COA UNIT-1 Input-Output Instructions.pdf

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It looks like you’re asking for a detailed explanation or expansion of the previous information into a 3000-word format. While I can provide a thorough and detailed response, generating exactly 3000 words might be a bit challenging in this format. However, I can certainly give you a comprehensive overview and expand on the topic significantly. Here’s a more detailed explanation:

Understanding Input and Output Instructions
When we talk about input and output instructions, we are generally referring to the process of providing data to a system (input) and receiving results from it (output). This concept is fundamental in various fields, including computing, electronics, and even everyday tasks. Let’s break down the key aspects of input and output instructions.

1. Definition and Importance
Input refers to the data or signals that are fed into a system for processing. This can be anything from user commands, sensor readings, or data from other systems. Output, on the other hand, is the result produced by the system after processing the input. This could be in the form of visual displays, printed documents, sound, or even actions performed by a machine.

The importance of input and output instructions lies in their ability to facilitate interaction between the user and the system. Without proper input, a system cannot function correctly, and without output, the user cannot understand or utilize the results of the system’s processing.

2. Types of Input and Output
There are various types of input and output, depending on the context:

In Computing:
Input Devices: Keyboards, mice, scanners, microphones.
Output Devices: Monitors, printers, speakers.
In Electronics:
Input Signals: Voltage, current, digital signals.
Output Signals: Processed signals, control signals.
In Everyday Life:
Input: Instructions given to a person or machine.
Output: Actions performed or results produced.
3. Examples in Different Contexts
Computing:
When you type on a keyboard (input), the characters appear on the screen (output).
Clicking a mouse button (input) can open a file or application (output).
Electronics:
A temperature sensor (input) sends data to a thermostat, which then adjusts the heating system (output).
Daily Activities:
Giving a recipe to a cook (input) results in a prepared dish (output).
4. Detailed Process
The process of input and output can be broken down into several steps:

Receiving Input:
The system receives data or commands from an input device or source.
This data is often converted into a format that the system can understand.
Processing Input:
The system processes the input data according to predefined instructions or algorithms.
This may involve calculations, data manipulation, or decision-making processes.
Generating Output:
The processed data is converted into a format suitable for output.
The system sends the output to the appropriate device or medium.
Delivering Output:
The output is delivered to the user or another system.
This

1. Input-OutputandInterrupt
•Acomputercanservenousefulpurposeunless
itcommunicateswiththeexternalenvironment.
•Instructionsanddatastoredinmemorymust
comefromsomeinputdevice.
•Computationalresultsmustbetransmittedto
theuserthroughsomeoutputdevice.
•Todemonstratethemostbasicrequirementsfor
inputandoutputcommunication,wewilluseas
anillustrationaterminalunitwithakeyboard
andprinter.

2. Input-OutputConfiguration
•Theterminalsendsandreceivesserial
information.
•Eachquantityofinformationhaseightbitsof
analphanumericcode.
•Theserialinformationfromthekeyboardis
shiftedintotheinputregisterINPR.
•Theserialinformationfortheprinteris
storedintheoutputregisterOUTR.
•Thesetworegisterscommunicatewitha
communicationinterfaceseriallyandwith
theACinparallel.

4. •The1-bitinputflagFGIisacontrolflip-flop.The
flagbitissetto1whennewinformationis
availableintheinputdeviceandisclearedto0
whentheinformationisacceptedbythe
computer.
•Theflagisneededtosynchronizethetiming
ratedifferencebetweentheinputdeviceand
thecomputer.
•Theprocessofinformationtransferisasfollows.
Initially,theinputflagFGIisclearedto0.When
akeyisstruckinthekeyboard,an8-bit
alphanumericcodeisshiftedintoINPRandthe
inputflagFGIissetto1.

5. •Aslongastheflagisset,theinformationinINPRcannotbe
changedbystrikinganotherkey.
•Thecomputercheckstheflagbit;ifitis1,theinformation
fromINPRistransferredinparallelintoACandFGIiscleared
to0.
•Oncetheflagiscleared,newinformationcanbeshiftedinto
INPRbystrikinganotherkey.
•TheoutputregisterOUTRworkssimilarlybutthedirection
ofinformationflowisreversed.Initially,theoutputflag
FGOissetto1.
•Thecomputercheckstheflagbit;ifitis1,theinformation
fromACistransferredinparalleltoOUTRandFGOiscleared
to0.
•Theoutputdeviceacceptsthecodedinformation,printsthe
correspondingcharacter,andwhentheoperationis
completed,itsetsFGOto1.
•ThecomputerdoesnotloadanewcharacterintoOUTR
whenFGOis0becausethisconditionindicatesthatthe
outputdeviceisintheprocessofprintingthecharacter.

6. Input-OutputInstructions
•Inputandoutputinstructionsareneededfor
transferringinformationtoandfromACregister,for
checkingtheflagbits,andforcontrollingthe
interruptfacility.
•Input-outputinstructionshaveanoperationcode
1111andarerecognizedbythecontrolwhenD7=1
andI=1.
•Theremainingbitsoftheinstructionspecifythe
particularoperation.
•Theseinstructionsareexecutedwiththeclock
transitionassociatedwithtimingsignalT3.
•EachcontrolfunctionneedsaBooleanrelationD7IT3,
whichwedesignateforconveniencebythesymbolp.
•Thecontrolfunctionisdistinguishedbyoneofthe
bitsinIR(6-11).

7. Input-Output Instructions

8. •TheINPinstructiontransferstheinputinformation
fromINPRintotheeightlow-orderbitsofACandalso
clearstheinputflagto0.
•TheOUTinstructiontransferstheeightleast
significantbitsofACintotheoutputregisterOUTR
andclearstheoutputflagto0.
•ThenexttwoinstructionsinTablecheckthestatusof
theflagsandcauseaskipofthenextinstructionifthe
flagis1.
•Theinstructionthatisskippedwillnormallybea
branchinstructiontoreturnandchecktheflagagain.
Thebranchinstructionisnotskippediftheflagis0.
•Iftheflagis1,thebranchinstructionisskippedand
aninputoroutputinstructionisexecuted.Thelast
twoinstructionssetandclearaninterruptenableflip-
flopIEN.

9. ProgramInterrupt
•Theprocessofcommunicationjustdescribedis
referredtoasprogrammedcontroltransfer.
•Thecomputerkeepscheckingtheflagbit,and
whenitfindsitset,itinitiatesaninformation
transfer.
•Thedifferenceofinformationflowratebetween
thecomputerandthatoftheinput-output
devicemakesthistypeoftransferinefficient.
•Thecomputeriswastingtimewhilechecking
theflaginsteadofdoingsomeotheruseful
processingtask.
•Analternativetotheprogrammedcontrolled
procedureistolettheexternaldeviceinform
thecomputerwhenitisreadyforthetransfer.

10. •whenaflagisset,thecomputerismomentarily
interruptedfromproceedingwiththecurrent
programandisinformedofthefactthataflaghas
beenset.
•Thecomputerdeviatesmomentarilyfromwhatitis
doingtotakecareoftheinputoroutputtransfer.It
thenreturnstothecurrentprogramtocontinuewhat
itwasdoingbeforetheinterrupt.
•Theinterruptenableflip-flopIENcanbesetand
clearedwithtwoinstructions.
•WhenIENisclearedto0(withtheIOFinstruction),
theflagscannotinterruptthecomputer.
•WhenIENissetto1(withtheIONinstruction),the
computercanbeinterrupted.
•Thesetwoinstructionsprovidetheprogrammerwith
thecapabilityofmakingadecisionastowhetheror
nottousetheinterruptfacility.

12. •Aninterruptflip-flopRisincludedinthecomputer.
WhenR=0,thecomputergoesthroughan
instructioncycle.
•DuringtheexecutephaseoftheinstructioncycleIEN
ischeckedbythecontrol.
•Ifitis0,itindicatesthattheprogrammerdoesnot
wanttousetheinterrupt,socontrolcontinueswith
thenextinstructioncycle.
•IfIENis1,controlcheckstheflagbits.Ifbothflags
are0,itindicatesthatneithertheinputnorthe
outputregistersarereadyfortransferofinformation.
•Inthiscase,controlcontinueswiththenext
instructioncycle.Ifeitherflagissetto1whileIEN=1,
flip-flopRissetto1.
•Attheendoftheexecutephase,controlchecksthe
valueofR,andifitisequaltol,itgoestoaninterrupt
cycleinsteadofaninstructioncycle.

13. Demonstration of Interrupt cycle