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1990-09-29
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KISS Proms for use with TheNode.
The disk has two prom images for for use with TNC2 (or clones), and one
for use with the TNC220.
KISS is as released with the TCPIP package. I have used this code, and
it seems to work, but it does have loopholes in its buffer management. As
I have experienced buffering problems with other KISS mode TNCs with TheNode,
i've done a version which will reset if it runs out. This is a bit drastic,
but should keep the system going. (Higher level software will retry the
discarded messages). If it improves things, I'll refine it to discard the
oldest. The new eprom image is in the file JKISS.
220KISS is a version of JKISS, modified to run on the TNC220. This version
only supports the VHF port (port 2) at 1200 baud,and the aync link to the PC
is fixed at 2400. The DCD led is driven by software, but is controlled by the
DCD signal from the modem (ie DCD processing is the same as with the TNC2 -
the SOFTDCD mode of the 220 is not implemented). Other versions are possible
if there is sufficient interest - the main problem is that the KISS command
set would have to be extended to include commands for port and speed switching.
Note the software is now set up to run with the clock speed jumper in the
'Low' speed position - several people have had problems running in the 'Fast'
mode.
Version of these proms with CWID are still planned - as soon as I find time!
For those of you unfamiliar with KISS TNCs, the STA led indicates frames
being received from the PC and the CON led frames being sent to the PC. On
powerup, some LEDS should flash about 3 times - which ones depends on the
version and the RAM size in the TNC.
John Wiseman, G8BPQ
12/4/89
Ver 3.56 BETA
Please note the following has not yet been fully tested.
Multidropped KISS. (TNC2 and clones only)
From version 3.56, I have implemented a system to allow more than one
KISS-like TNC to connect to a single Async port. This is primarily for
those running machines with little expansion capability, but can also
enable the TNCs and transceivers to be located remotely from the PC with
a simple 3 wire link. This could be useful on the lower frequencies, where
QRM from the PC blocks the receiver ( I have real problems running a 50meg
RX near the PC). A simple checksum is also added to each packet, to
reduce the risk of corruption if running on long leads (or even over
a modem link).
The system uses polling to prevent contention on the link. Each TNC must
run the enclosed JKISSP program, and each must have a different 'address'
byte patched in at location 20hex. The PORTS PROTOCOL must be set to
MULTIKISS, and the CHANNEL set to correspond to the address in the PROM -
CHANNEL Address (in byte 20h of PROM)
A 00h
B 10h
C 20h
D 30h etc
In theory you can have up to 16, but in practice the maximum will depend
on the power of the PC and the speed of the radio ports.
Wiring.
PC TNC 1 TNC 2
GROUND 7 ---------------7----------------7----------- etc
TXD 2 ---------------2----------------2----------- etc
RXD 3 -------------------------------------------- etc
| |
- -
^ ^
| |
3 3
-
^ is a diode (1N914 or similar)
With some TNCs and serial cards, a pulldown resistor may be required
from pin 3 on the PC (10k to -12v is suggested). Thanks to G3ZFJ for this
information.