Int 14H, Serial Port Handler; Use; Entry; Exit - Husky MP2500 Manual

25. INT 14H, Serial Port Handler

Use

Serial port control and I/O.

Entry

AH selects the function required, while other registers are used for
parameters, as follows.
DX indicates the serial port. As MP2500 is equipped with only one, COM2,
DX must be 01H (COM2).

Exit

Valid only when using IBM mode comms, not when in H
from many of the functions, the AX register indicates the communications
status as follows, while the other registers are preserved.
Bits in AH indicates the line status as follows, when set:
Bit Significance if set
7 Timeout (ignore other bits)
6 Transmit shift register empty
5 Transmit hold register empty
4 Line Break detected
3 Framing error
2 Parity error
1 Overrun error
0 Data ready (or in input buffer, if enabled)
Chapter 25: INT 14H, Serial Port Handler
mode. On exit
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