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Chapter 2: Computer Systems Organization

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VAX computer system. Epitome of CISC. Very high-level ISA instruction set ... Allows parallel access to separate disks. Provides for data redundancy. 6 levels ... – PowerPoint PPT presentation

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Title: Chapter 2: Computer Systems Organization


1
Chapter 2 Computer Systems Organization
  • CS 271 Computer Architecture
  • Indiana University Purdue University Fort Wayne

2
Review of computer organization
  • Processors
  • Primary memory
  • Secondary memory
  • Input / Output

3
Processor topics
  • Basic bus-oriented computer
  • CPU organization
  • Fetch-execute cycle
  • RISC
  • Instruction-level parallelism
  • Processor-level parallelism

4
Basic bus-oriented computer
The bus, physically, is just parallel wires It is
controlled by a bus arbiter device
5
CPU organization
  • Data path
  • Part of the CPU
  • Registers
  • ALU
  • Internal buses
  • Data path cycle
  • ALU
  • , -, /,
  • AND, OR, NOT
  • Registers
  • PC, IR, MAR, MBR
  • General purpose
  • Special purpose

6
Fetch-execute cycle
  • 1. Fetch the next instruction from the memory
    location referred to by the PC register and place
    it in the IR
  • 2. Increment the PC
  • 3. Decode the instruction in the IR register
  • 4. Calculate any memory operand address and place
    it in the MAR register
  • 5. Fetch any operand from memory and place in the
    MBR register
  • 6. Execute the instruction
  • 7. Repeat until the HALT instruction is executed

7
RISC vrs. CISC
  • RISC (Reduced Instruction Set Computer)
  • CISC (Complex Instruction Set Computer)
  • Microarchitecture interpretation (CISC) dominated
    until the 1980s
  • VAX computer system
  • Epitome of CISC
  • Very high-level ISA instruction set
  • RISC is favored by faster memory and cache
    technology

8
RISC design principles
  • Avoid microinterpretion
  • Use pipelining to increase throughput
  • This may require out-of-order execution
  • Make instructions simple
  • Few formats
  • Fixed lengths
  • Few operands
  • Only LOAD and STORE instructions should reference
    memory
  • Have many registers

9
Instruction-level parallelism
  • Pipelining
  • Superscalar architecture

10
Pipelining
  • Production line with stages
  • Latency
  • Time to execute one instruction
  • Processor bandwidth
  • The number of MIPS (Millions of Instructions Per
    Second)
  • Note that the results from one instruction may be
    needed by the next instruction

11
Pipelining
A five-stage pipeline
12
Superscalar architecture
  • Pipeline bottleneck is the execute stage
  • Introduce multiple functional units for this stage

13
Processor-level parallelism
  • Array and vector computers
  • SIMD
  • Multiprocessor
  • MIMD
  • Many CPUs
  • Shared memory
  • Multicomputer
  • MIMD
  • Each has its own . . .
  • CPU
  • Local memory

14
Primary memory
  • Cell
  • Smallest addressable unit
  • k-bit cell
  • 2k different bit combinations
  • Usually . . .
  • k 8
  • Cell 1 byte

15
Primary memory organization
16
Primary memory
  • Word
  • Group of cells acted upon as a unit
  • 32-bit word ( 4 bytes) is typical
  • 64-bit words are available
  • Intel Itanium processor
  • IBM and Apple PowerPC G5 processor
  • Register size defines the word size

17
Primary memory
  • Bytes within words might be arranged in big
    endian order or in little endian order

18
Cache memory
  • Just one CPU cycle per memory cycle would slow
    the CPU considerably
  • So, keep heavily used cells in a special fast
    cache memory
  • Before fetching a cell from memory, check if it
    is in the cache

19
Cache memory
  • Cache miss?
  • Bring in an entire cache line
  • Cache line is typically 64 contiguous bytes
  • Principle of locality
  • Memory references made during a short period of
    time tend to cluster around a few memory
    locations
  • Consider . . .
  • a tight loop in a program
  • local variables in a method

20
Multilevel cache memory
CPU
cache
tertiary cache
primary memory
secondary cache
21
Memory packaging
  • SIMM (Single Inline Memory Module)
  • A group of chips (typically 8 or 16) is mounted
    on a circuit board with connectors

22
Primary / secondary memory hierarchy
faster more expensive smaller capacity
slower cheaper larger capacity
23
Winchester disk
  • Sealed hard disk
  • Rotation speed typically 7200 rpm
  • About 5000 to 10,000 concentric tracks per cm
  • About 100,000 bits per cm around circumference

sectors
read-write head
track
24
Winchester disk portion of disk track
25
Winchester disk - multiplatter configuration
26
Winchester disk - multiplatter configuration
  • All the tracks at a given radial distance are
    called a cylinder

boom
cylinder
27
Winchester disk speed
  • Seek time
  • Time for the head to move to desired track
  • About 5 10 msec
  • Latency time
  • Time for the disk to spin around to the desired
    sector
  • About 4 msec at 7200 rpm
  • Transfer time
  • Time to read or write a sector
  • Less than 0.1 msec

28
Floppy disk
  • IDE
  • Integrated Drive Electronics
  • Controller on drive unit
  • Low cost
  • SCSI
  • Small Computer System Interface
  • Pronounced scuzzy
  • Fast, high end
  • Possible to daisy-chain SCSI devices

29
RAID
  • Redundant Array of Inexpensive Disks
  • Allows parallel access to separate disks
  • Provides for data redundancy
  • 6 levels
  • 0 no redundancy
  • 1 each disk has backup
  • Reading is from the quickest disk
  • Writing must be done to both disks
  • 2 3 one bit of data per disk
  • High throughput
  • Error correction
  • Strip string of sectors

30
RAID levels 0 through 6
31
CD-ROM

32
CD-ROM
  • Constant streaming rate
  • 120 cm per sec (single speed)
  • Rotation rate not constant
  • 530 200 rpm
  • Symbol
  • Represents 1 byte
  • Requires 14 bits
  • Error correction included
  • Uses the extra 6 bits

33
CD-ROM
  • Symbols are organized into frames and frames into
    sectors
  • Frame
  • Uses 42 symbols
  • Represents only 24 bytes of data
  • Sector
  • 98 frames
  • Represents only 2048 bytes of data

34
CD-ROM
35
CD-ROM
  • Capacity
  • About 650 MB
  • Access rate (32X)
  • Less than 5 MB per second
  • Seek time
  • Greater than 100 msec
  • Varieties CD-R, CD-RW, DVD, Blu-Ray, etc.

36
Input / Output
  • I/O devices connect indirectly to the system bus
  • System bus is located on the motherboard
  • Motherboard contains . . .
  • CPU
  • SIMM sockets
  • Other chips
  • System bus with sockets for edge connectors of
    boards
  • Board
  • Usually the controller of a device
  • Device
  • Typically connected to board by a ribbon cable

37
I/O devices
38
System bus
  • Bus arbiter
  • Chip on motherboard
  • Grants access to the system bus
  • Device controllers compete with the CPU for bus
    access
  • Preference goes to devices over the CPU
  • This is called cycle stealing

39
System bus
  • Example - DMA (Direct Memory Access)
  • Disk controller transfers a block of data between
    memory and disk without CPU intervention
  • Competes with the CPU for bus (and memory) access
  • Sends interrupt to the CPU when done
  • In response, the CPU runs an interrupt handler to
    update operating system records

40
Typical system buses
  • Original IBM PC bus
  • 62 lines
  • 8 bits per transfer
  • ISA (Industry Standard Architecture) bus
  • Bus for the IBM PC/AT (Intel 286)
  • 98 lines
  • EISA bus
  • ISA with more lines for 32-bit transfers
  • PCI bus
  • Peripheral Component Interconnect
  • USB
  • Universal Serial Bus

41
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42
I/O Devices
  • Keyboard
  • Interrupt generated whenever key is pressed or
    released
  • Mouse
  • Sends 3 bytes whenever it moves
  • Change in x
  • Change in y
  • Button state

43
I/O Devices
  • Monitor
  • CRT and flat panel
  • Terminals are character map or video map
  • Character map terminal
  • Renders characters on the screen
  • Holds lines of character codes
  • 25 lines x 80 characters per line 2000 codes
  • Plus 2000 attributes
  • So, a character map video memory requires 4000
    bytes

44
I/O Devices
  • Monitor (continued)
  • Bit map terminal
  • VGA (early standard)
  • 640pixels x 480 pixels 307,200 pixels
  • Software renders characters in pixels
  • Color uses 8, 16, 24, or 32 bits per pixel
  • Video ram memory
  • Holds the bit map
  • 5.5 MB for 1600 x 1200 _at_ 3 bytes / pixel
  • Video display
  • Requires huge bandwidth 137.5 MB/sec
  • AGP (Accelerated Graphics Port) bus

45
I/O Devices
  • Printer
  • Dot matrix
  • Old technology
  • Inkjet
  • Laser
  • Gray scale
  • Implemented with halftone technique
  • Color
  • Printed with cyan, yellow, magenta, and black ink
    (CYMK)
  • Monitors use RGB instead

46
Telecommunications
  • RS-232-C interface
  • RS-232-C is a standard computer-terminal
    interface
  • It is a protocol and specification for sending
    signals
  • When a telephone line is used to connect a
    computer and a terminal, two modems are needed .
    . .
  • Between the computer and telephone line
  • Between the telephone line and terminal

47
Telecommunications
  • Modem
  • MOdulator DEModulator
  • For communication over telephone lines
  • Uses a UART chip
  • Universal Asynchronous Receiver Transmitter
  • Converts parallel (byte stream) to serial (bits
    stream) and back
  • Analog telephone signal is modulated
  • Amplitude
  • Frequency
  • Phase
  • Supports full-duplex
  • Simultaneous transmission in both directions

48
Various modulation techniques
Modulation by (a) Two-level signal (b)
Amplitude modulation (c) Frequency modulation
and (d) Phase modulation
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