µPD6121, 6122

13

6.

DOUBLE-INPUT OPERATION

All keys are provided with a multiple-input prevention circuit. When two or more keys are pressed simulta-

neously, no signal is transmitted; but when the keys K21 and K22, K21 and K23, or K21 and K24 are pressed

126 ms or longer after K21 is pressed, transmission is performed in this mode.

Double-input key operation is ideally suited for tape recording error prevention applications.

Double-Input Operation Key Codes

KEY

K21 + K22

1010110

0/1

K21 + K23

0110110

0/1

K21 + K24

1110110

0/1

Double-Input Operation Timing

1 Double-input transmission

2 No operation

3 No operation

4 No operation

K21 code transmission

t > 126 ms

K21

push

K22/K23/K24

push

K21 code transmission

36 ms < t < 126 ms

K21

push

K22/K23/K24

push

Transmission stop

–36 ms < t < 36 ms

K21

push

K22/K23/K24

push

No transmission

K21

push

K22/K23/K24

push

t > 126 ms

K22/K23/K24 code transmission

Transmission stop