Serial chaw nres nkoj thiab nws qhov tseeb

Tam sim no hnov cov lus "ports rau lub computer", koj tsis tas yuav mus rau tshwj xeeb khw muag khoom noj, los yog yuav tus tswv ntawm lub computer technology. Tom qab tag nrho, txawm lub tsev kawm ntawv cov menyuam kawm ntawv zoo versed nyob rau hauv cov teeb meem no.

Thaum cov lus "chaw nres nkoj" ib tug txiv neej feem ntau yog sawv cev berth nrog siab cranes nyob qhov twg lub loj ships nkag mus, xa khoom thiab chaw thau khoom ntawm cov khoom. Nyob rau hauv computer engineering tswv yim tso zis chaw nres nkoj yog ib tug ntawm cov ntau ntau yam ntawm kho vajtse interface tsim los txuas cov sab hauv thiab peripheral pab kiag li lawm mus rau ib tug motherboard bus cov ntaub ntawv. Txij li thaum lub tsos ntawm cov thawj computers tau npaj ib tug loj tus naj npawb ntawm ntau ports uas txawv ob lub cev yuav siv thiab cov txheej txheem siv. Ib txhia tau dim thiab siv txawm niaj hnub no. Piv txwv li, ib tug serial chaw nres nkoj, ntau motherboard manufacturers tau dua unsoldering rau lawv cov khoom.

Yuav ua li cas yog nws thiaj li zoo kawg li? Asynchronous serial chaw nres nkoj (tej thaum hu COM, los ntawm cov lus Askiv. Lo lus «Communications») nyob rau hauv lub thawj IBM-tshaj computer qauv. Siv mus cuag nas, modem thiab lwm yam peripheral pab kiag li lawm, thiab lub koom haum (yuav tsum tau thov-modem cable), yooj yim network kev twb kev txuas ntawm ob computers. Ib tug ntawm qhov zoo muaj los ntawm lub serial chaw nres nkoj yog nyob rau hauv lub simplicity ntawm cov kev kho vajtse thiab software siv.

Lub cev, nws yog sawv cev los ntawm 9 los yog 25-pin connector. Cov ntaub ntawv kis tau tus mob yuav siv sij hawm qhov chaw nyob rau hauv nws me ntsis los ntawm me ntsis, successively (incidentally, lub thib ob chaw pib lub npe). Raws tu qauv yog tsis raug mus rau txhua lub sij hawm txwv mus rau lub caij nyoog nruab nrab txhua txhua 16 khoom (2 bytes). Tsaug rau no feature, lub serial chaw nres nkoj yog tej zaum hu ua asynchronous.

Nws yuav tsum tau muab sau tseg hais tias lub ntsis nqi ntaub ntawv yog tseem tswj. Yog li, nyob rau hauv ib tug txheej txheem kho vajtse siv, cov kev tso cai tus nqi 115.200 khoom ib ob (bps), txawm hais tias feem ntau lub qhov rais kev khiav hauj lwm systems nws yog artificially tas rau 9600 (rau cov neeg siv yuav ua kev kho me ntsis rau cov ntaus thawj). Tsis zoo li lwm yam serial interfaces (USB, FireWire) khoom yog sau rau hauv ntawv, thiab kis tau rau hauv feem.

Ib tug ntau USB interface tau siv nrog rau cov aim ntawm ousting los ntawm kev ua lag luam ntawm kev laus COM chaw nres nkoj (REYE-232C). Qhov no kauj ruam yog inevitable, txij thaum lub cov ntaub ntawv hloov lwm lub tsev ceev nyob rau hauv lub feem ntau tsim ntau yam tsuas yog 921.600 baud, uas yog tsis txaus (piv rau USB thiab 480 Mb / s). Qhov thib ob drawback - nws yog tsis yooj yim sua rau "kub" kev twb kev txuas: ib qho los mus txuas rau lub ntaus ntawv mus rau lub serial chaw nres nkoj thaum lub computer yog ciav tau nyob rau hauv qhov zoo tshaj plaws cov ntaub ntawv rau lub cev tsis ua hauj lwm vim tsis muaj Plug & Ua si technology, thiab rau ntawm phem tshaj - mus rau lub tsis ua hauj lwm ntawm ob leeg lub ntaus ntawv thiab cov maub los COM chaw nres nkoj nyob hauv lub motherboard (expansion card).

Vim hais tias ntawm no, ib tug li ob peb xyoos dhau los, tag nrho cov muab phaib tsis muaj lub COM chaw nres nkoj, raws li tau tshwm sim nrog PS / 2 thiab AGP. Txawm li cas los, ib tug loj tus naj npawb ntawm uas twb muaj lawm peripherals tsim los ua hauj lwm nrog ib tug serial chaw nres nkoj, yuam manufacturers tsam lub cav muab lub COM thiab txawm LPT (thaum uas tig mus). Tsis doubt, ntau cov neeg siv tau hais rau lawv "ua tsaug". Tom qab flashing rau ib tug satellite receiver yog tam sim no tsis muaj yuav tsum tau mus nrhiav ib tug laus computer los yog yuav tsis adapters, inverters. Tsis tas li ntawd, feem ntau cov kuj ua hauj lwm los ntawm lub serial chaw nres nkoj, raws li cov kev sau ntawv tswj cov kev pab cuam tsis ua teeb meem ntau heev rau nws.

Nws yog nthuav tias muaj ntau ntawm niaj hnub no peripherals mus ua hauj lwm nyob rau hauv lub operating system emulates ib COM chaw nres nkoj. Qhov no cov xov tooj txawb, radios, lub Bluetooth adapter , thiab lwm tus neeg. Ntawm cov hoob kawm, tus yam ntxwv ntawm lub virtual chaw nres nkoj yog ntau tshaj li tus qauv siv.