Specifications

AMD Geode™ GeodeROM Functional Specification 87
9
Parallel Port BIOS Support 32087C
9.0Parallel Port BIOS Support
GeodeROM supports the standard INT 17h functions listed in Table 9-1 that pertain to the operation of up to three parallel
ports in the system:
9.1 INT 17h Parallel Port BIOS Functions Descriptions
This section lists those INT 17h functions supported in GeodeROM, the parameters that system software supplies to each
INT 17h function, and the values each function returns. The I/O address(es) of any port(s) in the system are stored in the
BDA by POST. The WORD-length addresses begin at 40:8h and can go through 40:Ch.
9.1.1 Function 00h - Print a Character
Description:
Sends a character to the parallel port. The function waits until the printer is not busy or until a timeout has occurred.
The caller can invoke Function 02h to check whether the printer is ready to accept a character.
Passed:
Returns:
Table 9-1. INT 17h Functions
Function Number/Name Page Number
Function 00h - Print a Character 87
Function 01h - Initialize Parallel Port 88
Function 02h - Get Port Status 88
Parameter Description
AH 00h
AL ASCII code of character to send
DX Port number; BDA location:
00h = 40:8h
01h = 40:Ah
02h = 40:Ch
Parameter Description
AH Port status:
Bit 7 = Printer ready
Bit 6 = Acknowledgement of last character
Bit 5 = Paper empty
Bit 4 = Printer selected
Bit 3 = I/O error
Bits [2:1] = Reserved
Bit 0 = Timeout error