Table 5-10. Parallel Interface; Table; Table 5-11. Parallel Interface; Addresses - HP Deskpro EX Technical Reference Manual

Chapter 5 Input/Output Interfaces
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. 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
Parallel Interface Configuration Registers
Index
Address Function
30h Activate
60h Base Address MSB
61h Base Address LSB
70h Interrupt Select
74h DMA Channel Select
F0h Mode Register
F1h Mode Register 2
5.5.4.2 Parallel Interface Control
The BIOS function INT 17 provides simplified control of the parallel interface. Basic functions
such as initialization, character printing, and printer status are provide by subfunctions of INT 17.
The parallel interface is controllable by software through a set of I/O mapped registers. The
number and type of registers available depends on the mode used (SPP, EPP, or ECP). Table 5-11
lists the parallel registers and associated functions based on mode.
Table 5–11. Parallel Interface Control Registers
I/O
Address
Base
Base + 1h
Base + 2h
Base + 3h
Base + 4h
Base + 5h
Base + 6h
Base + 7h
Base + 400h
Base + 400h
Base + 400h
Base + 400h
Base + 401h
Base + 402h
Base Address:
LPT1 = 378h, LPT2 = 278h, LPT3 = 3BCh
5-12 Compaq Deskpro EX Series of Personal Computers

Table 5-10.

Table 5-11.
Parallel Interface Control Registers
Register
Data
Printer Status
Control
Address
Data Port 0
Data Port 1
Data Port 2
Data Port 3
Parallel Data FIFO
ECP Data FIFO
Test FIFO
Configuration Register A
Configuration Register B
Extended Control Register
First Edition – August 2000
Reset
R/W Value
R/W 00h
R/W 00h
R/W 00h
R/W 00h
R/W 04h
R/W 00h
R/W 00h
SPP EPP
Mode Mode
Ports Ports
LPT1,2,3 LPT1,2
LPT1,2,3 LPT1,2
LPT1,2,3 LPT1,2
-- LPT1,2
-- LPT1,2
-- LPT1,2
-- LPT1,2
-- LPT1,2
-- --
-- --
-- --
-- --
-- --
-- --
ECP
Mode
Ports
LPT1,2,3
LPT1,2,3
LPT1,2,3
--
--
--
--
--
LPT1,2,3
LPT1,2,3
LPT1,2,3
LPT1,2,3
LPT1,2,3
LPT1,2,3