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N14NOTES.TXT
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1993-11-19
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This information was accidentally left out of the documention for
using the net14 driver. The net14 driver is a shell which installs
inself to manage the interrupt 14h for serial communications and
re-direct int 14h reads and writes to/from the ethernet network.
It then starts up another program which uses the int 14h interface
with the following programming interface:
Int 14h Function 00H: Initialize communications
Call With:
AH = 00H
AL = Ignored (serial communication programs use this for
additional communication parameters, which are un-used
in the net14 driver).
DX = Comm. port number to initialize
Returns:
AH is returned with the port status:
Bit: Meaning (if set):
---- -----------------
7 Timed-out
6 Transmit shift register empty
5 Transmit holding register empty
4 Break detected
3 Framing error detected
2 Parity error detected
1 Overrun error detected
0 Receive data ready
AL has the modem status:
Bit: Meaning (if set):
---- -----------------
7 Receive line signal detect
6 Ring indicator
5 Data-set-ready
4 Clear-to-send
3 Change in receive line signal detect
2 Trailing edge ring indicator
1 Change in data-set-ready status
0 Change in clear-to-send status
Int 14h Function 01H: Send Character
Call With:
AH = 01H
AL = Character
DX = Comm. port to send through
Returns:
Bit 7 of AH is zero if successful, otherwise Bit 7 of AH is one.
Int 14h Function 02H: Receive Character
Call With:
AH = 02H
DX = Comm. port to receive from
Returns:
Bit 7 of AH is zero if successful, otherwise Bit 7 of AH is one.
Character read is in AL if the call was successful.
Int 14h Function 03H: Get Comm. Port Status
Call With:
AH = 03H
DX = Comm. port to get status of
Returns:
AH is returned with the port status, and AL has the modem status.
(See function 00H above)
Notes:
In order to establish a connection, the following steps must be
followed in order:
1. Call function 00H with the port to initialize.
2. Send the following sequence to the port: one ascii 02 code
(control-B), the name of the machine to connect to (or its
IP address) one character at a time, and the ascii 03 code
(control-C).
Following a connection being established, the net14 driver
will ignore any control-C's and control-B's in the data stream
send or received. A connection can be closed by re-initializing
the comm. port (function 00H).
So, to use net14 with another application, first verify that the other
application uses interrupt 14 to write to the communications port.
In Kermit, for instance, this is done with "set port bios1". If the
application is using interrupt 14 to access the port, it will have
initialized it for you. Now send the ^Bhostname^C sequence out.
Once again, in kermit this is done by going to connect mode with
"connect" and then typing ^Bhostname^C. Net14 will deinstall itself
and close all connections when you exit the application.