Fig - Free and Open Source Software

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these states are re levant and
di rect the program to calculate
a value for the va riable.
D, which represents a pa rticu
lar character found in
the string variable ca ll ed
l ST$. When a characte r
space occurs, it looks up the
appropriate item in the list
by means of the MIDS statement,
prints that c haracte r,
and resets 0 to 1. It a word
space is received, it prin ts a
space.
That's all there is to it. Because
it's simple, it's fast Inc
ide nta lly. the ?s in the li st
Program listing.
just take up spaces and also
make it like ly that an e rror
will appear as a ? in the text.
Getting it on the air: Building
th e c ircuit can be done
howe ver you w ish using
wire-wrap, point-to-po int
wiring, a un iversal prototvping
board, etc. To connec t it
to the VIC-lO, you will need
a l l l24-pin ca rd edge connecto
r, A source for this connector
is: Jameco Electronics,
1 35 5 Shorewav Ro a d ,
Be lmont CA 94002. The only
other co nnectio n re q uired is
10 POKE 37138,7
15 l ST$ = "?TEMNAIOGKDWRUS??QZYCXBJP?l,FVH" 9?8???7?
#???1-61????"? @2??3?45????"
20 A = 1: B =2:C =8: G = 67; H =48; IN= 192: M =256: S =37136
25 O=A
30 Il= IN
35 IN = PEEK(S): IF IN = Il THEN 35
40 ON (M-IN}'C GO TO 30,50,30,60,30,70,30,80
50 O =O"B:GOT0 3O
60 O =O"B:O =O+A:GOTO JO
70 IF O> G THEN O= O - H:IF O>G THEN80
75 PRINT MIO$(l STS,O,A);: GO TO 25
80 PRINT " " ;: GO TO 25
to the speaker output of the troJ is R3, the bandwidth adreceiver
or tra nsceiver. justment. It could be set a t
Adjustment is not at al l maximum bandwidth (m in icritica
l. Start out w ith all the mum re sistance) for easy
pots at ha lf rotation. Can- tuning and changed to a narnect
the side tone from an rower passband for heavy
e lectronic kever. CW ke y- QRM. The phase-locke d
boa rd, o r some other source loop in the XR-2211 does a
of accurately-spaced Morse good job of re jecting signa ls
characters to audio in. You out of its lock range. An inmay
wan t to start copying terfering signal can simply
code right off th e a ir, in be tuned off the edge of the
which c as e W1AW code passband by adjusting the
practice is an ideal source. receive r tu ning dial o r trans-
Highe r speeds are more criti- ceiver RIT. A bandpass filter
cal, so the 35-wpm practice was tried in the audio input
is best for setup. line but didn't seem to be
nece ssary.
Begin by adjusting the
tone detector. With the re- Where to go from here:
cetver tuned to match the The POKE statement in the
transmitter side to ne fr e - program leaves PBO-PB2 as
quency or whateve r pitch outputs. There is a reason
you normally use for CW, for th is, namely to al low one
adj ust R6 so th at the LED of these fines to key the
tuning ind icator (01) fl ashe s transm itte r when a se nd ing
in sync with the code be ing segme nt is added to the prore
cei ved. W ith the rec eive r gram, thereby making the
volume at normal listening VIC-20 a co m ple te CW terlevel,
turn Rl down unti l the minal . Two 73 articles
LED goes o ut then advance sho uld start you on your
It just until the light re- way to de veloping this prospends
to th e CW signa l a nd gram: " Apple, Morse, and
not background noise. It is You," AF2M, July, 1983; and
important to keep the in put "VisiCode: The VIC-20 Way
to the 2211 as low as possi- to Extra Class," W7lTH and
ble for best signa l-to-no ise KA7AQA, August, 1983_
ratio, This interface and pro-
Once the tone de tector is gram will work eq uall y well
se t up, c ha racte rs should for the Commodore 64, For
st a rt appea ring on t he the (-64 change li ne 10 to lD
screen. Adjustment of the PO KE 56579,7. In line 20,
pots on the co mpa ra to r in- c ha nge 5 = 37136 to S =
puts is best done while 56577.
listening to a good dean sig- If you would like a casnal
at machine-generated se tte copy of a comple te
code at 30 wpm o r higher. CW se nd-a nd-receive pro-
Begin by turning the dit pot gram tor the VtC-20 o r C-64
(R16) both clockwise and which features message buffcounterclockwise
until d its ers and ra ndo m code pracbegin
to be m issed, then se t tice with variable speed and
it midway between th e se c hara c t e r s pac ing, se nd
two points. Fo llow the same $6.00 to the author (this inproced
ure for R14, R17, R18, d udes postage ), Be sure to
and their re spective tunc- spec ify which computer you
tions. O nce th ese control s have.
are se t for 100% re liable Co mpute rs a re rapidly becopy
on m achine-sent code. coming a part of the ham
do not readjust them. Prob- shack, and the ea sie st place
ably you ca n find a setting for you to start is with a CW
that will copy the slo ppiest inte rfa ce . Com bining the
fist on the a ir, but accuracy o ldest form of electronic
on good code will be co m- co mm unication with the letpromised.
est in technology lends con-
The only pot you m ight tin uity to the eve r-c ha nging
want as a fro nt-panel con- hobby of amateur radio.•
73 for Radio Amateurs • April , 1986 61