For example, if you have a board configured with the control block at address 0x300, the ports consecutive and
contiguous starting at address 0x100, and an IRQ of 0x5 on all ports, the values in the Registry are:
Serial2 subkey:
PortAddress = REG_DWORD 0x100
Interrupt = REG_DWORD 5
DosDevices = REG_SZ COM3
InterruptStatus = REG_DWORD 0x500
PortIndex = REG_DWORD 1
Serial3 subkey:
PortAddress = REG_DWORD 0x108
Interrupt = REG_DWORD 5
DosDevices = REG_SZ COM4
InterruptStatus = REG_DWORD 0x500
PortIndex = REG_DWORD 2
Serial4 subkey:
PortAddress = REG_DWORD 0x110
Interrupt = REG_DWORD 5
DosDevices = REG_SZ COM5
InterruptStatus = REG_DWORD 0x500
PortIndex = REG_DWORD 3
Serial5 subkey:
PortAddress = REG_DWORD 0x118
Interrupt = REG_DWORD 5
DosDevices = REG_SZ COM6
InterruptStatus = REG_DWORD 0x500
PortIndex = REG_DWORD 4
Serial6 subkey:
PortAddress = REG_DWORD 0x120
Interrupt = REG_DWORD 5
DosDevices = REG_SZ COM7
InterruptStatus = REG_DWORD 0x500
PortIndex = REG_DWORD 5
Serial7 subkey:
PortAddress = REG_DWORD 0x128
Interrupt = REG_DWORD 5
DosDevices = REG_SZ COM8
InterruptStatus = REG_DWORD 0x500
PortIndex = REG_DWORD 6
Serial8 subkey:
PortAddress = REG_DWORD 0x130
Interrupt = REG_DWORD 5
DosDevices = REG_SZ COM9
InterruptStatus = REG_DWORD 0x500
PortIndex = REG_DWORD 7
Serial9 subkey:
PortAddress = REG_DWORD 0x138
Interrupt = REG_DWORD 5
DosDevices = REG_SZ COM10
InterruptStatus = REG_DWORD 0x500
PortIndex = REG_DWORD 8
The InterruptStatus entry being 0x500 is a bit unusual; it’s the base address of the first port plus 0x400. This
would normally be an alias of the first port, but the board uses this aliased address for the status register.
Manual 104-COM-8S
13