Abstract: A substantially thin keyboard for use in credit card sized clock calculators or the like includes a rigid plate carrying a plurality of stationary key contacts, a flexible member integral with a plurality of electrically conductive rubber movable contacts and a keyboard surface member, all of which are stacked in the named order. An indicia sheet is interposed between the flexible member and the keyboard surface member, which carries a plurality of groups of key indicia or markings. A slide switch is movably attached so as to shift the key indicia carried on the sheet in relation to the plurality of the stationary key contacts group by group. Masking members are secured on part of the keyboard surface member to conceal all the groups of the key indicia from view other than one group of the key indicia is presented in register with the stationary key contacts.

Abstract: A solar battery panel is installed on an electronic calculator through an arrangement formed on a rear casing of the electronic calculator or on a glass substrate supporting a display unit, a semiconductor chip, and wiring leads. The solar battery panel is exposed to light through a window formed on the rear casing or a rear casing over the glass substrate. A wallet is provided for protecting and supporting the electronic calculator. The solar battery panel is exposed to the outside through a window in the wallet even when the wallet is surrounding the electronic calculator.