Radio Shack TRS-80 Model III - Page 57

Transmit
=
to disable the
transmitter
=
1 to
enable the
transmitter
DTR
=
to set
Data Terminal
Ready signal
low
=
1 to set
Data Terminal
Ready signal
high
RTS
=
to set Request
to Send
signal low
=
1 to set Request
to Send
signal high
For example, to
select 7-bit
words, even parity,
two stop-bits,
transmit-enable, DTR
high and RTS
high, calculate the code
this way:
Code
=
(1*128)
+
(2*32)
+
(1*16)
+
(0*8) + (1*4) +
(1*2)
+
(!*!)
=
215
For
additional
information
on
how to determine
the
appropriate
code
characteristics,
read SRS1N1T
in the
Technical
Information Chapter
and see
Appendix I.
Wait/Don't-
Wait
Switch
The TRS-80
lets
you
choose
either Wait
or Don
'
t-Wait
serial I/O
.
When you
select
Wait I/O,
the TRS-80
will not
return from
a serial I/O
call
until the
operation
is
successful
(i.e. , a
character
is
transmitted or
received).
Pressing
(BREAK)
will
return control
to your
program.
When
you
select
Don't-Wait I/O,
the TRS-80
will
return from
a serial I/O
call
even if
the
operation
was not
successful
(i.e.
, no
character
was
transmitted or
received).
The
contents of
memory
location
16890
determines
which procedure
is used:
Contents of
16890
Procedure Used
Zero
Don't-Wait
Non-Zero
Wait
Note: To
change RS-232-C
Characteristics,
you
must do a
CALL
to SRSINIT
after
setting up
RAM
locations 1
6888-
1 6890
.
OPERATION
47