faq	Number of Cards

Are we limited to a total of four PCI cards in one host machine?

The driver is limited to 10 cards that can be used simultaneously. It's documented in the parameter PCL_HANDLES in AVPCL.H. In the same file you find the parameter PCL_BASE_PCI_LAST that limits the number of PCI pseudo-addresses to 4, but this parameter is only used by the test programs PclTest and IntTest to find out if a given address is valid. The driver itself doesn't care about that.

Each card may be opened using the base address defined in the header file? eg PCL_BASE_PCI_1, PCL_BASE_PCI_2 etc. pclOpen (&m_hAVPCLDriver[card], PCL_BASE_PCI_1);

Yes, that's right. If you want to use more than 4 cards, you have to define additional pseudo-addresses like this:
#define PCL_BASE_PCI_5 0x1005 /* 5th PCL PCI card */
#define PCL_BASE_PCI_6 0x1006 /* 6th PCL PCI card */
#define PCL_BASE_PCI_7 0x1007 /* 7th PCL PCI card */
#define PCL_BASE_PCI_8 0x1008 /* 8th PCL PCI card */
#define PCL_BASE_PCI_9 0x1009 /* 9th PCL PCI card */
#define PCL_BASE_PCI_10 0x100A /* 10th PCL PCI card */

If you want to use more than 10 PCI cards simultaneously, we have to increase the PCL_HANDLES parameter.

On a new reset of the host machine, PCL_BASE_PCI_1 will still open the same card as previously - assuming no hardware is removed?

This depends on the PCI enumeration of the system's BIOS and the operating system. But on all machines I know of, the result of the enumeration is the same on every boot, if the hardware configuration was not changed.