COMPUTER ORGANIZATION & ARCHITECTURE EIE 411 Course Lecturer: Engr Banji Adedayo. Reg COREN. The characteristics of different computers vary considerably from category to category. Computers for data processing activities have different features than those with scientific features. Even computers configured within the same application area have variations in design. Computer architecture is the science of integrating those components to achieve a level of functionality and performance. It is logical organization or designs of the hardware that make up the computer system. The internal organization of a digital system is defined by the sequence of micro operations it performs on the data stored in its registers. The internal structure of a MICRO-PROCESSOR is called its architecture and includes the number lay out and functionality of registers, memory cell, decoders, controllers and clocks. HISTORY OF COMPUTER HARDWARE The first use of the word ‘Computer’ was recorded in 1613, referring to a person who carried out calculation or computation. A brief History: Computer as we all know 2day had its beginning with 19th century English Mathematics Professor named Chales Babage. He designed the analytical engine and it was this design that the basic frame work of the computer of today are based on. 1st Generation 1937-1946 The first electronic digital computer was built by Dr John V. Atanasoff & Berry Cliford (ABC). In 1943 an electronic computer named colossus was built for military. 1946 – The first general purpose digital computer- the Electronic Numerical Integrator and computer (ENIAC) was built. This computer weighed 30 tons and had 18,000 vacuum tubes which were used for processing. When this computer was turned on for the first time, lights dim in section of Philadelphia. Computers of this generation could only perform single task, and they had no Operating system. 1 2nd Generation 1947-1962 use transistors instead of vacuum tubes. In 1951 the Universal Automatic Computer (UNIVAC) as the first set of commercial computers were introduced to the public. In 1953- International Business Machine (IBM 650 & 700) made their mark, computer programming languages were developed, computer had memory and OS. Storage media such as tape and disk were in use, also were printers for output. 3rd Generation 1963 to date – The invention of IC, computers became smaller, more powerful, more reliable and able to run many programs at the same time. In 1980 MS-DOS was born In 1981 IMB introduced the Personal Computer (PC) for homes and office. In 1985 Apple gave us the Macintosh computers with its icon driven interface and 90’s gave us Window Operating System. The melelium computers in the year2000 series computers laptops with built-in-video camera, palmtops, flat screen, Apple tablets, hp slate computer, Lenovo hybrid note book and many ‘computer on the go’ such as Blackberry with touch-sensitive screen, ability to recognize voice commands, and dictation of texts, a built-in-video camera. As a result of the various improvements to the development of the computer, we have seen the computer being used in all areas of life be it: telecoms, space technology, marine, education, health, business and as artificial intelligence (Robotics). COMPONENTS OF COMPUTER While structure of computers could be likened to the anatomy and physiology of the computer, like the classification of humans as consisting of body and soul, computer could be subject to like that namely: Computer Hardware: this refers as electronic and mechanical parts. Hardware includes input devices, output devices, system unit, storage unit and communication devices. Input devices- it enables us enter data into computer eg keyboard, mouse, scanner, microphone, digital camera, pc video camera. Output devices- It gives information to the users eg Monitor (VDU), printer, speaker. The system Unit- it contains all the electronic components which is the internal hardware. They are: power supply Unit, mother board, RAM, ROM, CD Drive, hard Disk, the monitor (VDU), keyboard, mouse. Optional Peripherals: stabilizers/surge protectors, UPS. 2 The assembly, maintenance of system unit is handled by system Engineer. Computer Software- Computer will not work without software. Software also call programs are instructions that tell computer what to do and how to do it. Three main Software: 1. System software (Also called OS) eg Unix, MS-DOS, Window NT, Sun OS, etc 2. Application Software- It allows specific task eg word processing, excel, power point, e-mail application, internet application ( Internet explorer, fire force) 3. utility software eg antivirus, Zip, Maintenance software (tele-diagnosis) etc. The prophesy on the death of PC The two words that will kill the dominating world of computing by Bill gate is “CLOUD COMPUTING”. The days of paying for costly software upgrades are numbered. The PC will soon be obsolete. IT consulting firm IDC reports that every dollar a company spends on a Microsoft products results in an additional $8 of IT expenses. The two words CLOUD COMPUTING scare the hell out of Bill Gates. Bill Gate has to say: “the next sea change is upon us”. Thanks to the thousands of miles of fiber-optic cable laid during the late 1990’s and middle of 2000’s in Nigeria, the speed of computer networks has finally caught up to the speed of the computer processors. Suddenly computers that were once incompatible and isolated are now linked in a giant network or “Cloud”. As a result, computing is fast becoming a utility in much the same that electricity did. Think back a few years –any time you wanted to type a letter, create a spread sheet, edit a photo or drawing or play a game, you had to go to the store, and install it on your computer. Presently in Nigeria every computer users in Nigeria will be struggling to hook to the “CLOUD”. GENERAL COMPUTER ARCHITECTURE A typical computer system can be divided into 3 sections namely: (a) Control section: It executes instruction and processes data (b) Memory section: It stores data instructions 3 (c) Input and output section: handles communications between the computer and outside world. Also, these sections are interconnected to one another by tiny wires which constitute the conducting paths called buses. Buses are divided into three: Control bus Data bus Address bus Control Bus: used to send control signals generated in timing and control circuits of microprocessor to the memory and the input and output units (I/O). Control bus is uni- direction. eg It carries read or write signals to memory and i/o parts Data Bus: Used to transfer machine instructions and data from the memory to the microprocessor; and data associated with I/O transfers only. Data bus is bi-directional in nature as distinct from control and address busses (one direction). It consists of tracts that carry 8 bits or 1 byte word simultaneously. Address Bus: used to transfer the address of the location in memory or the I/O part involved in data transfer. N.B: Some of these buses may be physically the same, a single bus may carry data in different directions or addresses at times. As a result, a bus for more than one purpose is shared or multiplexed. Shown below is the block diagram of typical computer system. CONTROL I/O Address data & instruction Data MEMORY I/O Direct Memory Access To & from peripherals Fig 1a 4 CPU BUS CPU MEMORY IEEPROM CLOCK MEMORY RAM Fig 1b LED DISPLAY KEYBOARD OR VDU INPUT Fig1a &b Shows a block diagram for a generic computer system. 5 A computer is a machine that computes, processes and store information. A micro- computer is a computer that has been integrated into a very large scale integrated circuit (VLSIC). There are all sorts of micro-computers, but one important class of micro- computer is Micro-controller. A micro-controller is a micro-computer that has been specially designed to interact in a timely manner with different types of devices in the outside world. The Fig1b shows that a computer consists of a CENTRAL PROCESSING UNIT (CPU), a CLOCK, MEMORY and PERIPHERAL or I/O devices. All of these subsystems communicate over a CPU bus. INPUT/OUTPUT SECTION It handles the transfer of data between the computer and external devices or peripherals. The transfer involves status and control signal as well as data. The input/output must reconcile time difference between the computer and the peripherals, format the data properly, handle status and control signals and supply the required voltage level, irregular transfer may be handled with interrupts control signals that receives immediate attention of the control section and cause the suspension of its activity. A typical I/P operation proceeds as follows: The peripherals signal the control section that new data is available. The I/O section must format the signal properly and hold it until the control accepts it. It sends data to the control section. The I/O section must hold the data until control section is ready to read it. The control section reads the data. The I/O section must have a decoding mechanism that select a particular part of the instruction. After reading the data, the control signal is deactivated and the peripheral is acknowledged for more data to be sent. Output operations are much like input operations. The peripherals indicates to the control sections that it is ready to accept data The control section then sends the data along with a signal ( a strobe) that indicates to the peripheral that the data is available. The I/O section formats the data and control signal properly; and hold the data long enough for the peripheral to use it. 6 O/P data must be held longer than I/P data, since mechanical devices, lighted displays and human observers respond much more slowly than computers.