CDP1871A Datasheet | Intersil

CDP1871A, CDP1871AC REFERENCE APP NOTE 7374 August 1996 CMOS Keyboard Encoder Description The CDP1871A is a keyboard encoder designed to directly interface between a CDP1800-series microprocessor and a mechanical keyboard array, providing up to 53 ASCII coded keys and 32 HEX coded keys, as shown in the system diagram (Figure 1). The keyboard may consist of simple single-pole single-throw (SPST) mechanical switches. Inputs are provided for alpha-lock, control, and shift functions, allowing 160 unique codes. An external R-C input is available for user-selectable debounce times. The Nkey lock-out feature prevents unwanted key codes if two or more keys are pressed simultaneously. The CDP1871A...