Int 0B

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IRQ3 - SERIAL COMMUNICATIONS (COM2)

Desc: Automatically asserted by the UART when COM2 needs attention, if the UART has been programmed to generate interrupts

Notes: The TOPS and PCnet adapters use this interrupt request line as an alternate. On PS/2s, COM2 through COM8 share this interrupt; on many PC's, COM4 shares this interrupt. May be masked by setting bit 3 on I/O port 21h. DOS 3.3+ revectors IRQ3 to a stack-switching routine unless STACKS=0 has been set in CONFIG.SYS. MS/PC-DOS use the IBM Interrupt Sharing Protocol (see #02568) when hooking this IRQ

See Also: INT 0C"COM1" - INT 53"DESQview" - INT 5B"DoubleDOS" - INT 7B"GO32"

Category: Hardware - Int 0Bh - I

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