Tebur na ASCII

Tebur ɗin ASCII: yadda lambobi 128 suka zama tushen rubutu

ASCII, gajarcewar American Standard Code for Information Interchange, shine tsarin lambobin da ya koya wa kwamfutoci su yarda a kan me ake nufi da harafi. An buga shi a 1963 kuma an inganta shi a cikin shekarun 1960, yana danganta kowane muhimmin harafi na rubutun Ingilishi, lambobi, da wasu alamomin sarrafawa zuwa lambobi wanda na’ura za ta iya ajiyewa da watsawa. Idan ka danna maballin baƙon A, kwamfutarka baya ajiye siffa, tana ajiye lamba 65. ASCII shine teburin bincike wanda ke sa wannan lamba ta zama A ko’ina ta tafi.

Ma’aunin ya shahara da ƙanƙantarsa. ASCII lamba ce ta bit 7, wanda ke nufin kowane harafi yana dacewa a cikin lambobin binary bakwai kuma dukkan jerin yana bazuwa daidai da 2 mai ƙarfin 7, ko lambobi 128 daban-daban wanda aka lambanta daga 0 zuwa 127. Wannan tanadi da gangan aka yi shi. Teletypes da modem na farko sun kasance suna jinkiri kuma masu tsada, don haka kowane bit yana da muhimmanci. Bit bakwai sun isa su ɗauko manyan da ƙananan haruffan Latin, lambobi goma, alamomin rubutu na kowa, da haruffan siginar da ke kiyaye na’urori a daidaitawa, tare da bit ɗaya da ya rage wanda tsarurruka da yawa ke amfani da shi domin duba kuskure.

Rabi biyu: haruffan sarrafawa da haruffan bugawa

Teburin yana rabuwa a fili zuwa yankuna biyu. Lambobin 0 zuwa 31, tare da lamba 127 (DEL), su ne haruffan sarrafawa. Waɗannan ba sa buga wata alama a allo. Maimakon haka suna umurtar na’ura ta yi wani abu: lamba 9 ita ce tab a kwance, lamba 10 ita ce line feed wanda ke ƙaura zuwa sabuwar layi, lamba 13 ita ce carriage return, kuma lamba 7 ita ce ƙararrawar da ta taɓa sa tashar tayi ƙara mai ji. Talatin da uku ne daga cikin waɗannan lambobin siginar da suke wanzuwa gaba ɗaya, kuma ko da yake yawancinsu abubuwa ne na tarihi yanzu, line feed, carriage return, da tab suna wanzuwa a matsayin muhimmi ga yadda ake tsara fayilolin rubutu a yau.

Lambobin 32 zuwa 126 su ne haruffan bugawa, casa’in da biyar duka. Lamba 32 ita ce sarari, wanda ke ƙidaya a matsayin mai bugawa domin yana ci gaba da mai nuni ko da yake ba ya nuna komai. Daga can za ka sami alamomin rubutu da alamomi, lambobi 0 zuwa 9 a lambobi 48 zuwa 57, manyan haruffa A zuwa Z a 65 zuwa 90, da ƙananan haruffa a zuwa z a 97 zuwa 122. Wani fasali mai kyau yana fitowa daga wannan tsari: siffar ƙarama da babba na harafi ɗaya suna bambanta da daidai 32, shi ya sa juya bit ɗaya kawai ke canja babba/ƙarama. Waɗannan tsare-tsaren ba haɗari ba ne, an tsara su ne domin jerawa da canjin babba/ƙarama za a iya yin su da lissafin ilmin lissafi mai sauƙi.

Decimal, hexadecimal, da binary: hangowa uku na lamba ɗaya

Kowace lambar ASCII lamba ce kawai, kuma za ka gan ta a rubuce ta hanyoyi uku. Decimal itace tsarin base-10 na yau da kullum, don haka A shine 65. Hexadecimal, base 16, shine tsarin da masu shirya lambobin kwamfuta ke amfani da shi domin yana daidaita da bytes: A shine 0x41, kuma yankin bugawa yana gudana daga 0x20 zuwa 0x7E. Binary, base 2, shine tsarin da hardware take ainihin ajiyewa, don haka A shine 1000001 a cikin bit ɗinta bakwai. Harafi ɗaya, salo uku, da sanin yadda ake motsawa tsakaninsu wata fasaha ce mai muhimmanci idan kana karanta bayanan memory ko zirga-zirgar hanyar sadarwa. Idan kana aiki da waɗannan juyawa akai-akai, faɗaɗɗen jerin tebur ɗin bayanai a speedor.net yana ajiye danganta a danna guda kawai.

Inda ASCII har yanzu take da muhimmanci

Zai zama kuskure a jera ASCII a ƙarƙashin tarihi. Tana raye a cikin aikin yau da kullum na duk wanda ya taɓa lambar kwamfuta. Harsunan shirye-shirye suna ɗaukar string literals, fayilolin tushe, da kalmomin ka’idar sadarwa a matsayin ASCII a matakin byte. Ka’idojin sadarwa irin su sashin HTTP, SMTP, da tsare-tsare masu yawa na daidaitawa an ƙayyade su a ASCII domin su ci gaba da karantuwa ga mutane. Idan string ya bayyana ya lalace, masu shirya lambobi suna kama mai kallon hex kuma su karanta ainihin bytes ɗin bisa teburin ASCII domin gano wani harafin sarrafawa da ya kauce ko kuskuren ƙarshen layi. URL encoding, Base64, da escape sequences duk suna gina bisa ƙimomin ASCII. Ga duk wanda ke gyara kwarraran encoding, wani ɗan bayanan bincike kusa da kayan aikin masu shirya lambobi namu yana mayar da wani byte mai ɓoye zuwa amsa a bayyane.

Daga ASCII zuwa Unicode da UTF-8

ASCII ta sarrafa Ingilishi da kyau amma kusan babu wani harshe. Iyakar haruffa 128 ba za ta iya ɗaukar haruffa masu lamba, Cyrillic, Sinanci, Larabci, ko emoji ba. Unicode ta amsa wannan ta hanyar bayar da lamba ta musamman, wanda ake kira code point, ga kowane harafi a cikin kowane tsarin rubutu, yanzu sun wuce dubu ɗari da yawa. Abin da ya fi muhimmanci, Unicode kundin haruffa ne, ba tsarin ajiya ba, don haka tana bukatar encoding domin ta juya waɗannan code points zuwa bytes.

UTF-8 ita ce wannan encoding, kuma ita ce sanadin da ASCII bata taɓa ɓacewa da gaske ba. UTF-8 tana amfani da byte ɗaya zuwa huɗu ga kowane harafi, kuma an tsara ta ne domin code points 0 zuwa 127, dukkan yankin ASCII, an ajiye su a byte ɗaya wanda daidai yake da ASCII na yau da kullum. Wannan yana sa UTF-8 ta zama mai daidaitawa da baya sosai: duk wani fayil na ASCII mai kyau riga fayil ne na UTF-8 mai kyau. Haruffan da suka wuce 127 suna amfani da ƙarin bytes. Wannan daidaitawar mai kyau babban sanadi ne da UTF-8 take zamowa mafi yawan yanar gizo yanzu. A taƙaice, ASCII shine ainihin tushen haruffa 128, Unicode shine kundin duniya wanda ke ɗauke da ita, kuma UTF-8 shine encoding wanda ke ɗauke da su biyun yayin da ke ajiye rubutun ASCII ba tare da canji ba byte-da-byte.

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