NCR RealPOS 70, User Manual

Page: 246 / 306

12-6 Chapter 12: Cash Drawer Interface
Hardware/Firmware Interfaces
In some previously supported models, no preliminary interaction with
the hardware was required to determine the port address(s) used for
communication with the cash drawer; these data were instead obtained
from the registry. For the 7402, the port address is set dynamically by
the BIOS and hence the hardware must be queried to obtain this
information. This dictates the need for the generation of a
configuration cycle as described previously.
Configuration mechanism one utilizes two 32bit I/O ports located at
addresses 0x0CF8 and 0x0CFC. These two ports are:
•
32 ‐ bit configuration address port ‐ occupying I/O addresses 0x0CF8
through 0x0CFB.
•
32 ‐ bit configuration data port ‐ occupying I/O addresses 0x0CFC
through 0x0CFF.
Accessing a PCI function’s configuration port is a two step process:
•
Write the target bus number, physical device number, function
number and doubleword number to the configuration address port
•
Perform an I/O read from or a write to the configuration data port.
The ICH4 Configuration Address Register should be defined as
follows:
•
Configuration Space Mapping enabled
•
Bus number 0
•
Device number 31
•
Function number 0
•
GPIO base register offset address 0x58