A n n o u n c e m e n t s Computer Science 1A Introduction to Computer Science Hardware H A R D W A R E Refers to the physical components of the computer Input Output devices Secondary storage Memory CPU Buses Chapter 1 Hardware S t o I r a O g e N o n D e v i c e s Lab 2 Due Next week Quiz 2 Simple Computer Next week Check the calendar for due dates Keyboard Monitor Printer Mouse Microphone speakers Etc 4 of 24 Inside your Computer Secondary Storage I n s i B d o e x Memory RAM Ports Buses to Input Ouput I O Devices Chapter 1 Hardware 2 of 24 I O D e S v t i o c r e a s g e 1 of 24 Chapter 1 Hardware t h e Allow the computer to communicate with the outside world Do not store data Chapter 1 Hardware Buses Central Processing Unit 3 of 24 AKA auxiliary storage devices Cheaper than memory Non volatile Examples Magnetic disk typical hard disk drive Platters Constructed of light aluminum alloy OR glass or ceramic more resistant to heat Coated with magnetizable material ferrite compound On both sides Can have several platters In 2008 typically store in the high GBs and TBs Chapter 1 Hardware 5 of 24 1 M o r e S t E o x r t a e g r e n a l M a i n M e m o r y Special type of Electronically Erasable Programmable Read Only Memory Non volatile Chip 3 t y p e s Compact Discs CDs Digital Versatile Discs DVDs Blu ray Discs BDs ROM Read only R WORM Write Once Read Many R W Read Write more expensive How much do they typically hold CD 650 MB DVD 4 7 GB BD 25 GB DVDs and BDs can be dual layer 2 record on both sides USB flash drives flash drives USB drives jump drives pen drives thumb drives key drives tokens Flash RAM or Flash Memory Can R W w M e e m m o e r a y s u r e Remember bytes More useful for storing information than 1 bit Used to represent a character in ASCII American Standard Code for Information Interchange Used to be 128 chars extended is 256 chars Word the of bits an instruction can have machine specific 16 32 or 64 bits Chapter 1 Hardware T y p e s ROM M e m o r y Contents written my computer manufacturer Read only can t write to it Bootstrap is on the ROM chip Non volatile 8 of Chapter 1 Hardware 24 Unit Faster than RAM slower than CPU registers Between registers and primary memory Cheaper and more plentiful than registers Relatively small amount of memory Compared to RAM Contains a copy of a portion of main memory CPU checks to see if requested portion is in cache If so it retrieves it If not it has to go to main replaces cache with new data retrieved Most processing is performed with a small portion of data so mostly will be in cache Chapter 1 Hardware We measure memory external storage in terms of bytes Number of Bytes Decimal Approximation kilobyte 210 103 megabyte 220 106 gigabyte 230 109 terabyte 240 1012 petabyte 250 1015 exabyte 260 1018 zetta 270 1021 Yotta 280 1024 B U S E S 10 of 24 9 of 24 Electrical pathways wires Each wire can transmit 1 bit of information These connect all the components to the CPU System Bus Internal Bus CPU and Memory Chapter 1 Hardware 7 of 24 Cache o f 2 Read Only Memory Like a street address but always unique The address is in binary 1s and 0s H o w Each has its own address o f RAM Read Write ALL programs and data must be in RAM to be processed Volatile Most of main memory Collection of storage locations Not the same as a hard drive this is internal to the system located on the mother board MUCH faster 6 of 24 Random Access Memory M e m o r y Expansion Bus External Bus CPU and I O Devices Chapter 1 Hardware 11 of 24 2 S y s t e m The CPU transfers data addresses to main Memory Von Neumann s paper proposed a single bus but this created a bottleneck so 3 types of Buses Data Bus moves data between main memory and the CPU registers Address Bus holds the address of the data that the data bus is accessing Control Bus carries the instructions that specify how the information transfer is to take place B U S E S Data Bus moves data from the main memory to the CPU and back of wires is dependent on the computer s word size I N T E R N A L B U S E S 16 bit 16 wires 32 bit 32 wires etc 1 word is transmitted at a time Address Bus holds the address of the data that the data bus is currently accessing Used to access a specific word in memory of wires is dependent upon address space of addressable locations Control Bus Indicates whether or not a read or write is to be performed 12 of 24 13 of 24 Chapter 1 Hardware E x p a B n u s s i o n I O devices communicate with the CPU Memory through ports T h e These ports are connected to an Expansion or PCI bus w C i P t U h The Expansion or PCI bus communicates with the System Bus through a bridge The bridge manages traffic between the Expansion bus and the System bus The system bus is much faster than the Expansion or PCI bus 14 of 24 i n t e r a c t s SYSTEM BUS M e m o r y Built the ENIAC UNIVAC while building the ENIAC M a u c h l y T H E C P U John Von Neumann published the idea of storing programs and data internally We call this the Von Neumann architecture Chapter 1 Hardware Central Processing Unit The brain of the computer Divided into 3 parts Registers CU ALU CPU Registers PC Program Counter R1 R2 R3 IR 16 of 24 Chapter 1 Hardware Control Unit CU Data E c k e r t Came up with a way to store programs To create a new program on the ENIAC wires had to be unplugged and plugged into new sockets 15 of 24 Chapter 1 Hardware Arithmetic Logic Unit ALU 17 of 24 3 E l e m e n t s Control Unit CU t h e Transfers data to and from memory Calls the Arithmetic Logic Unit when necessary Fetches instructions Interprets instructions Executes instructions in order R e g i s t e r s Arithmetic Logic Unit ALU Performs all arithmetic logical operations Arithmetic operations Increment Decrement unary operations 1 input operand Addition Subtraction binary …