Radio Shack 26-1145 - Page 24

BAUD
Rate
#Nulls
110
None
150
None
300
None
600
None
1200
2
2400
4
4800
8
9600
16
TABLE
7. NULLS REQUIRED
AFTER return
Lower case ASCII will
be
converted
to upper
case for display (the
TRS-80
cannot
display
lower
case without
hardware
modification
[not supported
by Radio
Shack]).
Keyboard
Output to RS-232-C
The
keyboard is continually
scanned for
new key input
signals. New
key strobes
are converted
to ASCII and
outputted
to the RS-232-C
Interface for transmission.
A keyboard
entry will not cause
an
input to the
display unless the
RS-232-C output
is
echoed
back to the
input section of the
RS-232-C
port. This
is called full
duplex or FDX.
If
you short together
pins 2 and 3 on the
RS-232-C
connector, the
terminal can act in a
"local"
mode and
keyboard
action will
directly
display on the CRT.
Notice
also that such
keyboard
activity is not
stored in memory for
later
transmission,
as is sometimes
an option
with certain expensive
CRT terminals.
The Radio Shack Telephone
Modem
has
a
switch
that can be set
to
"half duplex"
(or HDX) to allow
communication
over
a
telephone
line
and
provide
(within the modem
coupler)
the echo
function which
allows the
TERM
program
to be used in HDX
situations. Most
other low speed
(300
Baud)
modems will
also
allow
this.
Special provision has
been made to allow
four
7-bit codes (selected
by the user) to be output from the
keyboard.
Refer
to Table
8.
21