Int 0C  - IRQ4 - Serial Communications (com1)                              [H]

Desc:  automatically asserted by the UART when COM1 needs attention, if the
     UART has been programmed to generate interrupts
BUG:   this vector is modified but not restored by Direct Access v4.0, and
     may be left dangling by other programs written with the same version
     of compiled BASIC

Notes: on many PC's, COM3 shares this interrupt
   may be masked by setting bit 4 on I/O port 21h

See Also: INT 0B"COM2",INT 54"DESQview",INT 5C"DoubleDOS",INT 7C"GO32"