IC-4 is an 8-Channel Data Selector switch that is used to read the status of various switches or buttons from the front of the rig, as well as the microphone.

The Processor (IC-1) chooses which data input line to read by setting an address on pins 11-13, and setting the Disable pin low. IC-4 then passes the state of the selected input line to the processor on pin 14.

TC4512 Pinout

TC4512BP_datasheet

IC-4 Pin 1: Band Down/Microphone Down (Not pressed)

IC-4 Pin 1: BD/MD

 

IC-4 Pin 2: Band Up/Band Down (Not pressed)

IC-4 Pin 2: BU/BD

 

IC-4 Pin 3: Memory In button (Not pressed)

IC-4 Pin 3: MIN

 

IC-4 Pin 4: Memory Recall (Not Pressed)

IC-4 Pin 4: MR

 

IC-4 Pin 5: A=B Switch (Not Pressed)

IC-4 Pin 5: A=B

 

IC-4 Pin 6: Lock (Not Pressed)

IC-4 Pin 6: LOK

 

IC-4 Pin 7: Step Switch (Not Pressed)

IC-4 Pin 7: STP

 

IC-4 Pin 8: Ground

IC-4 Pin 8: GND

 

IC-4 Pin 9: 1 MHZ Switch (Not Pressed)

IC-4 Pin 9: MHS

 

IC-4 Pin 10: Ground

IC-4 Pin 10: GND

 

IC-4 Pin 11-13 Address Select Pins A, B C

IC-4 Pin 11: A

 

IC-4 Pin 12: B

 

IC-4 Pin 13: C

 

IC-4 Pin 14: Output to processor

IC-4 Pin 14: Z

 

IC-4 Pin 15: Disable (Chip Select Low)

IC-4 Pin 15: Disable

 

IC-4 Pin 16: + 5 volt source

IC-4 Pin 16: +Vss