1 i/o port base address – ADLINK PCI-7300A User Manual
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Registers
• 17
3.1 I/O Port Base Address
The registers of the cPCI/PCI-7300A are shown in Table 3.1. The base 
address of these registers is als o 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-7300A registers are all 32 bits. Users should access these 
registers by 32 bits I/O instructions. 
 
The PCI-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 PCI-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
 
Legend: 
DI_CSR: Digital input control & status register 
DO_SCR: Digital output control & status register 
AUX_DIO: Auxiliary digital I/O port 
INT_CSR: Interrupt control and status register 
DI_FIFO: DI FIFO direct access port 
DO_FIFO: DO FIFO direct access port 
FIFO_CR: FIFO almost empty/full programming register 
POL_CTRL: Polarity control register for the control signals 
 
Caution: 
 
1. I/O port is 32-bit width
2. 8-bit or 16-bit I/O access is not allowed.