▁train ▁room ▁describes ▁two ▁buttons ▁by ▁the ▁door ▁l abeled ▁" foo " ▁and ▁" bar ". ▁These ▁were ▁general ▁purpose ▁buttons ▁and ▁were ▁often ▁re - pur posed ▁for ▁whatever ▁fun ▁idea ▁the ▁M IT ▁hack ers ▁had ▁at ▁the ▁time , ▁hence ▁the ▁ad option ▁of ▁foo ▁and ▁bar ▁as ▁general ▁purpose ▁variable ▁names . ▁An ▁entry ▁in ▁the ▁A brid ged ▁Dictionary ▁of ▁the ▁T M RC ▁Language ▁states : ▁ ▁The ▁shift ▁from ▁the ▁military ▁expression ▁F UB AR ▁to ▁fo obar ▁may ▁also ▁have ▁been ▁driven ▁by ▁the ▁latter ▁being ▁a ▁computer ▁science ▁pun . ▁ ▁Since ▁over bars ▁design ate ▁repeating ▁decimal ▁numbers , ▁the ▁word ▁fo obar ▁also ▁sign ifies ▁a ▁number ▁in ▁hex ade c imal , ▁a ▁base ▁typically ▁used ▁in ▁low ▁level ▁programming . ▁ ▁That ▁number ▁is ▁ 0 . F 0 0 F 0 0 F 0 0 ▁... ▁, ▁which ▁equals ▁the ▁decimal ▁fraction ▁ 2 5 6 / 2 7 3 . ▁ ▁The ▁term ▁fo obar ▁was ▁propag ated ▁through ▁computer ▁science ▁circles ▁in ▁the ▁ 1 9 6 0 s ▁and ▁early ▁ 1 9 7 0 s ▁by ▁system ▁manual s ▁from ▁Digital ▁Equ ip ment ▁Corporation . ▁Fo obar ▁was ▁also ▁used ▁as ▁a ▁variable ▁name ▁in ▁the ▁Fort ran ▁code ▁of ▁Col oss al ▁C ave ▁Advent ure ▁( 1 9 7 7 ▁Crow ther ▁and ▁Wood s ▁version ). ▁The ▁variable ▁FO OB AR ▁was ▁used ▁to ▁contain ▁the ▁player ' s ▁progress