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Machine Architecture

Machine Architecture. An Introduction to Computer Components. Machine Architecture and Number Systems. Topics Major Computer Components Bits, Bytes, and Words Reading Sections 1.1 - 1.3 Appendix E (Sections E.1, E.4, E.5). Major Computer Components. Central Processing Unit (CPU) Bus

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Machine Architecture

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  1. Machine Architecture An Introduction to Computer Components

  2. Machine Architecture and Number Systems Topics • Major Computer Components • Bits, Bytes, and Words Reading • Sections 1.1 - 1.3 • Appendix E (Sections E.1, E.4, E.5)

  3. Major Computer Components • Central Processing Unit (CPU) • Bus • Main Memory (RAM) • Secondary Storage • I / O Devices • Starting the computer

  4. CPU • Central Processing Unit • The “brain” of the computer • Controls all other computer functions • In PCs (personal computers) also called the microprocessor or simply processor.

  5. The Bus • The computer is made up of different components, like the CPU and main memory (see diagram) • The components are connected by the bus • A bus is a group of parallel wires that carry control signals and data between components

  6. Main Memory • Main memory holds information such as computer programs, numeric data, or documents created by a word processor. • Main memory is made up of capacitors. • If the capacitor is charged, then its state is said to be 1 or ON. • We could also say the the bit is set. • If the capacitor does not have a charge, then its state is 0 or OFF. • We could also say that the bit is reset or cleared.

  7. Size of Capacitors • Has decreased dramatically over the last 20 years. • Now we can fit several million capacitors on a chip the size of a dime. • As this technology becomes older, we can expect the price of memory to decrease. Is it already decreasing ? ABSOLUTELY !

  8. Main Memory (con’t) • Memory is divided into cells, where each cell contains 8 bits (a 1 or a 0). Eight bits is called a byte. • Each of these cells is uniquely numbered. • The number associated with a cell is known as its address. • Main memory is volatile storage. That is, if power is lost, the information in main memory is lost.

  9. Main Memory (con’t) • Other computer components can: • get the information held at a particular address in memory, known as a READ, • or store information at a particular address in memory, known as a WRITE. • Writing to a memory location alters its contents. • Reading from a memory location does not alter its contents.

  10. Main Memory (con’t) • All addresses in memory can be accessed in the same amount of time. • We do not have to start at address 0 and read everything until we get to the address we really want (sequential access). • We can go directly to the address we want and access the data (direct or random access). • That is why we call main memory RAM (Random Access Memory).

  11. Secondary Storage Media • Disks -- floppy, hard, removable (random access) • Tapes (sequential access) • CDs (random access) • DVDs (random access) • Secondary storage media store files that contain • computer programs • data • other types of information • This type of storage is called persistent (permanent) storage because it is non-volatile.

  12. I/O (Input/Output) Devices • Information input and output is handled by I/O (input/output) devices. • More generally, these devices are known as peripheral devices. • Examples: • monitor • keyboard • mouse • disk drive (floppy, hard, removable) • CD or DVD drive • printer • scanner

  13. Media • Many I/O devices work in conjunction with media • A medium holds information (programs, data, text files) • Examples: • floppy disk (not the drive itself) • hard disk (not the drive itself) • magnetic tape (not the drive itself)

  14. Bits, Bytes and Words • A bit is a single binary digit (a 1 or 0). • A byte is 8 bits • A word is 32 bits or 4 bytes • Long word = 8 bytes = 64 bits • Quad word = 16 bytes = 128 bits • Programming languages use these standard number of bits when organizing data storage and access.

  15. Booting the Computer • The term boot comes from the expression pulling yourself up by your bootstraps. • It refers to the computer’s start-up procedure. • When the computer is first turned on, it reads start-up instructions found in the ROM chips.

  16. Booting the Computer (continued) • These instructions cause the computer to do a series of tests. Each of the components is tested. • The last thing that happens during boot is that the operating system is loaded from the hard disk into RAM. • The computer cannot do anything until the operating system is loaded, because the operating system manages all of the basic functions of the computer.

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