3 ISA and PC/104 Drivers
ISA and PC/104 Bus Considerations
In this section...
“Introduction” on page 3-2
“I/O Mapped” on page 3-2
“Memory Mapped” on page 3-3
Introduction
When w ritingx PC Target drivers for ISA and PC/104 devices, consider the
memory access method. A PCI device can be either port mapped or memory
mapped. Most ISA and PC/104 boards are port mapped. Those that are
memory mapped typically need large register banks or are interfaced via
dual-port memory.
Note ThexPC Target kernel does not support ISA and PC/104 PNP boards.
This means that you can write xPC Target device d rivers only for ISA and
PC/104 boards for which you can set the base address manually. To manually
set the base address, insert jumpers or move DIP switches on the board.
• Port mapped
The b ase port address on the bo ard is set via jumpers or switches. You
might need to r es et these addresses if there are conflicts.
• Memory mapped
The I/O and memory on the board are set via jumpers or switches. You
might need to r es et these addresses if there are conflicts.
I/O Mapped
The base port address on the board is set via jumpers or switches. Drivers
cannot discover these addresses on their own; you must specify these
addresses to the driver.
3-2
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