[COMPUTING]. PRONTUARIO-PIRRO, mechanical calculator. A remarkable Italian Prontuario-Pirro mechanical calculator, the ebonised cabinet casing surmounted by a stepped cornice with foliate carved pediment applied with the brass maker's plaque inscribed PRONTUARIO "Pirro" on an angled plinth base, the face with lacquered-brass vertical dial engraved 1-900,000 in divisions, with corresponding sliding bars each similarly engraved and with colored ivory "pawn"-shaped knobs in two sizes, colored red, white, cream, rose-pink, purple and black, each in a series of 9 bars, to one side an engraved scale 180-1 inscribed Gioti with sliding pointer, at the lower end of the scale an ivory scale inscribed in two parts with divisions for Provvigioni and Interessi. A handle at the side actuates by geared motion a roll of scales colored red and black, each scale value being viewed through a rectangular window drawn in ink 1 1 1 1 2 2 2 -2 -3 184-0, with roller-blind geared operation, the vertical cursor operating in unison with the roller-blind scales, with folding table easel support. (560mm high.)