Icom IC-7700 Service Manual page 12

3-4 MAIN CPU (IC604) PORT ALLOCATIONS (continued)
Pin
No.
23 Clock to the EEPRROM (HN58X2464TI).
24 Serial data from the EEPRROM (HN58X2464TI).
26 Clock signal to the EEPROM (DIGISEL UNIT; CAT24WC256).
27 Serial data from/to the EEPROM (DIGISEL UNIT; CAT24WC256).
30 RTTY keying.
31 Transverter control signal from the [ACC] connector.
21 PLL unlock signal.
5–
Address bus lines.
20
73–
Data bus lines.
71
84 WAIT signal (bus line control).
85 SEND signal.
86 Dual Port SRAM intrude signal.
87 "L" indicator control signal (bus control).
88 "H" indicator control signal (bus control).
89 READ data (bus contol).
90 Address data (bus contol).
94 PTT/ACC SEND input.
107 Squelch signal to the [ACC] connector.
109 Squelch signal.
35 External SEND (lead relay) signal output.
36 External SEND (IC relay) signal output.
37 Chip select signal to the Dual Port SRAM.
38 Chip select signal to the expander.
Description
3 - 6
IN/ Condtion
OUT
O
I/O
O
I/O
I "H"="space" is marked
"L"= T r a n s v e r t e r i s
I
activated.
I "L"=Unlocked
O
I/O
I "L"=Wait.
O "L"=TX
I
O "L"= lights.
O "H"= lights.
O
O
I "H"=TX
"H"= Squelch open (RX
O
LED lights)
"L"= Squelch open (Mute
O
OFF)
O "H"=Relay ON
O "H"=Relay ON
O "L"=SRAM is selected.
"L"= E x p a n d e r
O
selected.
i s