Umgangatho we-ASCII wamkelwa ngo-1963, kwaye ngoku akukho mntu usebenzisa i-encoding oonobumba bokuqala be-128 bahluke kwi-ASCII. Nangona kunjalo, kude kube sekupheleni kwenkulungwane edlulileyo, i-EBCDIC yayisetyenziswa ngenkuthalo-umgangatho wokufakwa kwekhowudi kwii-IBM eziphambili kunye neekhompyuter zabo zeSoviet ze-EC. I-EBCDIC ihlala iyikhowudi ephambili kwi-z/OS, isistim esisebenzayo se-IBM Z eziphambili zale mihla.
Yintoni ngokukhawuleza ibambe iliso lakho xa ujonga i-EBCDIC kukuba iileta azikho ngokulandelelana: phakathi I и J naphakathi R и S bekukho iindawo ezingasetyenziswanga (kwikhompyuter ye-ES kula maxesha Abalinganiswa besiCyrillic). Ngubani owayenokucinga ukubethelela oonobumba abanezithuba ezingalinganiyo phakathi koonobumba abakufutshane?
Kwa igama elithi EBCDIC (“I-BCDIC eyandisiweyo”) libonisa ukuba olu khowudo - ngokungafaniyo ne-ASCII - aluzange lwenziwe kwasekuqaleni, kodwa lusekwe kwi-encoding ye-BCDIC ene-bits ezintandathu, eye yasetyenziswa ukususela ngoko. (1954):
Akukho ukuhambelana kwangoko ngasemva: into efanelekileyo ye-BCDIC eyalahleka kutshintsho lwe-EBCDIC yayikukuba amanani 0-9 zihambelana neekhowudi 0-9. Nangona kunjalo, kukho izithuba zeekhowudi ezisixhenxe phakathi I и J kunye neekhowudi ezisibhozo phakathi R и S sele ndifikile kwi-BCDIC. Zivela phi?
Imbali ye (E)BCDIC iqala ngaxeshanye kunye nembali ye-IBM - kwakudala phambi kweekhompyuter ze-elektroniki. I-IBM iye yasekwa ngenxa yokudityaniswa kweenkampani ezine, apho ezona teknoloji yayiyiNkampani yeTabulating Machine, eyasekwa ngo-1896 nguHerman Hollerith, umqambi. . Iithayibhuli zokuqala zibala nje inani lamakhadi abethelelwe kwindawo ethile; kodwa ngowe-1905 uHollerith waqalisa ukuvelisa idesimali iithayibhulari. Ikhadi ngalinye lethabhulatha yedesimali liquka iindawo ezinobude obungenasizathu, kwaye amanani abhalwe kule mihlaba ngokwesiqhelo sedesimali aye ashwankathelwa kumgangatho wonke. Ukwahlulwa kwemephu kwiindawo kumiselwe ngokuqhagamshela iingcingo kwipatch panel ye-tabulator. Umzekelo, kweli khadi likaHollerith, kwiThala leeNcwadi leCongress, inombolo 23456789012345678 isitampu ngokucacileyo, ayaziwa njengoko yahlulwe ngokwemihlaba:
Oyena mntu unomdla unokuqaphela ukuba kwimephu yaseHollerith kukho imiqolo eyi-12 yemingxuma, nangona ishumi lanele kumanani; kwaye kwi-BCDIC, ngexabiso ngalinye lezona zinto zibalulekileyo ezimbini, kuphela iikhowudi ezili-12 ezisetyenziswayo kwi-16 enokwenzeka.
Kakade ke, oku akuyonto nje yazenzekela. Ekuqaleni, uHollerith wayefuna imiqolo eyongezelelweyo "yamanqaku akhethekileyo" angazange adityaniswe, kodwa abalwe ngokulula - njengakwitabulayitha zokuqala. (Namhlanje siza kubabiza ngokuthi "bit fields".) Ukongezelela, phakathi "kwamanqaku akhethekileyo" kwakunokwenzeka ukuseta izikhombisi zeqela: ukuba i-tabulation ayifuni kuphela iimali zokugqibela, kodwa kunye neziphakathi, ngoko i-tabulator iya kumisa ibone utshintsho kuzo naziphi na izikhombisi zeqela , kwaye umqhubi kufuneka aphinde abhale iitotali ezisezantsi kwiibhodi zedijithali ephepheni, usethe kwakhona ibhodi, kwaye aqalise ukucwangciswa kwakhona. Umzekelo, xa ubala iibhalansi zokubala, iqela lamakhadi lingangqamana nomhla omnye okanye iqabane elinye.
Ngowe-1920, xa uHollerith wayesele edla umhlala-phantsi, kwasetyenziswa “iimatshini zokuchwetheza” ezaziqhagamshelwe kumatshini wokubhala yaye zazikwazi ukuprinta iitotali ezingaphantsi ngokwazo ngaphandle kokufuna ukungenelela kwabasebenzisi. Ubunzima ngoku yayikukufumanisa ukuba inani ngalinye kula ashicilelweyo libhekiswa kulo. Ngomnyaka we-1931, i-IBM yagqiba ekubeni isebenzise "amanqaku akhethekileyo" ukubonisa oonobumba: uphawu kumqolo we-12 lubonise ileta evela. A до I, kwi-11 - ukusuka J до R, kwiqanda - ukusuka S до Z. I-"alphabet tabulator" entsha inokushicilela igama leqela ngalinye lamakhadi kunye neetotali ezincinci; kulo mzekelo, ikholamu engaqhawukanga yajika yaba sisithuba phakathi kweempawu. Nceda uqaphele ukuba S ityunjwe yindibaniselwano yomngxuma 0+2, kwaye udibaniso lwe-0+1 aluzange lusetyenziswe ekuqaleni ngenxa yokoyika ukuba imingxuma emibini ecaleni komnye kuluhlu olufanayo lunokubangela iingxaki zoomatshini kumfundi.
Ngoku ungajonga itafile ye-BCDIC kwi-engile eyahlukileyo kancinci:
Ngaphandle kokuba i-0 kunye nesithuba zibuyiselwe umva, awona masuntswana amabini abaluleke kakhulu achaza "uphawu olulodwa" olubethelelwe kwikhadi lepunch lomlinganiswa ohambelanayo ukusukela ngo-1931; kwaye amasuntswana amane abalulekileyo amisela idijithi efakwe kwindawo ephambili yekhadi. Inkxaso yophawu & - / yongezwa kwii-tabulators ze-IBM kwiminyaka yee-1930, kwaye i-encoding ye-BCDIC yabalinganiswa ihambelana nendibaniselwano yomngxuma ebethelelwe yona. Xa ukuxhasa inani elikhulu loonobumba kwakufuneka, umqolo wesi-8 wabethelwa “njengophawu olukhethekileyo” olongezelelweyo - ngoko ke, kwakunokubakho imingxunya emithathu kwikholamu enye. Le fomati yamakhadi athotyiweyo yahlala ingatshintshi de kwasekupheleni kwenkulungwane. Kwi-USSR, bashiya i-IBM yesiLatini kunye neekhowudi zokubhala, kwaye kwiileta zesiCyrillic babetha "amanqaku akhethekileyo" amaninzi kanye kwimiqolo ye-12, 11, 0 - ingaphelelanga kwimingxuma emithathu kwikholamu enye.
Xa ikhompyuter ye-IBM 704 yenziwa, abazange bacinge ixesha elide malunga ne-encoding yomlingiswa wayo: bathatha i-encoding esele isetyenziswe kumakhadi atyunjiweyo ngelo xesha, kwaye "bayibeka endaweni yayo." Kwi-0, ngexesha lokutshintsha ukusuka kwi-BCDIC ukuya kwi-EBCDIC, i-low-order four bits yesimboli ngasinye ishiywe ingatshintshi, nangona i-high-order bits yaxutywa kancinane. Ke, ifomathi yekhadi echongiweyo ekhethwe nguHollerith ekuqaleni kwenkulungwane edlulileyo ibe nefuthe kuyilo lwazo zonke iikhompyuter ze-IBM, ukuya kuthi ga kwi-IBM Z.
umthombo: www.habr.com