SCD1284 INTEL [Intel Corporation], SCD1284 Datasheet - Page 99

• Manufacturer Part Number: SCD1284
• Description: IEEE 1284-Compatible Parallel Interface Controller with Two High-Speed Asynchronous Serial Ports
• Manufacturer: INTEL [Intel Corporation]

6.4.3
6.5
Datasheet
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( )
{
value */
changed */
*/
}
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.
char
vector = inportb(SVCACKM);
channel = inportb(MICR) >> 2;
mdm_status[channel] = inportb(MISR);/* get status of which modem signals
outportb(EOSRR, 0x00);
vector, channel;
IEEE 1284-Compatible Parallel Interface Controller — CD1284
/* retrieve and save transmit interrupt
/* extract channel number from the RICR*/
/* write dummy value to EOSRR to terminate
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