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Technical Reference Guide
Compaq Deskpro EXS and Workstation 300 Personal Computers
Featuring the Intel Pentium 4 Processor
First Edition - December 2000
5-13
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
Address Function R/W
Reset
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