求英语翻译不要机器翻译的1.Programminginmachinelanguagesmeansspeakingdirectlytothecomputerinthelanguageof1sand0situnderstands.Machinelanguageisthefastestbecausenotranslationisrequiredonthecomputer’spart.
求英语翻译不要机器翻译的
1.Programminginmachinelanguagesmeansspeakingdirectlytothecomputerinthelanguageof1sand0situnderstands.Machinelanguageisthefastestbecausenotranslationisrequiredonthecomputer’spart.However,itisalmostimpossibletolearn-imaginehavingtoenterastring(字符串)ofhundredsofbinarydigitsjusttotellthecomputertoperformabasicoperationlikeaddingnumbers.Nevertheless,thisishowthefirstgeneration(代)computerswereprogrammed.
2.Operatingsystemshavedevelopedoverthepastthirtyyearsfortwomainpurposes.First,theyprovideaconvenientenvironmentforthedevelopmentandexecutionofprograms.Second,operatingsystemsattempttoschedulecomputationalactivitiestoensuregoodperformanceofthecomputingsystem.Theoperatingsystemmustensurecorrectoperationofthecomputersystem.Topreventuserprogramsfrominterferingwiththeproperoperationofthesystem,thehardwarewasmodifiedtocreatetwomodes:usermodeandmonitormode.
3.Theinput/outputandsecondary(辅助)storageunitsaresometimescalledperipheraldevices(orjustperipherals).ThisterminologyreferstothefactthatalthoughthesedevicesarenotapartoftheCPU,theyareoftenlocatednearit.Besides,acomputersystemalsoincludesbuses,ROM(readonlymemory),RAM(randomaccessmemory),parallel(并行)portandserial(串行)port,harddisk,floppiesandCD(computerdisk)drive,andsoon.
4.OutputDevicesLikeinputunits,outputdevicesareinstrumentsofinterpretationandcommunicationbetweenhumansandcomputersystemsofallsizes.ThesedevicestakeoutputresultsfromtheCPUinmachine-codedformandconvertthemintoaformthatcanbeused(a)bypeople(e.g.,aprintedand/ordisplayedreport)or(b)asmachineinputinanotherprocessingcycle.
5.Theoperatingsystemmustensurecorrectoperationofthecomputersystem.Topreventuserprogramsfrominterferingwiththeproperoperationofthesystem,thehardwarewasmodifiedtocreatetwomodes:usermodeandmonitormode.Variousinstructions(suchasI/Oinstructionsandhaltinstructions)areprivilegedandcanonlybeexecutedinmonitormode.Thememoryinwhichthemonitorresidesmustalsobeprotectedfrommodificationbytheuser.Atimerprev