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Unformatted text preview: Computer Architecture Margot Gerritsen Shela Aboud Emmet Caulfield January 5, 2010 1 Outline Outline Computers represent everything in binary , so well review number systems before we talk about computer architecture. Contents 1 Number Systems and Representations 1 1.1 Bases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Representations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 Machine Architecture 4 There are many different kinds of computer systems from largely invisible em bedded systems in microwave ovens and cars, through devices we dont usually think of as computers per se , but would immediately know are (to a large degree at least), like iPods and cellphones, to the real (generalpurpose) computers like servers, desktops, and notebooks that we think of as computers proper. For our current purpose, we adopt a fairly narrow meaning of computer to mean a computer like a Mac or a PC. But before we can understand the basic architecture of the computer, we have to have a little background information about how computers represent data. As you probably already know, computers store information in ones and zeros in binary . 1 Number Systems and Representations You probably know that computers are essentially devices that manipulate num bers extremely quickly and have heard of computers being 32bit or 64bit, which is the number of bits binary digits in the microprocessors registers (a kind of scratchpad within the microprocessor where a number can be manip ulated). Historically, the first microprocessor (the Intel 4004) was 4bit, later microprocessors were 8bit, 16bit, and 32bit. Modern processors are 32bit or 64bit, but even now 8bit microprocessors are still used in embedded systems like dishwashers and microwave ovens. 1.1 Bases In binary, the weights of positions, rather than being units, tens, hundreds, Number Systems & Computer Architecture Outline Number Systems and Representa tions Bases Representations Machine Architecture Number Systems & Representations Number systems base n , binary, octal, hexadecimal Representation of integer, negative, and fractional numbers Motivate the notion of type Figure 1: Number Systems and Representations thousands, ..., are instead units, twos, fours, eights, sixteens, etc. It should be obvious that any integer that can be represented in one number system can be represented in another. For real numbers, the only difference is that numbers that recur after the decimal point typically dont in other number systems consider 1 3 in bases 10 and 3 (0 . 333 . . . 10 = 0 . 1 3 ). In a computer, the number of values that can be represented in a memory region or a register is dependent on the number of bits in a nybble (4 bits) 16 distinct values can be represented; in a byte (8 bits), 256; in 16 bits (two bytes), 65536, etc....
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This note was uploaded on 06/17/2010 for the course CME 211 taught by Professor Staff during the Winter '10 term at Stanford.
 Winter '10
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