Which bios interrupt provides serial port services andlist down names of 9 pins of db-9connector.

To help interrupt serial driven communications, the PC utilizes two interrupts, IRQ 3 and IRQ 4.

INT 0Bh and INT 0Ch are the BIOS interrupt

It patches the COM1,COM2 when you call the Com Init Intr routine: interrupt vectors (int 0Ch int 0Bh), allowing IRQ 4 and IRQ3 in the 8259A PIC.

IRQ 3  0Bh  Serial port 2

IRQ 4  0Ch  Serial port 1

9 pins of DB-9 connector -

1       RTS, Request to Send

2       CTS, Clear to send

3       GND,Ground

4       RXD,Receive Data

5      TXD, Transmit Data

6       DTR, Data Terminal Ready

7       DSR, Data Set Ready

8       RI, Ring Indicator

9       DCD,Data carrier detect

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