Compaq 850 manual Parallel Interface Programming, Parallel Interface Configuration

Technical Reference Guide

5.5.4 PARALLEL INTERFACE PROGRAMMING

Programming the parallel interface consists of configuration, which typically occurs during POST, and control, which occurs during runtime.

5.5.4.1 Parallel Interface Configuration

The parallel interface must be configured for a specific address range (LPT1, LPT2, etc.) and also must be enabled before it can be used. When configured for EPP or ECP mode, additional considerations must be taken into account. Address selection, enabling, and EPP/ECP mode parameters of the parallel interface are affected through the PnP configuration registers of the LPC47B357 I/O controller. Address selection and enabling are automatically done by the BIOS during POST but can also be accomplished with the Setup utility and other software.

The parallel interface configuration registers are listed in the following table:

Table 5–10. Parallel Interface Configuration Registers

Table 5-10.

Parallel Interface Configuration Registers

Index			Reset
Address	Function	R/W	Value
30h	Activate	R/W	00h
60h	Base Address MSB	R/W	00h
61h	Base Address LSB	R/W	00h
70h	Interrupt Select	R/W	00h
74h	DMA Channel Select	R/W	04h
F0h	Mode Register	R/W	00h
F1h	Mode Register 2	R/W	00h

Compaq Deskpro EXS and Workstation 300 Personal Computers 5-13

Featuring the Intel Pentium 4 Processor

First Edition - December 2000