1 More on Computer Components Computer switches Binary number system Inside the CPU Cache memory Types of RAM Computer buses Creating faster CPUs NEXT SLIDE

2 Digital Data: Switches and Bits Electronic switches: –Vacuum tubes –Transistors –Integrated circuits Binary number system: –Representing numbers –Representing letters and symbols ASCII Unicode ON OFF NEXT SLIDE

3 Electronic Switches Non-mechanical devices in computers that open and close circuits Types of electronic switches: –Vacuum tubes –Transistors: Semiconductors –Integrated circuits NEXT SLIDE

4 How Transistors Work

5 The on/off state of a switch represents one bit of data Bit (binary digit): –On = 1 –Off = 0 OFF Switches Representing Data ON 01 OR = 1 bit NEXT SLIDE

6 The Binary Number System x x x digits 0 through 9 Base digits 0 through x x x8 8 2x4 4 2x2 2 2x1 1 Number systems: –Organized ways to represent numbers Binary 2 digits 0 and 1 89 Base 10 = NEXT SLIDE

7 NEXT SLIDE Representing Letters and Symbols A ON OFF aBbC American Standard Code for Information Interchange (ASCII): –8 bits equal 1 byte –256 different combinations –1 byte equals an alphanumeric character or symbol Unicode: –16 bits equal 1 byte –65000 different combinations –Used for all languages: English, Japanese, Chinese, etc. Click here to view an ASCII Code chart

8 ASCII Chart

9 The CPU: Processing Digital Information CPU components Types of CPUs What the CPU does: –Machine cycle: System clock Cache memory NEXT SLIDE

10 The CPU Also known as a microprocessor or processor Executes instructions Components include: –Control unit –Arithmetic logic unit (ALU) –Registers –Cache memory NEXT SLIDE

11 Types of CPUs PROCESSORMANUFACTURE R TRANSISTOR S CLOCK SPEED Athlon XPAMD54.3 million2.20 GHz Athlon 64FXAMD106 million2.4 GHz CentrinoIntel77 million1.70 GHz Itanium 2Intel410 million1.50 GHz Pentium 4Intel55 million3.20 GHz Pentium 4 Processor-M Intel55 million2.60 GHz PowerPC G4Motorola57 million1.00 GHz PowerPC G5IBM58 million2.00 GHz NEXT SLIDE

12 The CPU’s Machine Cycle Also known as the processing cycle Fetch: –The Control Unit searches cache memory and then RAM for program instructions –Instructions are moved to the Control Unit Decode: –The Control Unit reads and prepares the program instructions –The instructions are sent to the ALU Execute: –The ALU performs the calculations Store: –The results are stored in the registers Click here to view the video “Inside the Chip” by Intel NEXT SLIDE

13 Inside the Chip

14 The System Clock Located on the motherboard Controls the CPU’s processing cycles Clock cycle: –Pulse or tick Clock speed: –Number of pulses per second –Measured in hertz (Hz) NEXT SLIDE

15 Cache Memory Small amount of memory located on the CPU chip or near it: –Level 1 –Level 2 Stores recent or frequently used instructions and data Used for quick access by the CPU NEXT SLIDE

16 RAM: The Next Level of Temporary Storage Dynamic RAM (DRAM): –Loses its electrical charge –Needs to be refreshed –SDRAM: Synchronous DRAM –DDR SDRAM Double data rate SDRAM –RDRAM: Rambus DRAM Static RAM (SRAM): –Does not lose its electrical charge –Faster than DRAM –Cache memory NEXT SLIDE

17 Memory and Size Data stored in bytes. Sizes: 1KB – 1 kilobyte means 1024 bytes 1MB – 1 Megabyte, approx. 1 million bytes 1GB – 1 Gigabyte, approx. a thousand MBs. (1,000,000,000 bytes)

18 Bus: –Electrical pathway used to move data between components –Local bus: Connects the CPU with the memory –Expansion bus: Connects the CPU with peripheral devices Buses: The CPU’s Data Highway NEXT SLIDE

19 Bus Performance NEXT SLIDE Bus clock speed: –Rate of speed data moves from one location to another –Measured in Mhz (millions of clock cycles per second) Bus width: –The number of bits of data moved on a bus at any one time –Measured in bits: 16 bits 32 bits

20 Types of Expansion Buses NEXT SLIDE ISA and EISA: –Found on older computers –Connects mouse, modem, and sound card PCI: –Faster than ISA and EISA –Found on modern computers –Connects network, modem, and sound card AGP: –Used for three-dimensional graphics –Connects the graphics card and memory

21 Making Computers Faster Pipelining: –The CPU processes more than one instruction at a time FetchDecodeExecuteStore FetchDecodeExecuteStore Instruction 1 Instruction 2 Non-pipelined CPU FetchDecodeExecuteStore FetchDecodeExecuteStore FetchDecodeExecuteStore FetchDecodeExecuteStore Instruction 1 Instruction 2 Instruction 3 Instruction 4 Pipelined CPU NEXT SLIDE

22 Making Computers Faster Dual processing: –Two CPUs on the same system –Each processor shares the workload Parallel processing: –Network of computers –Each computer works on a portion of the problem simultaneously Dual processors NEXT SLIDE