Chapter 9. IEEE-1284 Parallel Port Interface
70
ADDRESS MAPPING
The address mapping for the PC standard architecture and the ZT 8905 is shown below. The on-
board port may be disabled to allow an STD 32 LPT port to be used.
Parallel Port
PC Port Address
ZT 8905 Port Address
LPT1
3BC (typically)
378-37F - Normal, Extended, EPP Modes
378-37A, 778-77A - ECP Mode
INTERRUPT SELECTION
The interrupt mapping for the PC standard architecture and the ZT 8905 is shown below.
Parallel Port
PC Interrupt
ZT 8905 Interrupt
LPT1
IR5
IR7 or disabled for off-board LPT support
DMA SELECTION
DMA may be configured for ECP mode in software. DMA channel 0 is dedicated for ECP support and
may be used by application software. The BIOS does not use DMA for any data transfers.
Applications needing DMA support must configure the parallel port with appropriate initialization code.
PROGRAMMABLE REGISTERS
The following topics illustrate the programmable registers for the Normal/Extended mode parallel port
interface. For EPP and ECP information, consult the National Semiconductor PC87303 data sheet
(National LIT# 112904-001)
Line Printer Data Register
Register: Line Printer Data
Address: 378h
Access: Read and Write
D7
D6
D5
D4
D3
D2
D1
D0
7
6
5
4
3
2
1
0
Line Printer Data Register
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Содержание ZT 8905
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