(originally from OE5DXL, english translation by DL9RDZ)This text is not jet prepared for general distribution.
test-version L2PCX, HAMWARE - (C) OE5DXL commercial usage prohibited
resident multi-port AX.25-driver for IBM-compatible and plug-in-modem(s) for RS232, 9600bit/s FSK w/ G3RUH-scrambling, power supply from the interface. IC's: TL064, 4013, 4538
Terminal-interface with WA8DED-hostmode
(detailed information about hostmode interface not yet included, see e.g. documation of the Atari-version L2STX)
L2PCX can be operated at 1200bit/s, but only in the operational mode used with the FSK-modems. This can't be adjused just with changing Pins for "Baycom". For 1200bit/s various other driver software does exist.
Before building or bying a modem, the PC should be testet without modem, wheater it's RS232-interface is compatible, resp. the CPU can handle the interrupts properly (see below).
For testing a modem, you should install L2PCX for the according RS232-interface, because otherwise the power supply on the status lines may not be present.
command line parameters:
-U unload -Iparameters for separate ports are set after the -Ptrap-int of the WA8DED interface, default 253 = FDh -P AX.25 port (currently only P1 supported) -B size of data-buffer in 32byte, default 800 -xx Test Off -- some % less cpu time consumed (command is NOT -xx, is not yet published)
-P-Bbit/s bit/s Port 1 (150 to 9600), default 9601 add 1: turns on G3RUH-scrambling (-B9601) add 2: sets DTR to +12V for AFSK-modems (-B1202) -P -C used COM port, according to BIOS, default COM1 -P -I interrupt of interface (-I3), default I4 -P -A base-adress of interface (dezimal!) (-A760) default 1016
all possible parameters after -Px can be combined. In case you need parameters to change the default values, you can simplify the loading with a .BAT-file. start with: (examplex)
! IntTest ! bit/s ! Scrambl ! COMnr ! INTnr ! Adrs !
---------------------------+---------+-------+---------+-------+-------+------+
L2PCX ! ON ! 9600 ! ON !f.bios ! INT4 !n.bios!
L2PCX -U ! ------------------ Unload ----------------------!
L2PCX -P1 -B1200 ! ON ! 1200 ! OFF !f.bios ! INT4 !f.bios!
L2PCX -P1 -B9600 ! ON ! 9600 ! OFF !f.bios ! INT4 !f.bios!
L2PCX -P1 -B9601 ! ON ! 9600 ! ON !f.bios ! INT4 !f.bios!
L2PCX -P1 -C2 ! ON ! 9600 ! ON ! COM2 ! INT3 !f.bios!
L2PCX -P1 -C2 -I7 ! ON ! 9600 ! ON ! COM2 ! INT7 !f.bios!
L2PCX -P1 -C2 -I4 -A1016 ! ON ! 9600 ! ON ! COM2 ! INT4 ! 3F8H !
L2PCX -P1 -C1 -I3 -B1200 ! ON ! 1200 ! OFF ! COM1 ! INT3 !f.bios!
L2PCX -B500 -P1 -C4 -I11 ! ON ! 9600 ! ON ! COM4 ! INT11 !f.bios!
L2PCX -xx ! OFF ! 9600 ! ON !f.bios ! INT4 !f.bios!
used CPU-time on a 80286 with connected modem und TRX (Landmark speed test):
9600bit/s -2.9MHz rx, noise, digital-squelch closed, TEST OFF 9600bit/s ca. -6MHz tx, or rx with digital-Squelch open, scrambling on. 1200bit/s -0.8Mhz
A 6MHz AT should be enough, but (especially with slow terminal software), at least a 10MHz AT should be used.
If TEST is on, besides normal operation it is also tested, if the used computer is abel to handle the occuring interrupts fast enough. At 9600 bit/s there are 4800 Interrupts/s. So interrupts mustn't be locked (mostly done by BIOS or DOS) for longer than 1/4800 secound.
The result of the test (the number of the lost interrupts) will be displayed when unloading (L2PCX -U). Every lost interrupt, which occurs while recieving or transmitting a frame will cause this frame to get lost. If frequent losses occur, e.g. during disk accesses, the computer is unlikly to be usable for packet operation with L2PCX.
Is the counter output a low number (e.g. < 50 while playing around in DOS for some minutes), it should be ok. Problems, which are not being recognized by the test, are caused by the 82C450 rs232-ic, which produces 9525 baud instead of 9600. An alternativ test for suitability for l2pcx is connecting an ear phone to the TXD line of the RS232. Distortions of the sound equally indicate frame losses during that time (don't test while the computer is idle as there losses are quite unlikely, but rather do something like typing "DIR" in DOS, or starting your terminal program). The sound CANNOT be output at the computer's internal speaker.
Testing with an terminal program, you can query the loss-counter with "esc V". To avoid that L2PCX being used on unsuitable computers, and thus user acceses being QRM'ed with too much frame losses, a "fm ERROR to nnnn" is being displayed on the Monitor channel, to remaind you about this situation. Each of this pseudo-frames means, that at this moment a frame wouldn't have been recieved, or would be sent corrupt.
Known "interrupt-killers": What to to: -------------------------------------------- EMM-driver (RAM above 1MB) Don't use it. CGA-screen with snowcheck ON Avoid the usade of snowcheck AMI-BIOS-harddisc-control try other BIOS, e.g. Award BIOS AMI-BIOS-hercules driver let terminal use direct acces to VIDEORAM some resident (TSR) programs don't load them keyboard drivers some other are better some DOS-versions the older, the better....additional information for the now available multiport-version:
starting-paramaters, an example: (see table above)
L2PCX -p1 -c1 -b9601 -p2 -c3 -b9600 -p3 -c2 -i5 -b2400 -p4 -i11 -a760 -b1202
============== ============== ================== =====================
port 1 must always be used, it is used for the L2-Timing.
Default-values: p1 = com1 from bios, int 4 9600bit/s scrambler ñ12V
p2 = com2 from bios, int 3 1200bit/s 2 x ñ12V
p3 = com3 from bios, int10 1200bit/s 2 x ñ12V
p4 = com4 from bios, int11 1200bit/s 2 x ñ12V
bitrate, scrambling,, 12V can also be changed from the terminal software. shall ports be deactivated while L2PCX is running (to avoid wasting CPU time for them), simply set them to 300 bit/s.activationg of the ports via WA8DED-hostmode:
connecting with C call portnumber (via...) e.g. C OE5XDR 3 DB0HOB
without portnumber, port 1 will be used.
transmitting UI-frames, and setting parameters:
First select Port with "PP3 T25 (set TXDelay of Port 3)
special parameters, which can't be reached in WA8DED-interface, can be
set with "P ". Take care! These values are used without
checking them.
P105 Rx buffers per link maximum (RNR)
P106 Tx buffers per link Maximum
(as WA8DED-hostmode has no data-flow-control, the host will block
when trying to send more data => Terminal will block)
P108 full duplex (only with HDLC-FIFO-interface)
P111 Passall 1/0 (crc-check off) only for monitoring
P112 Echo 1/0 (only with HDLC-FIFO-interface)
P114 transmit-port for this L2-Port
P115 (additional) recieve-Port for Multi-Rx, Baud-, Modem-Diversity
0 = port adisable in L2
P116 Digital squelch level
P117 TXWait in 10ms, delay after TX, before transmitting again.
P118 TXTail in 10ms
P121 BaudSwitchDelay in byte for mixed Baud operation (only with FIFO)
P122 Flag, Bitpatter while TXDELAY, usually: 126 (7E)
without scrambling better: 0, last flag before data always is 7E.
For 1-port-version, use these numbers minus 100 (e.g. P22 instead of P122)
