Key input system for electronic computer with crt display unit

Abstract

Abstract PURPOSE: To simplify the constitution of the key input control part and thus enhancing the economical property of the system, by producing the key code with the key operation signal sent from the key matrix circuit and the address designation signal sent from the CRT controller. CONSTITUTION: The data of 3 bits is converted into the timing pulses via decoder 17 among the address data of 8 bits which is delivered from CRT controllr CRTC14 and then supplied to key matrix circuit 19. With operation of a certain numerical key of circuit 19, the timing signal is delivered to the corresponding output line and then sent to data selector 18. Based on this signal, selector 18 selects the data of 3 bits out of CRTC14, and thus 1-shot pulse signal is delivered in the timing of the above selection. This pulse signal is sent to buffer 12 as the reading signal, and accordingly the address data of 6 bits delivered from CRTC14 is read into buffer 12 at that moment in the form of the key input code. This code is read out of buffer 12 by key input reading command KI given from CPU and then transferred to CPU. COPYRIGHT: (C)1981,JPO&Japio

Inventors

• 👤 Harumi Nakano

Bibliographic Details