1.Organization

8/3/2019 1.Organization

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Computer OrganizationComputer Organization

Hardware and Software


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Computing SystemsComputing SystemsComputers have two kinds of components:Computers have two kinds of components:

HardwareHardware, consisting of its physical devices, consisting of its physical devices(CPU, memory, bus, storage devices, ...)(CPU, memory, bus, storage devices, ...)

SoftwareSoftware, consisting of the programs it has, consisting of the programs it has(Operating system, applications, utilities, ...)(Operating system, applications, utilities, ...)


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Hardware: CPUHardware: CPUCentral Processing Unit (CPU):Central Processing Unit (CPU):

the brain of the machinethe brain of the machine

location of circuitry that performs arithmetic andlocation of circuitry that performs arithmetic andlogical ML statementslogical ML statements

measurement: speed (roughly) in megahertzmeasurement: speed (roughly) in megahertz

(millions of clock(millions of clock--ticks per second)ticks per second) examples: Intel Pentium, AMD K6, Motorolaexamples: Intel Pentium, AMD K6, Motorola

PowerPC, Sun SPARC,PowerPC, Sun SPARC,


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Hardware: RAMHardware: RAMRandom Access Memory (RAM)Random Access Memory (RAM)

main memory, which is fast, butmain memory, which is fast, but volatilevolatile......

analogous to a persons shortanalogous to a persons short--term memory.term memory.

many tiny onmany tiny on--off switches: for convenienceoff switches: for convenience

on is represented by 1, off by 0.on is represented by 1, off by 0.

each switch is called aeach switch is called a bbinary diginary digitit, or, or bitbit..

8 bits is called a8 bits is called a bytebyte..

221010 bytes =1024 bytes is called abytes =1024 bytes is called a kilobytekilobyte (1K)(1K)

222020 bytes is called abytes is called a megabytemegabyte (1M).(1M).


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Hardware (Disk)Hardware (Disk)Secondary Memory (Disk):Secondary Memory (Disk):

Stable storage using magnetic or optical media.Stable storage using magnetic or optical media.

Analogous to a persons longAnalogous to a persons long--term memory.term memory.

Slower to access than RAM.Slower to access than RAM.

Examples:Examples:

floppy disk (measured in kilobytes)floppy disk (measured in kilobytes)

hard disk (measured in gigabytes (2hard disk (measured in gigabytes (23030 bytes))bytes))

CDCD--ROM (measured in megabytes), ...ROM (measured in megabytes), ...


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Hardware: the BusHardware: the BusThe Bus:The Bus:

Connects CPU to other hardware devices.Connects CPU to other hardware devices.

Analogous to a persons spinal cord.Analogous to a persons spinal cord.

Speed measured in megahertz (like the CPU),Speed measured in megahertz (like the CPU),but typically much slower than the CPU...but typically much slower than the CPU...

The bottleneck in most of todays PCs.The bottleneck in most of todays PCs.


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Hardware: CacheHardware: CacheWhile accessing RAM is faster than accessingWhile accessing RAM is faster than accessing

secondary memory, it is still quite slow,secondary memory, it is still quite slow,

relative to the rate at which the CPU runs.relative to the rate at which the CPU runs.

To circumvent this problem, most systems addTo circumvent this problem, most systems adda fasta fast cache memorycache memory to the CPU, to storeto the CPU, to store

recently used instructions and data.recently used instructions and data.

(Assumption: Since such instructions/data(Assumption: Since such instructions/datawere needed recently, they will be neededwere needed recently, they will be needed

again in the near future.)again in the near future.)


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Hardware: SummaryHardware: SummaryPutting the pieces together:Putting the pieces together:

CPU

Bus

Main

Memory

Secondary

Memorycache

Programs are stored (longPrograms are stored (long--term) in secondary memory,term) in secondary memory,and loaded into main memory to run, from whichand loaded into main memory to run, from whichthe CPU retrieves and executes their statements.the CPU retrieves and executes their statements.


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Software: OSSoftware: OSTheThe operating systemoperating system (OS) is loaded from(OS) is loaded from

secondary memory into main memory whensecondary memory into main memory when

the computer is turned on, and remains inthe computer is turned on, and remains inmemory until the computer is turned off.memory until the computer is turned off.

RAM DiskCPUCache

Bus

OS


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Software: OSSoftware: OSThe OS acts as the manager of the system,The OS acts as the manager of the system,

making sure that each hardware devicemaking sure that each hardware device

interacts smoothly with the others.interacts smoothly with the others.

It also provides the interface by which theIt also provides the interface by which theuser interacts with the computer, and awaitsuser interacts with the computer, and awaits

user input if no application is running.user input if no application is running.

Examples: MacOS, WindowsExamples: MacOS, Windows--95, Windows95, Windows--NT,NT,UNIX, Linux, Solaris, ...UNIX, Linux, Solaris, ...


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Software: ApplicationsSoftware: ApplicationsApplications are nonApplications are non--OS programs thatOS programs that

perform some useful task, includingperform some useful task, including

word processors, spreadsheets, databases,word processors, spreadsheets, databases,web browsers, C++ compilers, ...web browsers, C++ compilers, ...

Example C++ compilers/environments:Example C++ compilers/environments:

CodeWarrior (MacOS, Win95, WinNT, Solaris)CodeWarrior (MacOS, Win95, WinNT, Solaris)

GNU C++ (UNIX, Linux)GNU C++ (UNIX, Linux)

Turbo/Borland C++ (Win95, WinNT)Turbo/Borland C++ (Win95, WinNT)

Visual C++ (Win95, WinNT)Visual C++ (Win95, WinNT)


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Software: User ProgramsSoftware: User ProgramsPrograms that are neither OS programs norPrograms that are neither OS programs nor

applications are called user programs.applications are called user programs.

User programs are what youll be writing inUser programs are what youll be writing inthis course.this course.


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Putting it all togetherPutting it all togetherPrograms and applications that are not running arePrograms and applications that are not running are

stored on disk.stored on disk.

RAM DiskCPUCache

Bus

OS App


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Putting it all togetherPutting it all togetherWhen you launch a program, the OS controls the CPUWhen you launch a program, the OS controls the CPU

and loads the program from disk to RAM.and loads the program from disk to RAM.

RAM DiskCPUCache

Bus

OS AppAppOS


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Putting it all togetherPutting it all togetherThe OS then relinquishes the CPU to the program,The OS then relinquishes the CPU to the program,

which begins to run.which begins to run.

RAM DiskCPUCache

Bus

OS AppAppApp


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The FetchThe Fetch--Execute CycleExecute CycleAs the program runs, it repeatedly fetches the nextAs the program runs, it repeatedly fetches the next

instruction (from memory/cache), executes it,instruction (from memory/cache), executes it,and stores any results back to memory.and stores any results back to memory.

RAM DiskCPUCache

Bus

OS AppAppApp

Thats all a computer does: fetchThats all a computer does: fetch--executeexecute--store,store,millions of times each secondmillions of times each second!!


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SummarySummaryA computer has two kinds of components:A computer has two kinds of components:

Hardware: its CPU, RAM, Disk(s), ...Hardware: its CPU, RAM, Disk(s), ...

Software, its OS, Applications, and User Programs.Software, its OS, Applications, and User Programs.

1.Organization

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