DESCRIPTION OF PIN FUNCTIONS

PIN NO.

NAME

SYMBOL

TYPE

DESCRIPTION

 

 

 

 

 

16

n16 Bit

nMIS16

I with pullup

Input. When low, it indicates a 16 bit modem,

 

Modem

 

 

otherwise the modem is 8 bit wide. Used to

 

 

 

 

determine if nIOIS16 (PCMCIA) and nIOCS16

 

 

 

 

(ISA) need to be asserted for modem cycles.

 

 

 

 

The value of this pin may change from cycle

 

 

 

 

to cycle.

 

 

 

 

 

110

EEPROM

EESK

O4

Output. 4μs clock used to shift data in and out

 

Clock

 

 

of the serial EEPROM.

 

 

 

 

 

109

EEPROM

EECS

O4

Output. Serial EEPROM chip select.

 

Chip Select

 

 

 

 

 

 

 

 

108

EEPROM

EEDO/

O4

Output. Connected to the DI input of the serial

 

Data Out

SDOUT

 

EEPROM.

 

 

 

 

 

107

EEPROM

EEDI

I with pull-

Input. Connected to the DO output of the

 

Data In

 

down

serial EEPROM.

 

 

 

 

 

103,

I/O Base

IOS0-IOS2

I with pullup

Input. External switches can be connected to

105, 106

 

 

 

these lines to select between predefined

 

 

 

 

EEPROM configurations. The values of these

 

 

 

 

pins are readable. These pins are used in ISA

 

 

 

 

mode only. If in PCMCIA mode, these pins

 

 

 

 

are not used.

 

 

 

 

 

9

nTransmit

nTXLED

OD16

Internal ENDEC - Transmit LED output.

 

LED

 

 

 

 

nTransmit

nTXEN

O162

External ENDEC - Active low Transmit

 

Enable

 

 

Enable output.

 

 

 

 

 

12

nRoard

nBSELED

OD16

Internal ENDEC - Board Select LED activated

 

Select LED

 

 

by accesses to I/O space (nIORD or nIOWR

 

 

 

 

active with AEN low and valid address decode

 

 

 

 

for ISA, and with nREG low and and “Enable

 

 

 

 

Function” bit in the ECOR register is high for

 

 

 

 

PCMCIA). The pulse is stretched beyond the

 

 

 

 

access duration to make the LED visible.

 

Receive

RXD

I with pullup

External ENDEC - NRZ receive data input.

 

Data

 

 

 

 

 

 

 

 

 

 

 

14

 

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SMC Networks SMC91C95 manual Eeprom Eesk, Eeprom Eecs, Eeprom Eedo, Sdout Eeprom, Eeprom Eedi, IOS0-IOS2, Led, Rxd