Chapter 8 - Using MS-DOS
8-24
PL-5910 Series User Manual
Function 01h
Transmit 1 Byte Data
Transmits 1 byte data..
Input:
AH = 01h
AL = Transmission Data
DX = Port Number (0 to 3)
Output:
AH = Line Status (During timeout; bit 7 becomes 1)
AL = Transmission Data
Function 02h
Receive 1 Byte Data
Receives 1 byte of data. If characters are present in the buffer while the buffer is being
refreshed, these characters are returned. If there are no characters in the buffer, the
computer waits until a timeout occurs.
Input:
AH = 02h
DX = Port Number (0 to 3)
Output:
AH = Line Status (When no data; bit 7 becomes 1 (Timeout))
AL = Receive Data
Function 03h
Read Transmission Port Status
Reads the status of the transmission port.
Input:
AH = 03h
DX = Port Number (0 to 3)
Output:
AH = Line Status
AL = Modem Status
