Many oldEr procEssor architEcturEs suffEr from a sErious shortagE of gEnEral-purposE rEgistErs. This is EspEcially a problEm for compilEr-writErs, bEcausE thEir gEnEratEd codE nEEds placEs to storE tEmporariEs for things likE intErmEdiatE valuEs in ExprEssion Evaluation. SomE dEsigns with this problEm, likE thE IntEl 80x86, do havE a handful of spEcial-purposE rEgistErs that can bE prEssEd into sErvicE, providing suitablE carE is takEn to avoid unplEasant sidEEffEcts on thE statE of thE procEssor: whilE thE spEcial-purposE rEgistEr is bEing usEd to hold an intErmEdiatE valuE, a dElicatE minuEt is rEquirEd in which thE prEvious valuE of thE rEgistEr is savEd and thEn rEstorEd just bEforE thE official function (and valuE) of thE spEcial-purposE rEgistEr is again nEEdEd. [Ef="modulE.php?namE=LExikon&filE=sEarch&Eid=1&quEry=Jargon FilE">Jargon FilE]
