Introduction to Computer Science. William Hsu Department of Computer Science and Engineering National Taiwan Ocean University

Transcription

1 Introduction to Computer Science William Hsu Department of Computer Science and Engineering National Taiwan Ocean University

2 Chapter 2: Data Manipulation The successor to Intel's Haswell CPU technology, "Broadwell", has been revealed and shown working here at the Intel Developer Forum in San Francisco. The chip is built using a whole new production process that shrinks Haswell's 22nm transistors down to 14nm. That is tiny.

3 2.1 Computer Architecture 2.2 Machine Language 2.3 Program Execution 2.4 Arithmetic/Logic Instructions 2.5 Communicating with Other Devices 2.6 Program Data Manipulation 2.7 Other Architectures

4 Computer Architecture Central Processing Unit (CPU) or processor Arithmetic/Logic unit versus Control unit. Registers General purpose. Special purpose. AMD s world #1 5GHz CPU. 2014/8/29 4

5 CPU and Main Memory Connected via a Bus 2014/8/29 5

6 Computer Architecture Bus. Motherboard. 2014/8/29 6

7 Intel 4004 Schematics 2014/8/29 7

8 Intel Core i7 3770k 2014/8/29 8

9 Processor Speed over Time 2014/8/29 9

10 IO Bridges Northbridge is connected directly to the CPU via the frontside bus (FSB) Responsible for tasks that require the highest performance. Southbridge, also known as I/O controller hub. 2014/8/29 10

11 Block diagrams 2014/8/29 11

12 Stored Program Concept A program can be encoded as bit patterns and stored in main memory. From there, the CPU can then extract the instructions and execute them. In turn, the program to be executed can be altered easily. 2014/8/29 12

13 Terminology Machine instruction: An instruction (or command) encoded as a bit pattern recognizable by the CPU. Machine language: The set of all instructions recognized by a machine. 2014/8/29 13

14 Machine Language Philosophies Reduced Instruction Set Computing (RISC) Few, simple, efficient, and fast instructions. Examples: PowerPC from Apple/IBM/Motorola and ARM. Complex Instruction Set Computing (CISC) Many, convenient, and powerful instructions. Example: Intel. 2014/8/29 14

15 CISC vs RISC CISC Has more complex hardware. More compact software code. Takes more cycles per instruction. Can use less RAM as no need to store intermediate results. RISC Has simpler hardware. More complicated software code. Takes one cycle per instruction. Can use more RAM to handle intermediate results. 2014/8/29 15

16 Machine Instruction Types Data Transfer: copy data from one location to another. Arithmetic/Logic: use existing bit patterns to compute a new bit patterns. Control: direct the execution of the program. 2014/8/29 16

17 Registers /8/29 17

18 Registers (core ix, 64bit) 2014/8/29 18

19 Adding Values Stored in Memory 2014/8/29 19

20 Dividing Values Stored in Memory 2014/8/29 20

21 The Architecture of the Machine Described in Appendix C 2014/8/29 21

22 Parts of a Machine Instruction Op-code: Specifies which operation to execute. Operand: Gives more detailed information about the operation. Interpretation of operand varies depending on op-code. 2014/8/29 22

23 The Composition of an Instruction for the Machine in Appendix C 2014/8/29 23

24 Decoding the Instruction 35A7 2014/8/29 24

25 An Encoded Version of the Instructions in Figure /8/29 25

26 Program Execution Controlled by two special-purpose registers: Program counter: address of next instruction. Instruction register: current instruction. Machine Cycle Fetch Decode Execute (Store) 2014/8/29 26

27 Decoding the Instruction B /8/29 27

28 The Program from Figure 2.7 Stored in Main Memory Ready for Execution 2014/8/29 28

29 Performing the Fetch Step of the Machine Cycle 2014/8/29 29

30 Performing the Fetch Step of the Machine Cycle (continued) 2014/8/29 30

31 Endian Order Depending on which computing system you use, you will have to consider the byte order in which multi-byte numbers are stored, particularly when you are writing those numbers to a file. The two orders are called Little Endian and Big Endian. 31

32 Little Endian (1) Little Endian means that the low-order byte of the number is stored in memory at the lowest address, and the high-order byte at the highest address. (The little end comes first.) For example, a 4 byte long int Byte3 Byte2 Byte1 Byte0 will be arranged in memory as follows: Base Address+0 Base Address+1 Base Address+2 Base Address+3 Byte0 Byte1 Byte2 Byte3 Intel processors (those used in PC's) use "Little Endian" byte order. 32

33 Little Endian (2) 33

34 Big Endian Big Endian means that the high-order byte of the number is stored in memory at the lowest address, and the low-order byte at the highest address. (The big end comes first.) Base Address+0 Byte3 Base Address+1 Base Address+2 Byte2 Byte1 Base Address+3 Byte0 Motorola processors (those used in Mac's) use "Big Endian" byte order. 34

35 Arithmetic/Logic Operations Logic: AND, OR, XOR Masking Rotate and Shift: circular shift, logical shift, arithmetic shift Arithmetic: add, subtract, multiply, divide Precise action depends on how the values are encoded (two s complement versus floating-point). 2014/8/29 35

36 Rotating the Bit Pattern 65 h (hexadecimal) One Bit to the Right 2014/8/29 36

37 Communicating with Other Devices Controller: An intermediary apparatus that handles communication between the computer and a device. Specialized controllers for each type of device General purpose controllers (USB and FireWire) Port: The point at which a device connects to a computer Memory-mapped I/O: CPU communicates with peripheral devices as though they were memory cells 2014/8/29 37

38 Controllers Attached to a Machine s Bus 2014/8/29 38

39 A Conceptual Representation of Memory- Mapped I/O 2014/8/29 39

40 Communicating with Other Devices (continued) Direct memory access (DMA): Main memory access by a controller over the bus. Von Neumann Bottleneck: Insufficient bus speed impedes performance. Handshaking: The process of coordinating the transfer of data between components. 2014/8/29 40

41 Communicating with Other Devices (continued) Parallel Communication: Several communication paths transfer bits simultaneously. Serial Communication: Bits are transferred one after the other over a single communication path. 2014/8/29 41

42 Communicating with Other Devices (continued) Universal serial bus (USB) Thunderbolt 2014/8/29 42

43 Transfer speed: USB vs Thunderbolt 2014/8/29 43

44 Anything faster? InfiniBand (abbreviated IB) is a computer-networking communications standard used in high-performance computing that features very high throughput and very low latency. Data interconnection, switches, storage server connections. 2014/8/29 44

45 Infiniband speed 2014/8/29 45

46 Serial attached SCSI Serial Attached SCSI (SAS) is a point-to-point serial protocol that moves data to and from computer-storage devices such as hard drives and tape drives. Replaces the older Parallel SCSI (Parallel Small Computer System Interface ("scuzzy") bus technology in mid 1980s. SAS offers optional compatibility with Serial ATA (SATA), versions 2 and later. This allows the connection of SATA drives to most SAS backplanes or controllers. The reverse, connecting SAS drives to SATA backplanes, is not possible 2014/8/29 46

47 External SAS connectors 2014/8/29 47

48 Serial attached SCSI 2014/8/29 48

49 Data Communication Rates Measurement units: Bps: Bits per second Kbps: Kilo-bps (1,000 bps) Mbps: Mega-bps (1,000,000 bps) Gbps: Giga-bps (1,000,000,000 bps) Bandwidth: Maximum available rate. 2014/8/29 49

50 Communication Speed over the Years 2014/8/29 50

51 Programming Data Manipulation Programing languages shields users from details of the machine: A single Python statement might map to one, tens, or hundreds of machine instructions. Programmer does not need to know if the processor is RISC or CISC. Assigning variables surely involves LOAD, STORE, and MOVE op-codes. 2014/8/29 51

52 Bitwise Problems as Python Code print(bin(0b & 0b )) # Prints '0b ' print(bin(0b b )) # Prints '0b ' print(bin(0b ^ 0b )) # Prints '0b ' 2014/8/29 52

53 Control Structures If statement: if (water_temp > 140): print('bath water too hot!') While statement: while (n < 10): print(n) n = n /8/29 53

54 Functions Function: A name for a series of operations that should be performed on the given parameter or parameters Function call: Appearance of a function in an expression or statement x = 1034 y = 1056 z = 2078 biggest = max(x, y, z) print(biggest) # Prints '2078' 2014/8/29 54

55 Functions (continued) Argument Value: A value plugged into a parameter. Fruitful functions return a value. void functions, or procedures, do not return a value. sidea = 3.0 sideb = 4.0 # Calculate third side via Pythagorean Theorem hypotenuse = math.sqrt(sidea**2 + sideb**2) print(hypotenuse) 2014/8/29 55

56 Input / Output # Calculates the hypotenuse of a right triangle import math # Inputting the side lengths, first try sidea = int(input('length of side A? ')) sideb = int(input('length of side B? ')) # Calculate third side via Pythagorean Theorem hypotenuse = math.sqrt(sidea**2 + sideb**2) print(hypotenuse) 2014/8/29 56

57 Marathon Training Assistant # Marathon training assistant. import math # This function converts a number of minutes and # seconds into just seconds. def total_seconds(min, sec): return min * 60 + sec # This function calculates a speed in miles per hour given # a time (in seconds) to run a single mile. def speed(time): return 3600 / time 2014/8/29 57

58 Marathon Training Assistant (continued) # Prompt user for pace and mileage. pace_minutes = int(input('minutes per mile? ')) pace_seconds = int(input('seconds per mile? ')) miles = int(input('total miles? ')) # Calculate and print speed. mph = speed(total_seconds(pace_minutes, pace_seconds)) print('your speed is ' + str(mph) + ' mph') # Calculate elapsed time for planned workout. total = miles * total_seconds(pace_minutes, pace_seconds) elapsed_minutes = total // 60 elapsed_seconds = total % 60 print('your elapsed time is ' + str(elapsed_minutes) + ' mins ' + str(elapsed_seconds) + ' secs') 2014/8/29 58

59 Example Marathon Training Data Time Per Mile Total Elapsed Time Minutes Seconds Miles Speed (mph) Minutes Seconds /8/29 59

60 Other Architectures Technologies to increase throughput: Pipelining: Overlap steps of the machine cycle. Superscalar: Multiple instructions per cycle. Parallel Processing: Use multiple processors simultaneously SISD: No parallel processing MIMD: Different programs, different data SIMD: Same program, different data MISD? 2014/8/29 60

61 Parallel Processing 2014/8/29 61

62 Pipelining 2014/8/29 62

63 Data Hazards 2014/8/29 63

64 Superscalar 2014/8/29 64

65 Design and power consumption 2014/8/29 65