PURPOSE: To form a gate array easily by using TTL for the control circuit of a book keyboard.
CONSTITUTION: The output 11 of an oscillator 1 is inputted as a shift clock to a register 2 which converts 16 parallel sensor inputs into a serial signal and the output 21 of the register 2 is inputted to a counter 3, whose counter output 31 is latched by a latch circuit 4. The oscillator output 11 is also inputted to a counter 5 as a clock and a decoding circuit 6 generates a keyboard scan output. The return signal from the keyboard is passed through an encoding circuit 7, and when a key is depressed, the output 51 of the counter 5 and the output 71 of the encoding circuit 7 are inputted to a latch circuit 8 and a flip-flop (FF) FF101 is set high through a line 72 and a FF10. The setting of the FF101 actuates a key code output control circuit 12 and key code data is sent out of an output control circuit 9 to a line 91 and serial data 141 is sent out to a central processor through a parallel-serial converting circuit 14.
TOBA TAKUO
KUBO JIROU
