Technical information

NewBIOS Reference Serial Solutions
the port number on the card so that it can identify the source of
any interrupt- port 1 is not assumed to be COM1 and so on.
Type 1 compatible cards:
DigiBOARD PC/4 and PC/8.
These use similar interrupt sharing hardware to the Brain
Boxes Lynx and Quad cards, but each card has two status
registers and two interrupt lines. However the second status
register is usually ignored on the Digiboard card. When one one
interrupt and status register is being used set the card up as a
Brain Boxes Lynx card.
For the two status register setup: The installation guide gives an
address for the status register for the odd-numbered interrupt,
and the address of the status register for the even-numbered
interrupt line is one greater than this.
Set up a DigiCHANNEL card as two Brain Boxes cards,
with status registers at adjacent addresses, the first used with the
odd-numbered interrupt line and the second with the even-
numbered interrupt line.
Flynix-8 FAT-011 and compatibles- type 2.
This has eight ports arranged in two groups of 4, each
group having a status register and interrupt line associated with
it. The information associated with a Flynix card is as follows:
BX = Address group status register-read only.
CL = Port number, 0 for port 1 on the card, 1 for
port 2 etc.
CH = IRQ line- writable only for the last port of a
group, otherwise read only.
The irq line and status register address are the same for all ports
in a group. The status register address is calculated from the i/o
address of the last port in a group (port 4 or port 8) by
NewBIOS, so is a read-only field, any value written will be
ignored. Setting the IRQ for the last port in a group sets the
IRQ for the remaining ports in a group, and can only be read
from those ports. NewCOM needs to know the port number on
Chapter 5 Page 101