Basic Machine Hardware Architecture (3/3) Motherboard (Printed Circuit Board) Processor Slots for RAM chips Network card and CRT card Cage for mounting drives Floppy disk drive and Hard disk drive © above picture: Patterson and Hennessy

23. CS1104-1Lecture 1: Introduction23 Hardware – CPU (1/3)  CPU = control unit + ALU + registers  Control Unit : monitors and directs sequences of instructions  Execution Cycle (repeated):  fetch (next instruction)  decode  execute

24. CS1104-1Lecture 1: Introduction24 Hardware – CPU (2/3)  ALU: performs simple arithmetic and logical operations.  Examples: Add, subtract, and, or, invert, increment etc. AB ALU select R = A op B n-bits operations R

25. CS1104-1Lecture 1: Introduction25 Hardware – CPU (3/3)  Registers: temporary results + status information  ACC (accumulator) – current data  PC (program counter) – points to next instruction  IR (instruction register) – current instruction  MA (memory address) – address to read/write  MB (memory buffer) – data to read/write

26. CS1104-1Lecture 1: Introduction26 Hardware – Memory/Storage (1/2)  Purpose: to store program and data.  Desirable Traits: fast access, large capacity, economical, non-volatile.  However, most memory devices do not have all these traits.

27. CS1104-1Lecture 1: Introduction27 Hardware – Memory/Storage (2/2)  Solution: hierarchical combination registers main memory disk storage magnetic tapes Fast, expensive (small numbers), volatile Slow, cheap (large numbers), non-volatile

28. CS1104-1Lecture 1: Introduction28 Hardware – Main Memory (1/2)  Fast BUT volatile (need power to maintain data)  Logical structure – table of memory cells/units. 01230123 2 m -3 2 m -2 2 m -1 addresses memory cells 8 bits or more MARMAR MBRMBR address data

29. CS1104-1Lecture 1: Introduction29 Hardware – Main Memory (2/2)  Memory cells may be grouped into pages (say 512 consecutive words per page).  Units  1 KBytes = 1024 (or 2 10 ) bytes  1 MBytes = 1024 Kbytes (or 2 20 bytes)  1 GBytes = 1024 Mbytes (or 2 30 bytes)

30. CS1104-1Lecture 1: Introduction30 Hardware – Input/Output Devices  Input devices: read/accept data (into computer)  obsolete: card reader, paper tape reader  present: keyboard, mouse, light-pen, optical char reader  future: voice and vision recognition.  Output devices: write/display data (to users)  obsolete: card & paper punch, teletype  present: VDU (visual display unit), printers, plotters, graphics display, sound  future: voice synthesis.

31. CS1104-1Lecture 1: Introduction31 Basic Machine Software (1/2)  Software is the key to making computers general purpose.  Software are often built hierarchically, with layers of software providing successive higher-level of abstractions.  This structure is reflected by the following onion layer view of software.

32. CS1104-1Lecture 1: Introduction32 Basic Machine Software (2/2) Hardware Operating system System utilities Applications/User programs

33. CS1104-1Lecture 1: Introduction33 Software – Flowcharts (1/2)  The sequence of instructions of a software/program can be graphically specified using flowcharts.  The flowchart technique maybe a little outdated but could still be used in a clear manner for simple problems.  As an example, the procedure to find the roots of a quadratic equation, ax 2 + bx + c = 0, can be written using the following equation:

34. CS1104-1Lecture 1: Introduction34 Software – Flowcharts (2/2)  This procedure can be coded in the following flowchart: Read a,b,c a=0? d:=b 2 - 4ac d>0 d=0 d<0 Write real root Write complex roots Write real roots =< > no yes Write not quadratic

35. CS1104-1Lecture 1: Introduction35 Software – Languages (1/4)  All programs will have to be coded in some programming language – usually text-based.  The native language of machine is called machine language.  This consists of a set of primitive instructions, coded in numbers.  An example is “0310 0412 0512”. But can you understand what it does?

36. CS1104-1Lecture 1: Introduction36 Software – Languages (2/4)  Possible to use more human-readable mnemonic instructions.  These are know as assembly language instructions.  Normally, assembly language has a 1-to-1 correspondence with machine language.

37. CS1104-1Lecture 1: Introduction37 Software – Languages (3/4)  Assembly language is still very primitive.  Higher-level Languages, like Pascal, C, Fortran, which are a little closer to English language have been developed.

38. CS1104-1Lecture 1: Introduction38 Software – Languages (4/4)  An example Pascal program to find roots of quadratic equation: read(a,b,c); if a=0 then writeln ("not a quadratic equation") else begin d := sqr(b)-4*a*c; if d>0 then writeln ("complex roots") else if d=0 then writeln("single root =",-b/(2*a)) else writeln ("root1=",-b+sqrt(d)/(2*a), "root2=", -b-sqrt(d)/(2*a)); end;

39. CS1104-1Lecture 1: Introduction39 Software – Operating Systems (1/2)  Operating System (OS) is situated directly above hardware. It controls and manages the available hardware resources.  Often, OS has special access privileges to certain categories of instructions and certain hardware  User programs have to go through OS for these privileges.

40. CS1104-1Lecture 1: Introduction40 Software – Operating Systems (2/2)  Associated Functions/Tasks:  boots up machine  loads user program  allocates main memory/storage space  schedules concurrent user programs  drivers to service various devices (terminals, printers, etc.)

41. CS1104-1Lecture 1: Introduction41 Software – System Utilities (1/2)  Above the OS, there is a set of frequently executed programs,called System Utilities. These utilities are often packaged with OS.  Used by programmers/analyst to help develop applications.  Some examples  Editor: compose/edit user programs or data files  Assembler: translates assembly to machine code  Compiler: translates high-level language to assembler/machine code  Spooler: temporary stores print files for queuing

42. CS1104-1Lecture 1: Introduction42 Software – System Utilities (2/2)  Some examples (continued)  Mailer: forwards/receives mails between users  DBMS (Data-Base Management System): centralised management of data at a more abstract level than files  Window Management System: multiple windows can appear on single screen. These together with various graphical entities (e.g. menus,panels, buttons) can be managed by WMS.

43. CS1104-1Lecture 1: Introduction43 Software – Applications  Word-Processors: compose/edit reports/articles  Accounting Package: keeps track of accounting transactions, produces daily/weekly/monthly (profit/loss) reports  Inventory System: keeps track of stock levels  Personnel/Payroll System: staff records, monthly salary

44. CS1104-1Lecture 1: Introduction44 What’s in CS1104 I/O systemProcessor Compiler Operating System (Windows XP) Instruction Set Architecture Datapath & Control Memory Software Assembler Computer Architecture Application (Netscape) Digital Design transistors Hardware Digital Logic Design

45. CS1104-1Lecture 1: Introduction45 End of file