HP Deskpro EX, Техническое справочное руководство, Страница: 106 / 214

Chapter 5 Input/Output Interfaces
5-12 Compaq Deskpro EX Series of Personal Computers
First Edition – August 2000
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
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
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
Table 5-11.
Parallel Interface Control Registers
I/O
Address
Register
SPP
Mode
Ports
EPP
Mode
Ports
ECP
Mode
Ports
Base Data LPT1,2,3 LPT1,2 LPT1,2,3
Base + 1h Printer Status LPT1,2,3 LPT1,2 LPT1,2,3
Base + 2h Control LPT1,2,3 LPT1,2 LPT1,2,3
Base + 3h Address -- LPT1,2 --
Base + 4h Data Port 0 -- LPT1,2 --
Base + 5h Data Port 1 -- LPT1,2 --
Base + 6h Data Port 2 -- LPT1,2 --
Base + 7h Data Port 3 -- LPT1,2 --
Base + 400h Parallel Data FIFO -- -- LPT1,2,3
Base + 400h ECP Data FIFO -- -- LPT1,2,3
Base + 400h Test FIFO -- -- LPT1,2,3
Base + 400h Configuration Register A -- -- LPT1,2,3
Base + 401h Configuration Register B -- -- LPT1,2,3
Base + 402h Extended Control Register -- -- LPT1,2,3
Base Address:
LPT1 = 378h, LPT2 = 278h, LPT3 = 3BCh