User guide

20 Registers
3.1 I/O Port Base Address
The registers of the cPCI/PCI/PCIe-7300A are shown in Table 3.1.
The base address of these registers is also assigned by the PCI
P&P BIOS. The assigned base address is stored at offset 18h of
the PCR. Therefore, users can read the PCR to know the base
address by using BIOS function call. Note that the cPCI/PCI/
PCIe-7300A registers are all 32 bits. Users should access these
registers by 32 bits I/O instructions.
The cPCI/PCI/PCIe-7300A occupies 8 consecutive 32-bit I/O
addresses in the I/O address space. Table 3.1 shows the I/O Map
of the cPCI/PCI/PCIe-7300A rev.B.
Address Read Write
Base + 0 DI_CSR DI_CSR
Base + 4 DO_CSR DO_CSR
Base + 8 AUX_DIO AUX_DIO
Base + C INT_CSR INT_CSR
Base + 10 DI_FIFO DI_FIFO
Base + 14 DO_FIFO DO_FIFO
Base + 18 - FIFO_CR
Base + 1C POL_CTRL POL_CTRL
Base + 20 8254_COUNT0 8254_COUNT0
Base + 24 8254_COUNT1 8254_COUNT1
Base + 28 8254_COUNT2 8254_COUNT2
Base + 2C 8254_CONTROL 8254_CONTROL
Table 3-1: I/O Port Base Address