Manual P104-DIO-96
8
Installing the Hardware
Before installing the board, please run Setup.exe. The Setup program can be used to assist in
configuring the two switches on the board. Our setup program will lead the user through the process of
setting the options on the board (the program does not set the options on the board).
The PCI bus clock trace length from the CPU to the cards in the stack is tuned so that the clock edge
arrives at the interface when data is valid. Since boards in the PC/104 stack are at different distances
from the CPU, provision is made on the CPU board to supply four clock signals with compensating trace
lengths. Two signals from other groups must be likewise selected: IDSEL and INT. When the PCI bus is
being initialized, the operating system will enable each card with a hard-wired select line and read it's
configuration registers. An address is assigned, space in the memory map and I/O map is reserved, etc.
Similarly, the CPU's interrupt controller resources (INTA, INTB, INTC, INTD) will be distributed among
the cards in the stack. A set of four-to-one multiplexers and two slide switches are used to select which
PCI clock, IDSEL and INT lines are routed to the board’s PCI bus interface.
Only four boards are allowed in a PCI-Plus stack, each board must get a specific set of signals. These
signals are selected with two slide switches, labeled SEL-1 and SEL-2, which form a binary value to
control the mux (SEL-1 is the least significant bit and SEL-2 is the most significant bit). If the board is
closest to the CPU, slide both switches to the right. This will select the signal with the longest trace on
the CPU board (signal group 0). If this product is the farthest board from the CPU, slide both switches to
the left. This will select the signal with the shortest trace on the CPU board (signal group 3). Place the
SEL-1 switch to the left and SEL-2 to the right to select signal group 1, place the SEL-1 switch to the right
and SEL-2 to the left to select signal group 2.
