5 - 5• CPU (FRONT UNIT; IC1)PinNo.PortName Description I/O1−3 KR1−KR3 Dealer-programmable keys input. I10 CCS Chip-select signal to the attached optional unit. O19−21CENC0−CENC2 CTCSS/DTCS signal. O23 DUSEFrequency response of tone filter (IC5)switching control.“Low”=While transmitting.O24 IPTT PTT input.“Low”=PTT is pushed. I25 HANG Microphone on/off hook detect.“Low”=The microphone is off hook. I30 PLST PLL strobe to the PLL IC (MAIN UNIT; IC4, pin 11). O34 ULCKPLL unlock detect signal from the PLL IC(MAIN UNIT; IC4, pin 7).“Low”=While the PLL circuit is unlocked.I35 LED1 Key indicator LED for [P1] (DS9) control.“High”= Lights. O36 LED2 Key indicator LED for [P2] (DS8) control.“High”= Lights. O37 LED3 Key indicator LED for [P3] (DS7) control.“High”= Lights. O28 POSW [PWR] key input.“Low”=Pushed. I39 DSDA Serial data to the D/A converter (MAIN UNIT;IC20, pin 6). O43 SENC DTMF signals to the LPF (IC5, pin 3). O44 BEEP Beep audio. O45 SDEC DTMF signals. I46 CDEC CTCSS/DTCS signals. I48 BATV Power supply voltage. I49 LVIN VCO lock voltage. I50 RSSI Received signal strength level signal from the IFdemodulator IC (MAIN UNIT; IC1, pin 12). I51 TEMP Temperature sensing voltage. I52 AFVI [VOL] dial (R14) input. (divided voltage of “5V”line) I59 RES CPU reset signal from the reset IC (IC8, pin 1).“Low”=CPU is reset. I69 CSFT CPU clock shift signal to the clock frequencyshift switch (D6). O71 DAST Strobe signal to the D/A converter (MAINUNIT; IC18, pin 7). O72 IGSW Ignition SW input. I75 NOIS Noise signal from the IF demodulate IC ( MAINUNIT; IC1, pin 13). I82 ESDA Serial data to the EEPROM (IC3, pin 5). O85 ESCL Clock signal to the EEPROM (IC3, pin 6). O86 PWON Transceiver's power control.“High”=Power ON. I87 CH4L Channel indicator LED for [CH4] (DS3) control.“High”= Lights. O88 CH3L Channel indicator LED for [CH3] (DS4) control.“High”= Lights. O89 CH2L Channel indicator LED for [CH2] (DS5) control.“High”= Lights. O90 CH1L Channel indicator LED for [CH1] (DS6) control.“High”= Lights. O95 LIGT2 Key backlight LED (DS1, DS2) control.“High”=Backlight is ON. O96 TLED TX indicator LED (DS10) control.“High”= Lights red (While transmitting). O97 RLED RX indicator LED (DS10) control.“High”= Lights green (While receiving). OPinNo.PortName Description I/O98 SCKSerial clock signal to the PLL IC (IC4, pin 9)and D/A converters (IC17, pin 3/IC18, pin 8/IC20, pin 7).O99 SO Serial data to the PLL IC (IC4, pin 9) and D/Aconverters (IC17, pin 3/IC18, pin 8/IC20, pin 7). O100 KR0 Input ports for dealer-programmable keys. I• EXPANDER (MAIN UNIT; IC17)PinNo.LineName Description4 RXC T8V, R8V lines and RX VCO ON/OFF control.5 AFON AF mute SW (Q35) control.“Low”=Mute6 NWC• RX band width switching signal to the 2nd IFfi lter SW (D56, D57).“Low”=Narrow mode• RX band width switching signal to the phaseshifter SW (Q5).“Low”=Wide mode7 RMUTAF mute signal to the analog switch (IC3,pins 12, 13).“Low”=While the squelch is close or transmitting.12 HORNOExternal device control.“Low”=Pin 6 of OPC-1939 or pin 10 of OPC-2078 (if connected) is “Low.”13 TMUTTransmit mute signal to the transmit mute switch(Q46).“High”=Transmitting is muted.• D/A CONVERTER (MAIN UNIT; IC18)PinNo. Description2, 3 MIC signal level adjustment.4, 5 RX AF/MIC signal level adjustment.16, 17 Tone signal level adjustment.18, 19 Oscillation frequency control voltage to the referencefrequency oscillator (X2).20, 21 Modulation signal level adjustment.22, 23 Beep sound loudness adjustment.24, 25 Squelch threshold level adjustment.• D/A CONVERTER (MAIN UNIT; IC20)PinNo.LineName Description1 T1• While receivingTuning voltage to the tuned BPF (D4, D8).• While transmittingTX power level setting signal to the APC AMPIC2).2 T2 Tuning voltage to the tuned BPF (D9, D10).3 TLVA Oscillation frequency correcting voltage to the TXVCO (Q13, D16, D18, D31, D53).4 RLVA Oscillation frequency correcting voltage to the RXVCO (Q14, D33, D34, D52).5-5 PORT ALLOCATIONS