Katin naushi, wanda kuma aka sani da kati mai naushi, takarda ce mai kauri ko siraren kwali wanda ke dauke da bayanan dijital wanda jerin ramukan da aka buga a wasu wurare. An saba amfani da katunan Punch azaman hanyar adana bayanai a farkon ƙididdigewa da tsarin sarrafa bayanai, musamman daga shekarun 1890 zuwa tsakiyar 1970s. An yi amfani da su don ayyuka kamar shigar da bayanai, sarrafawa, da fitarwa, da kuma sarrafa injina masu sarrafa kansa. Kalmar "katin buɗa" kuma tana nufin tsarin ƙirƙira ko buga ramuka a cikin katin don wakiltar bayanan dijital.