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Computer Application in Architectures
Computer Application in Architectures
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Computer hardware is a physical components of the computer.
Chapter 1*Software is a general term for the various kinds of
programs used to operate computers and related devices. (The term
hardware describes the physical aspects of computers and related
devices.)
Chapter 1
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Input/OutputLecture 1 - *
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Input/OutputLecture 1 - *Historical Context of Storage and
I/OSecondary and Tertiary Storage DevicesStorage I/O Performance
MeasuresQueuing TheoryProcessor Interface IssuesI/O BusesRedundant
Arrays of Inexpensive Disks (RAID)File SystemsI/O BenchmarksFile
System PerformanceComputer Application in Architectures
Computer Application in Architectures
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Sir Kashif
Chapter 1
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A program that runs on the raw hardware and supportsResource
AbstractionResource SharingAbstracts and standardizes the interface
to the user across different types of hardwareVirtual machine hides
the messy details which must be performedManages the hardware
resourcesEach program gets time with the resourceEach program gets
space on the resourceMay have potentially conflicting goals:Use
hardware efficientlyGive maximum performance to each userChapter
1*
Chapter 1
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First generation: 1945 1955Vacuum tubesPlug boardsSecond
generation: 1955 1965TransistorsBatch systemsThird generation: 1965
1980Integrated circuitsMultiprogrammingFourth generation: 1980
presentLarge scale integrationPersonal computersNext generation:
???Systems connected by high-speed networks?Wide area resource
management?Chapter 1*
Chapter 1
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Run one job at a timeEnter it into the computer (might require
rewiring!)Run itRecord the resultsProblem: lots of wasted computer
time!Computer was idle during first and last stepsComputers were
very expensive!Goal: make better use of an expensive commodity:
computer timeChapter 1*
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Bring cards to 1401Read cards onto input tapePut input tape on
7094Perform the computation, writing results to output tapePut
output tape on 1401, which prints outputChapter 1*
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Original batch systems used tape drivesLater batch systems used
disks for bufferingOperator read cards onto disk attached to the
computerComputer read jobs from diskComputer wrote job results to
diskOperator directed that job results be printed from diskDisks
enabled simultaneous peripheral operation on-line
(spooling)Computer overlapped I/O of one job with execution of
anotherBetter utilization of the expensive CPUStill only one job
active at any given timeChapter 1*
Chapter 1
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Multiple jobs in memoryProtected from one anotherOperating
system protected from each job as wellResources (time, hardware)
split between jobsStill not interactiveUser submits jobComputer
runs itUser gets results minutes (hours, days) laterChapter
1*Operating systemJob 1Job 2Job 3Memory partitions
Chapter 1
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Multiprogramming allowed several jobs to be active at one
timeInitially used for batch systemsCheaper hardware terminals
-> interactive useComputer use got much cheaper and easierNo
more priesthoodQuick turnaround meant quick fixes for problems
Chapter 1*
Chapter 1
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*The creation and deletion of both user and system processesb.
The suspension and resumption of processesc. The provision of
mechanisms for process synchronizationd. The provision of
mechanisms for process communicatione. The provision of mechanisms
for deadlock handling
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Mainframe operating systems: MVSServer operating systems:
FreeBSD, SolarisMultiprocessor operating systems: Cellular
IRIXPersonal computer operating systems: Windows, UnixReal-time
operating systems: VxWorksEmbedded operating systemsSmart card
operating systemsSome operating systems can fit into more than one
categoryChapter 1*
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Chapter 1*Hard drive controllerVideo controllerMemoryUSB
controllerNetwork controllerOutside worldCPUComputer internals
(inside the box)
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Chapter 1*Execute unitExecute unitExecute unitExecute
unitBufferFetch unitDecode unitFetch unitDecode unitFetch
unitDecode unitPipelined CPUSuperscalar CPU
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Goal: really large memory with very low latencyLatencies are
smaller at the top of the hierarchyCapacities are larger at the
bottom of the hierarchySolution: move data between levels to create
illusion of large memory with low latencyChapter 1*Access latency1
ns25 ns50 ns5 ms50 sec< 1 KB1 MB256 MB40 GB> 1
TBCapacityBetterBetter
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Data stored on surfacesUp to two surfaces per platterOne or more
platters per diskData in concentric tracksTracks broken into
sectors256B-1KB per sectorCylinder: corresponding tracks on all
surfacesData read and written by headsActuator moves headsHeads
move in unisonChapter
1*sectorcylinderplatterspindletrackheadactuatorsurfaces
Chapter 1
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Single base/limit pair: set for each processTwo base/limit
registers: one for program, one for dataChapter 1*User program and
dataUser program and dataOperating
systemAddress0x1dfff0x230000x27fff0x2b0000x2ffff0BaseLimitUser
dataUser programOperating systemUser
dataBase1Limit2Limit1Base2Address0x1dfff0x230000x290000x2bfff0x2ffff00x2d0000x24fff
Chapter 1
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Left: sequence as seen by hardwareRequest sent to controller,
then to diskDisk responds, signals disk controller which tells
interrupt controllerInterrupt controller notifies CPURight:
interrupt handling (software point of view)Chapter 1*Interrupt
controllerCPU5Disk controller32614InstructionnOperating
systemInstructionn+1Interrupt handler1: Interrupt2: Process
interrupt3: Return
Chapter 1
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Many of these should be familiar to Unix usersProcesses (and
trees of processes)DeadlockFile systems & directory
treesPipesWell cover all of these in more depth later on, but its
useful to have some basic definitions now
Chapter 1*
Chapter 1
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Process: program in executionAddress space (memory) the program
can useState (registers, including program counter & stack
pointer)OS keeps track of all processes in a process tableProcesses
can create other processesProcess tree tracks these relationshipsA
is the root of the treeA created three child processes: B, C, and
DC created two child processes: E and FD created one child process:
GChapter 1*ABEFCDG
Chapter 1
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Processes have three segmentsText: program codeData: program
dataStatically declared variablesAreas allocated by malloc() or
newStackAutomatic variablesProcedure call informationAddress space
growthText: doesnt growData: grows upStack: grows downChapter
1*StackDataText0x7fffffff0Data
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Chapter 1*Keep track of which parts of memory are currently
being used and by whom.
Decide which processes are to be loaded into memory when memory
s pace become s available.
Allocate and d eallocate memory space as needed.
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Chapter 1*Potential deadlockActual deadlock
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Chapter 1*Root
directorybinfacultygradslspscpcshelmsbrandtkagamer4stuffclassesresearchstuff
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Processes want to exchange information with each otherMany ways
to do this, includingNetworkPipe (special file): A writes into
pipe, and B reads from itChapter 1*AB
Chapter 1
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Programs want the OS to perform a serviceAccess a fileCreate a
processOthersAccomplished by system callProgram passes relevant
information to OSOS performs the service ifThe OS is able to do
soThe service is permitted for this program at this timeOS checks
information passed to make sure its OKDont want programs reading
data into other programs memory!Chapter 1*
Chapter 1
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System call: read(fd,buffer,length)Program pushes arguments,
calls libraryLibrary sets up trap, calls OSOS handles system
callControl returns to libraryLibrary returns to user
programChapter 1*Return to callerTrap to kernelTrap code in
registerIncrement SPCall readPush argumentsDispatchSys call
handlerKernel space (OS)User space00xffffffff139Library (read
call)User code
Chapter 1
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Chapter 1*
CallDescriptionfd = open(name,how)Open a file for reading and/or
writings = close(fd)Close an open filen = read(fd,buffer,size)Read
data from a file into a buffern = write(fd,buffer,size)Write data
from a buffer into a files = lseek(fd,offset,whence)Move the
current pointer for a files = stat(name,&buffer)Get a files
status information (in buffer)s = mkdir(name,mode)Create a new
directorys = rmdir(name)Remove a directory (must be empty)s =
link(name1,name2)Create a new entry (name2) that points to the same
object as name1s = unlink(name)Remove name as a link to an object
(deletes the object if name was the only link to it)
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Chapter 1*
CallDescriptionpid = fork()Create a child process identical to
the parentpid=waitpid(pid,&statloc,options)Wait for a child to
terminates = execve(name,argv,environp)Replace a process core
imageexit(status)Terminate process execution and return statuss =
chdir(dirname)Change the working directorys =
chmod(name,mode)Change a files protection bitss =
kill(pid,signal)Send a signal to a processseconds =
time(&seconds)Get the elapsed time since 1 Jan 1970
Chapter 1
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while (TRUE) {/* repeat forever */ type_prompt( );/* display
prompt */ read_command (command, parameters)/* input from terminal
*/ if (fork() != 0) {/* fork off child process */ /* Parent code */
waitpid( -1, &status, 0);/* wait for child to exit */} else {
/* Child code */ execve (command, parameters, 0);/* execute command
*/ }} Chapter 1*
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Chapter 1*Main procedureService routinesUtility routines
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First widely used in VM/370 with CMSAvailable today in
VMwareAllows users to run any x86-based OS on top of Linux or
NTGuest OS can crash without harming underlying OSOnly virtual
machine failsrest of underlying OS is fineGuest OS can even use raw
hardwareVirtual machine keeps things separatedChapter 1*Bare
hardwareLinuxVMwareLinuxApp1App2App3VMwareVMwareWindows
NTFreeBSDI/O instructionsSystem callsCalls to simulate I/OReal I/O
instructions
Chapter 1
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Processes (clients and OS servers) dont share
memoryCommunication via message-passingSeparation reduces risk of
byzantine failuresExamples include MachChapter 1*MicrokernelClient
processProcess serverTerminal serverClient processFile serverMemory
serverUser modeKernel mode
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Chapter 1*
Exp.NumberPrefixExp.NumberPrefix10-30.001milli1031,000Kilo10-60.000001micro1061,000,000Mega10-90.000000001nano1091,000,000,000Giga10-120.000000000001pico10121,000,000,000,000Tera10-150.000000000000001femto10151,000,000,000,000,000Peta10-180.000000000000000001atto10181,000,000,000,000,000,000Exa
Chapter 1
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Bubble sort, also known as sinking sort, is a simple sorting
algorithm that works by repeatedly stepping through the list to be
sorted, comparing each pair of adjacent items and swapping them if
they are in the wrong order.
A bubble sort, a sorting algorithm that continuously steps
through a list, swapping items until they appear in the correct
order.
Chapter 1
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Chapter 1
Let us take the array of numbers "5 1 4 2 8", and sort the array
from lowest number to greatest number using bubble sort algorithm.
In each step, elements written in bold are being compared.
First Pass:( 5 1 4 2 8 ) ( 1 5 4 2 8 ), Here, algorithm compares
the first two elements, and swaps them.( 1 5 4 2 8 ) ( 1 4 5 2 8 ),
Swap since 5 > 4( 1 4 5 2 8 ) ( 1 4 2 5 8 ), Swap since 5 >
2( 1 4 2 5 8 ) ( 1 4 2 5 8 ), Now, since these elements are already
in order (8 > 5), algorithm does not swap them.Second Pass:( 1 4
2 5 8 ) ( 1 4 2 5 8 )( 1 4 2 5 8 ) ( 1 2 4 5 8 ), Swap since 4 >
2( 1 2 4 5 8 ) ( 1 2 4 5 8 )( 1 2 4 5 8 ) ( 1 2 4 5 8 )Now, the
array is already sorted, but our algorithm does not know if it is
completed. The algorithm needs one whole pass without any swap to
know it is sorted.Third Pass:( 1 2 4 5 8 ) ( 1 2 4 5 8 )( 1 2 4 5 8
) ( 1 2 4 5 8 )( 1 2 4 5 8 ) ( 1 2 4 5 8 )( 1 2 4 5 8 ) ( 1 2 4 5 8
)Finally, the array is sorted, and the algorithm can terminate.
Analogue types of Computer uses what is known as analogue
signals that are represented by a continuous set of varying
voltages and are used in scientific research centers?, hospitals
and flight centersWith analogue types of computer no values are
represented by physical measurable quantities e.g. voltages.
Analogue computer types program arithmetic and logical operations
by measuring physical changes i.e. temperatures or pressure.
Digital Computer typeWith these types of computers operation are
on electrical input that can attain two inputs, states of ON=1 and
state of OFF = 0. With digital type of computers data is
represented by digital of 0 and 1 or off state and on state.
Digital computer type recognizes data by counting discrete signal
of (0 0r 1), they are high speed programmable; they compute values
and stores results. After looking at the Digital computer type and
how it functions will move to the third computer type as mentioned
above.
Hybrid type of ComputerHybrid computer types are very unique, in
the sense that they combined both analogue and digital features and
operations. With Hybrid computers operate by using digital to
analogue convertor and analogue to digital convertor. By linking
the two types of computer above you come up with this new computer
type called Hybrid.
***Got here on the first day of class.
