Computer system organization

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Computer system organization

• Computer Architecture
• From microcontrollers to supercomputers

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Von Newmann machine
Von Newmann Invented EDSAC (1949). First Stored
Program Computer. Importance We are
still using the same basic design.
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Computer Architecture coverage

• Coordination of many levels of abstraction
• Under a rapidly changing set of forces
• Design, Measurement, and Evaluation

Application
Operating
System
Compiler
Firmware
I/O system
Instr. Set Proc.
Instruction Set Architecture
Datapath Control
Digital Design
Circuit Design
Layout
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Original food chain in computer architecture
Big Fishes Eating Little Fishes
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1988 Computer Food Chain
Mainframe
PC
Work- station
Mini- computer
Mini- supercomputer
Supercomputer
Massively Parallel Processors
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1998 Computer Food Chain
Mini- supercomputer
Mini- computer
Massively Parallel Processors
Mainframe
PC
Work- station
Server
Now who is eating whom?
Supercomputer
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Why mini-computer disappeared? Microprocessor
Performance
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What are left and what new in 2002

• 2002
• Powerful PCs and SMP Workstations
• Network of SMP Workstations
• Mainframes
• Supercomputers
• Embedded Computers

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Microcontroller

• A smaller computer
• On-chip RAM, ROM, I/O ports...
• ExampleMotorolas 6811, Intels 8051, Zilogs
  Z80 and PIC 16X

RAM
ROM
CPU
A single chip
Serial COM Port
I/O Port
Timer
Microcontroller
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Interconnection
External interrupts
On-chip ROM for program code
Timer/Counter
Interrupt Control
Timer 1
On-chip RAM
Counter Inputs
Timer 0
CPU
Serial Port
Bus Control
4 I/O Ports
OSC
TxD RxD
P0 P1 P2 P3
Address/Data
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Microprocessor vs. Microcontroller

• Microprocessor
• CPU is stand-alone, RAM, ROM, I/O, timer are
  separate
• designer can decide on the amount of ROM, RAM
  and I/O ports.
• expansive
• versatility
• general-purpose

• Microcontroller
• CPU, RAM, ROM, I/O and timer are all on a single
  chip
• fix amount of on-chip ROM, RAM, I/O ports
• for applications in which cost, power and space
  are critical
• single-purpose

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Embedded System

• Embedded system means the processor is embedded
  into that application.
• An embedded product uses a microprocessor or
  microcontroller to do one task only.
• In an embedded system, there is only one
  application software that is typically burned
  into ROM.
• Exampleprinter, keyboard, video game player

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Embedded Systems

• Account for gt99 of new microprocessors
• Consumer electronics
• Vehicle control systems
• Medical equipment
• Sensor networks

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Definitions

• Embedded system Almost any special-purpose
  computer
• I.e. not a PC, workstation, or server box
• Microcontroller small system on a chip,
  contains extra logic to help talk to the real
  world in real time

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Embedded Characteristics

• Close interaction with the physical world
• Often must operate in real time
• Constrained resources
• Memory
• SRAM, DRAM, flash, EPROM,
• Power
• CPU cycles

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More Characteristics

• Often there is no
• Virtual memory
• Memory protection
• Hardware supported user-kernel boundary
• Secondary storage
• Hard to upgrade once deployed
• Cost sensitive
• Per-unit cost can dominate overall cost

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CPU Design Space

• 4-bit microcontroller
• Typically costs a few
• Few bytes of RAM
• No OS
• Software all in assembly
• These are getting less popular
• 8-bit microcontroller
• A few bytes to a few hundred KB of RAM
• At the small end software is in asm, at the high
  end C, C, Java
• Might run a home-grown OS, might run a commercial
  RTOS

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CPU Design Space 2

• 16- and 32-bit microcontrollers
• Few KB to many MB of RAM
• Usually runs an RTOS vxWorks, WinCE, QNX,
  ucLinux,
• May or may not have caches
• Wide range of costs

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Programming Languages

• Assembler
• No space overhead
• Good programmers write fast code
• Non-portable
• Hard to debug
• C
• Little space and time overhead
• Somewhat portable
• Good compilers exist

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More Languages

• C
• Often used as a better C
• Low space and time overhead if used carefully
• Java
• More portable
• Full Java requires lots of RAM
• J2ME popular on cell-phone types of devices
• Bad for real-time!

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RTOS

• Low end Not much more than a threads library
• High end Not much smaller than Linux or WinXP
• Important
• Predictability
• Reliability
• Efficiency

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Creating Embedded SW

• Pick
• Cheapest CPU that seems like itll work
• Appropriate language
• Appropriate OS
• Appropriate software architecture
• Code test repeat

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• Supercomputer

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Multiprocessors

• Idea create powerful computers by connecting
  many smaller ones
• good news works for timesharing
• bad news its really hard to write good
  concurrent programs
• many commercial failures

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IBM Bluegene
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System Overview

• Number of nodes 65,536 64X32X32
• Each node as a single ASIC processor and a
  memory
• 2GB of SDRAM-DDR memory
• System Packaging
• 2 nodes per compute card
• 16 compute cards per node board
• 16 node boards per 512-node mid-plane
• 2 mid-planes in a 1024-node rack
• 64 such node racks

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Cluster and grid systems
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ClusterIf one system goes down (e.g.
Manufacturing) then this task is picked up by
another system (e.g. Administration)
Administration
Shared disk
Shared disk
Manufacturing
Shared disk
Distribution
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Example- web server
Popular web servers employ clusters.When
serving the Olympics in Nagano IBM had this kind
of configuration with 53 servers.
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Trends that promote clusters

• Very high-performance microprocessors, i.e. the
  need for massive parallelism is decreasing
• The need for high availability is increasing
• The communication technology is improving
  rapidly, e.g. fiber channels, Gbit networks etc.
• Standard tools and protocols for distributed
  computing, e.g. TCP/IP

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Clusters versus SMPs

• Clusters are composed of whole computers, SMPs
  are composed of processors
• Compared to a SMP it is easier to obtain high
  availabilty in clusters
• Compared to a SMP it is easier to incrementally
  increase the size of a cluster
• SMPs are easier to maintain from a system
  administrators point of view
• On a SMP you will often get away with only one
  license for your favorite software

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GRID cluster node
Remote Fabric
WAN
Gigabit long-haul link
CPU Servers
Multi-gigabit LAN
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Forces on Computer Architecture
Technology
Programming
Languages
Applications
Computer Architecture
Operating
Systems
History
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What is an architect doing

• Types of Bridges

Truss (Forth Bridge, Scotland)
Suspension (Golden Gate Bridge, California)
Cable-stayed (Higashi Kobe, Japan)