- enabled , ▁but ▁the ▁effective ▁result ▁was ▁a ▁dual ▁version - number ing ▁scheme . ▁ ▁Version ▁history ▁ ▁Vers ions ▁ 1 . 0 ▁( 1 9 8 2 ) ▁First ▁release ▁for ▁H P ▁ 9 0 0 0 ▁Series ▁ 5 0 0 . ▁H P - U X ▁for ▁Series ▁ 5 0 0 ▁was ▁substantial ly ▁different ▁than ▁H P - U X ▁for ▁any ▁other ▁H P ▁machines , ▁as ▁it ▁was ▁layer ed ▁at op ▁a ▁Series ▁ 5 0 0 ▁specific ▁operating ▁system ▁called ▁S UN OS ▁( un related ▁to ▁the ▁Sun ▁Mic ros ystem s ▁Sun OS ). ▁ 1 . 0 ▁( 1 9 8 4 ) ▁AT & T ▁System ▁III ▁based . ▁Support ▁for ▁the ▁H P ▁Integr al ▁PC ▁( HP ▁ 9 8 0 7 A ). ▁The ▁kernel ▁runs ▁from ▁R OM ; ▁other ▁commands ▁are ▁disk ▁based . ▁ 2 . 0 ▁( 1 9 8 4 ) ▁First ▁release ▁for ▁H P ' s ▁early ▁Motor ola ▁ 6 8 0 0 0 - based ▁work st ations ▁( HP ▁ 9 8 1 6 U , ▁H P ▁ 9 8 2 6 U , ▁H P ▁ 9 8 3 6 U ) ▁ 5 . 0 ▁( 1 9 8 5 ) ▁R OM - based ▁AT & T ▁System ▁V ▁for ▁the ▁H P ▁Integr al ▁PC . ▁Dist inct ▁from ▁a ▁later ▁H P - U X ▁ 5