Ib tug ntxiv xim coding yog ib tug tshiab version launched los ntawm NEC nyob rau hauv 1937, uas siv cov xim-coded kab nrog" multi-cranch circuits" thiab qhia tau hais tias cov kab ntawm peb ceg circuits yuav tsum yog dub, liab, thiab dawb. Ntau ceg tuaj yeem ntxiv lwm cov xim, xws li daj thiab xiav.
Xyoo 1953, NEC tau hloov xim av xaim mus rau ntsuab lossis liab qab. Ntsuab kuj raug txwv rau cov kab hluav taws xob (xws li cov kab nyob thiab nruab nrab).
Lub 1971 version ntawm NEC muab cov xim ntau cov kab lis kev cai los khiav. Txawm hais tias cov kab dawb, ntuj grey, ntsuab, thiab daj-ntsuab kab txaij tseem khaws cia, cov xim no tseem txwv tsis pub siv rau cov kab hauv av. Lub sijhawm no cov lus qhia tau poob qis cov xim coding uas yuav tsum tau ua rau cov xov hlau nkag, vim tias tsis muaj xim txaus kom paub qhov txawv ntawm cov tshuab, voltages thiab circuits.
