Introduction to Computers Rabie A. Ramadan, PhD

2 Class Information Website ses/2012/intro/

Computing Evolution We Have Come a Long Way!!

The Electronic Numerical Integrator and Computer (ENIAC)  begins in 1938

Home computer as imagined more than 50 years ago

The Computer Evolution Mainframe Computer, 1960 The PC, 1980 Mobile Computer 1990 Sensor Platforms 2000 Smart Dust … Mini-Computer, 1970

Moore’s Law 1965 prediction by Intel cofounder Gordon Moore: The number of transistors that can be built on the same size piece of silicon will double every 18 months

year log (people per computer) Streaming Data to/from the Physical World Excerpted from ‘The Mote Revolution: Low Power Wireless Sensor Network’, UCB, Bell’s Law: New computing class every 10 years

Ubiquitous Computing: A Vision Ahead of its Time The most profound technologies are those that disappear. They weave themselves into the fabric of everyday life until they are indistinguishable from it. Mark Weiser, 1991

Why Computers?

CRT Display Keyboard Mouse “The Box” CD-ROM Drive Floppy Disk Drive

Inside “The Box”

Motherboard

CPU (Central Processing Unit)

SIMM (Single Inline Memory Module)

HDD (Hard Disk Drive)

Power Supply

Schematic Diagram of a Personal Computer...

Ports CPU RAM Disk controller Graphics card Sound card Network card Printer Mouse Keyboard Modem Monitor Speakers bus Computer

“Other” Computing

BIOS CHIP A BIOS chip (Basic Input Output System) is a very important computer component. In simple terms, the BIOS chip wakes up the computer when you turn it on and reminds it what parts it has and what they do!

31 Memory -- "How the processor stores and uses immediate data“ RAM - Random Access Memory The main 'working' memory used by the computer. When the operating system loads from disk when you first switch on the computer, it is copied into RAM. Microsoft Windows volatile As a rough rule, a Microsoft Windows based computer will operate faster if you install more RAM. Data and programs stored in RAM are volatile (i.e. the information is lost when you switch off the computer).

32 Memory ROM – Read Only Memory Read Only Memory (ROM) as the name suggests is a special type of memory chip that holds software that can be read but not written to. A good example is the ROM-BIOS chip, which contains read only software. cards and video cards Often network cards and video cards also contain ROM chips.

33 How Computer Memory Is Measured?

Bytes, Kilobytes, Megabytes and Gigabytes Byte 8 Bits=1 byte KB Kilobyte=1,000 bytes MB Megabyte=1,000,000 (1 million) bytes GB Gigabyte=1,000,000,000 (1 billion) bytes

35 Number Systems

The on and off states of the capacitors in RAM can be thought of as the values 1 and 0, respectively. binary (base 2) number system. Therefore, thinking about how information is stored in RAM requires knowledge of the binary (base 2) number system. decimal (base 10) number system Let’s review the decimal (base 10) number system first. 36

The Decimal Number System 37 The decimal number system is a positional number system. Example: X 10 0 = X 10 1 = 20 6 X 10 2 = X 10 3 = 5000

The Decimal Number System (con’t) 38 The decimal number system is also known as base 10. The values of the positions are calculated by taking 10 to some power. Why is the base 10 for decimal numbers? o Because we use 10 digits, the digits 0 through 9.

The Binary Number System 39 The binary number system is also known as base 2. The values of the positions are calculated by taking 2 to some power. Why is the base 2 for binary numbers? o Because we use 2 digits, the digits 0 and 1.

The Binary Number System (con’t) 40 The binary number system is also a positional numbering system. Instead of using ten digits, 0 - 9, the binary system uses only two digits, 0 and 1. Example of a binary number and the values of the positions:

Converting from Binary to Decimal X 2 0 = X 2 1 = 0 1 X 2 2 = = = 16 1 X 2 3 = = = 32 0 X 2 4 = = = 64 0 X 2 5 = = 81 X 2 6 =

Converting from Binary to Decimal (con’t) Practice conversions: Binary Decimal

Converting From Decimal to Binary (con’t) 43 Make a list of the binary place values up to the number being converted. Perform successive divisions by 2, placing the remainder of 0 or 1 in each of the positions from right to left. Continue until the quotient is zero. Example:

Decimal ‒ to ‒ Binary Conversion The Process : Successive Division a) Divide the Decimal Number by 2; the remainder is the LSB of Binary Number. b) If the quotation is zero, the conversion is complete; else repeat step (a) using the quotation as the Decimal Number. The new remainder is the next most significant bit of the Binary Number. Example: Convert the decimal number 6 10 into its binary equivalent.  6 10 =

Dec → Binary : Example #1 Example: Convert the decimal number into its binary equivalent. 45

Dec → Binary : Example #1 Example: Convert the decimal number into its binary equivalent. Solution:  =

Dec → Binary : Example #2 Example: Convert the decimal number into its binary equivalent. 47

Dec → Binary : Example #2 Example: Convert the decimal number into its binary equivalent. Solution:  =

Dec → Binary : More Examples a)13 10 = ? b)22 10 = ? c)43 10 = ? d) = ? 49

Converting From Decimal to Binary (con’t) Practice conversions: Decimal Binary

Working with Large Numbers = ? Humans can’t work well with binary numbers; there are too many digits to deal with. Memory addresses and other data can be quite large. Therefore, we sometimes use the hexadecimal number system.

The Hexadecimal Number System The hexadecimal number system is also known as base 16. The values of the positions are calculated by taking 16 to some power. Why is the base 16 for hexadecimal numbers ? Because we use 16 symbols, the digits 0 to 9 and the letters A through F. 52

The Hexadecimal Number System (con’t) Binary Decimal Hexadecimal A B C D E F

The Hexadecimal Number System (con’t) Example of a hexadecimal number and the values of the positions: 3 C 8 B

Example of Equivalent Numbers 55 Binary: Decimal: Hexadecimal: 50A7 16 Notice how the number of digits gets smaller as the base increases.

Significant Digits Binary: Most significant digit Least significant digit Hexadecimal: 1D63A7A Most significant digit Least significant digit

Your turn Convert the following number to Hex ? = 2 5 A F. B E 16

Dec → Binary : More Examples a)13 10 = ? b)22 10 = ? c)43 10 = ? d) = ?

Binary Addition 4 Possible Binary Addition Combinations: (1) 0(2) (3) 1(4) Sum Carry Note that leading zeroes are frequently dropped.

Memory Organization

Types of Memory Cache Memory Serves as a buffer for frequently accessed data Small  High Cost RAM (Main Memory) Stores programs and data that the computer needs when executing a program Dynamic RAM (DRAM) Uses Tiny Capacitors Needs to be recharged every few milliseconds to keep the stored data Static RAM (SRAM) Holds its data as long as the power is on D Flip Flop

Types of Memory (Cont.) ROM Stores critical information necessary to operate the system. Hardwired  can not be programmed Programmable Read Only Memory (PROM) Can be programmed once using appropriate equipment Erasable PROM (EPROM) Can be programmed with special tool It has to be totally erased to be reprogrammed Electrical Erasable PROM (EEPROM) No special tools required Can erase a portion

Memory Hierarchy The idea Hide the slower memory behind the fast memory Cost and performance play major roles in selecting the memory.

Hit Vs. Miss Hit The requested data resides in a given level of memory. Miss The requested data is not found in the given level of memory Hit rate The percentage of memory accesses found in a given level of memory. Miss rate The percentage of memory accesses not found in a given level of memory.

Hit Vs. Miss (Cont.) Hit time The time required to access the requested information in a given level of memory. Miss penalty The time required to process a miss, Replacing a block in an upper level of memory, The additional time to deliver the requested data to the processor.

Miss Scenario The processor sends a request to the cache for location X if found  cache hit If not  try next level When the location is found  load the whole block into the cache Hoping that the processor will access one of the neighbor locations next. One miss may lead to multiple hits  Locality Can we compute the average access time based on this memory Hierarchy?

Average Access Time Assume a memory hierarchy with three levels (L1, L2, and L3) What is the memory average access time? h1  hit at L1 (1-h1)  miss at L1 t1  L1 access time h2  hit at L2 (1-h2)  miss at L2 t2  L2 access time h3  hit at L3=100% (1-h3)  miss at L3 t3  L3 access time

Your Assignment 1.Convert the following numbers to binary : Convert the following binary numbers to Hex :

Your Assignment 3. Write a short essay about the importance of computers in social activities ? 69

70 Thank you