Data Manipulation

Chih-Wei Tang (唐唐唐唐 之之之之 瑋瑋瑋瑋)

Department of Communication Engineering

National Central University

JhongLi, Taiwan

C.E., NCU, Taiwan 2

Outline

� Computer Architecture

� Machine Language

� Program Execution

� Arithmetic/Logic Instructions

� Communicating with Other Devices

C.E., NCU, Taiwan 3

Computer Architecture

� Central Processing Unit (CPU) or processor� arithmetic/Logic Unit (ALU): perform data manipulation

� control Unit: coordinate the machine’s activities

� registers: temporary storage of information

� general purpose registers

� a temporary holding places for data being manipulated by the CPU

� Inputs to the ALU circuitry

� Results produced by ALU circuitry

� special-purpose registers

� cache Memory

� Bus

� Motherboard

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Cache Memory

� Cache memory

� keep a copy of that portion of main

memory that is of current interest

� register ��cache memory

� CPU can execute more rapidly

� update main memory if data change

� Main memory: data that will be needed in

the near future

� Mass storage: data that will likely not be

needed in the near future

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CPU & Main Memory

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Adding Values Stored in Memory

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Outline

� Computer Architecture

� Machine Language

� Program Execution

� Arithmetic/Logic Instructions

� Communicating with Other Devices

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Machine Language

� Machine instruction = an instruction coded as a bit pattern directly recognizable by the CPU

� Machine language = the set of all instructions recognized by a machine

� Reduced Instruction Set Computing (RISC)� CPU executes minimal set of machine instructions

� few, simple, efficient, and fast instructions

� example: PowerPC from Apple/IBM/Motorola

� Complex Instruction Set Computing (CISC)� CPU executes a large number of complex instructions, even though man of them are technically redundant

� the more complex CPU is easier to program

� example: Pentium from Intel

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Machine Instruction Types –

Data Transfer

� Copy data between CPU and main memory

� LOAD : fill a general-purpose register with the contents of a memory cell

� STORE : transfer the contents of a register to a memory cell

� I/O instructions : communicating with devices outside the CPU-main memory context (printers,

keyboards, monitors, disk drives, etc.)

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Machine Instruction Types –

Arithmetic/Logic

� Use existing data values to compute a new

data value

� Tell the control unit to request an activity

within the arithmetic/logic unit

� AND, OR, and XOR

� SHIFT : the bits that fall off the end of the register are discarded

� ROTATE : fill the holes left at the other end

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Machine Instruction Types – Control

� Direct the execution

of the program rather

than the

manipulation of data

� JUMP

� unconditional jumps

� conditional jumps

Dividing Values Stored in Memory

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A Machine Instruction

� Op-code: specifies which machine operation to

execute

� one per instruction

� Operand: more detailed information about this

operation

� number of operands varies depending on op-code

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Decoding The Instruction 35A7

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Outline

� Computer Architecture

� Machine Language

� Program Execution

� Arithmetic/Logic Instructions

� Communicating with Other Devices

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Program Execution

� Controlled by two special-purpose registers

within CPU

� program counter : address of next instruction

� instruction register : current instruction

� Machine cycle: 3 steps performed by control

unit

� fetch

� decode

� execute

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A Machine Cycle

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Special Case –

Decoding the Instruction B258

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Stored Program Concept

� A program is just a special type of data!

� a program can be encoded and stored in main

memory

� the control unit extracts the program from

memory, decode the instructions, and execute

them

� The machine alone don’t know what is data

and what is program

� The computer just executes according to the

program counter

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The Program Stored in Main Memory

Ready for Execution

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Performing the Fetch Step of the

Machine Cycle (1/2)

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Performing the Fetch Step of the

Machine Cycle (2/2)

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Outline

� Computer Architecture

� Machine Language

� Program Execution

� Arithmetic/Logic Instructions

� Communicating with Other Devices

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Arithmetic/Logic Operations

� Logic: AND, OR, XOR

� Rotate and Shift

� circular shift

� logical shift : discard the bit that falls off the edge

and always fill the hole with a 0

� arithmetic shift : leave the sign bit unchanged

� Arithmetic: add, subtract, multiply, divide

� separate instructions for different types of data

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Outline

� Computer Architecture

� Machine Language

� Program Execution

� Arithmetic/Logic Instructions

� Communicating with Other Devices

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Controllers Attached to a Machine’s

Bus

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Controller

� Intermediary device : it handles communication

between the computer and a device

� Physical form of a circuit board : it plugs into a slot

on the computer’s motherboard

� Format conversion : between a computer and a

particular type of peripheral device

� Port = set of addresses assigned to a controller

� memory-mapped I/O : computer’s I/O devices

appear to be in various memory locations

� buses contain a signal : indicates whether the

message is for a controller or memory

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A Conceptual Representation of

Memory-Mapped I/O

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Communicating with Other Devices

� Direct memory access (DMA)� a controller accesses main memory over the bus

� CPU is not using the bus

� CPU continues with other tasks while the controller performs read/write

� Von Neumann bottleneck: the CPU and the controllers compete for bus access� von Neumann architecture: a computer design model that uses a single storage structure to hold both instructions and data

� coordination of these activities is a major design issue

� Handshaking� 2-way dialogue

� the computer and the peripheral device exchange device’s status and coordinate their activities

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Data Communication Rates

� Measurement units� bps = bits per second

� Kbps = kilo-bps, or 1,000 bps

� Mbps = mega-bps, or 1,000,000 bps

� Gbps = giga-bps, or 1,000,000,000 bps

� Bandwidth = maximum available rate� depends on the type of communication path

and the technology used in its implementation

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Data Communication Path Types

� Parallel communication� several lines transfer different bits simultaneously

� rapid

� complex communication path

� example: CPU �� peripheral devices (e.g., printers)

� rates: > Mbps

� Serial communication� one line transfers one bit at a time

� slower

� communication between different computers

� example : telephone line

� modem : bit patterns (source) � audible tones � bit patterns (destination) (D/A � A/D)