CD1284 Datasheet, PDF (99/176 Pages) Intel Corporation – IEEE 1284-Compatible Parallel Interface Controller with Two High-Speed Asynchronous Serial Ports

IEEE 1284-Compatible Parallel Interface Controller — CD1284
6.4.3
6.5
Modem Service
/* The following routine services the modem change service request. Context switch
is set up by activating the SVCACKM* input, reading the MIVR. The routine reads the
MISR register to determine which modem signal(s) changed. Channel status is an
externally defined variable that this routine updates. */
service_mdm( )
{
char
vector, channel;
vector = inportb(SVCACKM);
/* retrieve and save transmit interrupt
value */
channel = inportb(MICR) >> 2;
/* extract channel number from the RICR*/
mdm_status[channel] = inportb(MISR);/* get status of which modem signals
changed */
outportb(EOSRR, 0x00);
/* write dummy value to EOSRR to terminate
*/
}
Parallel Channel Service Routines
In most respects, the parallel channel functions in the same way as the two serial channels, but the
Poll mode operation is different. Its functions can be performed in a couple of ways. The MPU is
only involved with the parallel channel in performing interrupt generation services. All other
channel operations are completely separate. Since the MPU is involved in the interrupt structure,
aspects of its behavior must be taken into account.
Datasheet
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