Modem Function (Base Address 8020h)

8020h - Modem Configuration Option Register (MCOR)

7

6

5

4

3

2

1

0

 

 

 

 

 

 

 

 

SRESET

LevIREQ

 

 

 

Enable

Enable

Enable

 

 

 

 

 

IREQ

Base and

Function

 

 

 

 

 

 

Limit

 

 

 

 

 

 

 

 

 

0

1

0

0

0

0

0

0

 

 

 

 

 

 

 

 

BIT 7 - SRESET: This bit when set clears all internal registers associated with the Modem function (except itself) and asserts the nMRESET pin .

BIT 6 - LevIREQ: This bit is read only and reads as a one to indicate level mode interrupts are used. Pulse mode interrupts are not supported.

BIT 5 - Not defined

BIT 4 - Not defined

BIT 3 - Not defined

BIT 2 - Enable IREQ Routing: This bit enables

(1)or disables (0) the Modem function from asserting nIREQ.

BIT 1 - Enable Base and Limit: This bit enables the on board modem I/O base decoder. If set, the on-board decoder is used to select the function. If cleared, the decoder is disabled and it is assumed that the host provides for the decoding. When the decode is disabled, the function is enabled, and is configured for 16 bits (and not in power-down mode), the signal - IOIs16 is always asserted. For multifunction

PCMCIA functionality, this bit must be set.

BIT 0 - Enable Function: This bit enables (1) or disables (0) the Modem function. While the Modem is disabled the SMC91C95 inhibits nMCS, IREQ is not generated for the Modem function and nINPACK is not returned for accesses to the Modem registers.

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SMC Networks SMC91C95 manual LevIREQ Enable, Pcmcia functionality, this bit must be set