Quatech QSC-100 - Manual (Page 11)

4 Address Map and Special Registers
This chapter explains how the four UARTs and special registers are addressed,
as well as the layout of those registers. This material will be of interest to programmers
writing driver software for the QSC-100.
4.1 Base Address and Interrupt Level (IRQ)
The base address and IRQ used by the QSC-100 are determined by the BIOS or
operating system. Each serial port uses 8 consecutive I/O locations. The four ports
reside in a single block of I/O space in eight byte increments, for a total of 32
contiguous bytes, as shown in Figure 5.
Base Address + 24 to Base Address + 31 Serial 4
Base Address + 16 to Base Address + 23 Serial 3
Base Address + 8 to Base Address + 15 Serial 2
Base Address + 0 to Base Address + 7 Serial 1
I/O Address Range Port
Figure 6 --- Port Address Map
All four serial ports share the same IRQ. The QSC-100 signals a hardware
interrupt when any port requires service. The interrupt signal is maintained until no
port requires service. Interrupts are level-sensitive on the PCI bus.
The base address and IRQ are automatically detected by the device drivers
Quatech supplies for various operating systems. For cases where no device driver is
available, such as for operation under DOS, Quatech supplies the "QTPCI" DOS
software utility for manually determining the resources used. See page 0 for details.
Quatech QSC-100 User's Manual 9