Radio Shack PC-2 TRS-80 User manual

CUSTOM MANUFACTURED FOR RADIO SHACK
ADIVISION OF TANDY CORPORATION
RADIO SHACK, ADIVISION
OF TANDY CORPORATION
U.SA FORT WORTH, TEXAS 76102
CANADA: BARRIE, ONTARIO L4M 4W5
AUSTRALIA
<)1 KURRAJONG ROAD
MOUNT DRUITT N S W 2170
3A3
TANDY CORPORATION
BELGIUM
PAHC INDUSTHIEL DE NANINNE
5140 NANINNE
U K
BllSTON HOAD WEDNESBUHY
WEST MIDLANDS WSI 0 7JN
PRI~,rFD IN JAPAN

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4

SERVICE POLICY
Radio Shacl(s nationwide network of service faalitles provides qUick. convenIent.
and reliable repair services for all of
Its computer products. In most Instances
Warranty service will be performed
In accordance With RadiO Shack's Limited
Warranty. Non-warranty service will be provided
at reasonable parts and labor
costs.
Because of the sensitivity of computer equipment. and the problems which can
result from improper servICing. the followmg limitations also apply to the services
offered by Radio Shack
If any of the warranty seals on any Radio Shack computerproducts are broken.
Radio Shack reserves the right to refuse to service the eqUipment or to
VOid any
remaining warranty on the equipment.
2. If any Radio Shack computer equipment has been modified so that it IS not
within manufacturer's specifications. Including. but not limited
to, the Installation
of any non-Radio Shackparts. components, or replacement boards. then
RadiO
Shack reserves the right to refuse to service the equipment. VOid any remaining
warranty. remove and replace any non-RadiO Shack part found
In the eqUiP-
ment. and perform whatever modifications are necessary to return the eqUiP-
ment to original factory manufacturer's specificationS.
3. The cost for the labor and parts reqUired to retum the Radio Shack computer
equipment to onginal manufacturer's specifications
Will be charged to the
customer
In addition to the normal repair charge
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Introduction
Congratulations on selecting the PC-2 RS-232C Interface.
This
unit allows your PC-2 (26-3601) to communicate
with other computers and computer equipment via an
RS-232C
channel.
With this Interface, you can connect the PC-2 to and
establish data communications with:
• Computers that have RS-232C capabilities
•Modems
and Acoustic Couplers
•Printers
or plotters equipped with Serial Interfaces
This manual will:
•Describe
the RS-232C Interface.
•
Show how to connect the RS·232C Interface to your
PC-2.
•Provide
you with BASIC and Terminal commands that
let you do your own programming.
2
1/ Description of the PC-2
RS-232C Interface
Before doing anything, be sure the following accessories
are
included in the package:
RS-232 Interface
Two Metal Support Brackets
Two Long Screws to attach the Metal Support Bracket
to the Printer/Plotter/Dual Cassette Interface
AC Power
Supply Adapter
Printer/Plotter/Dual Cassette Interface Choke Cord
(For U.S.A. only)
r----';- Power
ON/OFF
Switch
L __ -~
Figure 1. PC-2 RS-232C Interface and Accessories.
(1) Power
ON/OFF Switch To turn the Interface's
power on, set this switch to the ON position. Set to
OFF to turn the power off.
3

(2) RS-232C Connector Connect one end of an appro-
priate RS-232C cable
to th is connector. Connect the
other end of the cable to the device with which you
wish to communication.
(3) PC Interface Connector Plug this connector into the
connector on the left side of the PC-2 or on the rear
panel
of the PC-2 Printer/Plotter/Dual Cassette Inter-
face.
(4) AC
Adapter To use an external power supply or to
recharge, plug the AC Adapter into the Interface
Power
Supply Jack. (See recharging instructions
before
attempting to use the PC-2 RS-232C Inter-
face.)
(5) Choke Cable. (U.S.A. only) Plug this cable into the
Printer/Plotter/Dual Cassette Interface's External
Power
Supply Jack.
(6) Metal Support Bracket A. Protects the connection
between the PC-2 and the PC-2 RS-232C Interface.
(7) Printer/Plotter/Dual Cassette Interface Metal Support
Bracket B. Protects the connection between the
Printer/Plotter/Dual Cassette Interface and the PC-2
RS-232C Interface. Requires
two screws for attach-
ment (included in the package).
4
2/ Setting-Up the PC-2 RS-232C
Interface
The PC-2 RS-232C Interface can be used with or without
a Printer/Plotter/Dual Cassette Interface. For this reason,
there are two sets of diagrams which illustrate how to
set-up the system.
Be sure to turn all equipment OFF before attempting to
connect the PC-2 RS-232C Interface.
Connecting the PC-2 to the RS-232C Interface
If you are using the PC-2 without a Printer/Plotter/Dual
Cassette Interface, follow these steps:
1. Slide Metal Support Bracket A into the slots located on
the base of the PC-2 (Figure 2).
Bracket A
Figure 2. Connecting Metal Support Bracket A
to the PC-2.
2. Remove
the Interface Covers from both the PC-2 and
the RS-232C Interface. Locate the notch on the
underside of the PC-2 and slide it into the tab of Metal
Support Bracket A.
5

3. Slide the RS-232C Interface onto Metal Support
Bracket Aso that the RS-232C 60-Pin connectors are
connected. (See Figure 3.)
Bracket B
'ii!----~ Long Screws
Figure 3. Connecting the PC-2 to the RS-232C
Interface.
4. If you are using the AC Adapter, plug it into the PC-2
RS-232C Power
Supply Jack.
Connecting the PC-2 Printer/Plotter/Dual Cassette
Interface
to the PC-2 RS-232C Interface
1. At the bottom of the PC-2 Printer/Plotter/Dual Cas-
sette Interface, remove screws A and B. Position Metal
Support Bracket Bso that the Interface cI ips to the
slot of the bracket. To secure the metal bracket, use
the long screws included with the package. (See Figure
4.)
6
Figure 4. Connecting Metal Support Bracket B to the
PC-2 Printer/Plotter/Dual Cassette Interface.
2. Slide the RS-232C Interface onto Metal Support
Bracket Bso that the Interface's male 60-Pin Plug con-
nects with
the Printer/Plotter/Dual Interface's female
60-Pin Plug. (See Figure 5.)
RS-232C
connector
Figure 5. RS·232C Interface to Printer/Plotter/Dual
Cassette Interface.
7

3. Connect one end of the RS-232C Cable to the PC-2's
RS-232C
Connector and the other end to the device
with which
you are communicating.
If you are not able to determine which cable you will
need
to connect with a particular peripheral, contact your
nearest Radio Shack Computer Center for advice.
4. (For U.S.A. only) If you are using an external power
supply for Printer/Plotter/Dual Cassette Interface,
plug
the Choke Cable into the external power supply
connector of the Printer/Plotter/Dual Cassette Inter-
face. (See Figure 6.)
Powering-Up the PC-2 RS-232C Interface
The PC-2 RS-232C Interface has abuilt-in rechargeable
battery pack available as a power source. Also, the PC-2
RS-232C Interface can also be
connected directly to an
AC Outlet via the AC Adapter included with the package.
1.
Be sure the power switch of the Interface is OFF.
2. Connect the plug of the adapter (included with this
package)
to the Interface power supply jack.
3. Plug
the Adapter into awall outlet.
When you receive the RS-232C Interface, the battery pack
is not "charged" up. Charge the batteries before using the
unit.
When
the battery pack weakens and needs to be recharg-
ed,
the Computer will tell you so by displaying one of
these messages:
The charging time will be about 15 hours.
How
to connect the AC adapter and the connecting cable.
PC-2
AC
adapter
~"-- 1"CC>l\o0l-n_n-,"t;02:~
=- ,~OOJ
printer/Plott~r/ ~ ~~
Dual Cassette J -1
1
~
Interface
Connecting ~ AC adapter
cable (( ~ - "-
Figure 6. Using the AC Adapter with the Printer/Plotter/
Dual Cassette Interface.
Connecting the Assembled Interface to aCom-
munication Device
To connect the RS-232C Interface to a communication
device (i.e., a modem or another TRS-80), you will need
an DB-25 cable such
as the Model III RS-232C Cable
(26-1408). (If
you use the PC-2 to communicate with
another TRS·80, you'll also need aNull Modem Adapter,
26-1494).
For
connection to aserial printer, use the PC·2 Serial
Printer cable (26-1327).
89

Message: Meaning:
:CHECK 8Check
the RS-232C Interface for
proper connection or possible
recharging.
NEW0?
Check the system for proper con-
nection or possible recharging.
:CHECK
68
RS-232C and Printer/Plotter/
Dual Cassette Interface battery
packs are low.
ERROR 5(,1
Low power during BASIC pro-
gramming.
LOW BATTERY
Low power during Terminal
Mode
operation.
Table 1
When
one of the above messages is displayed, recharge the
battery pack.
Using AC Power
To use the RS-232C Interface with AC power, connect
the Adapter (See "Powering-up the PC-2 RS-232C Inter-
face") and turn the power on.
Once connected to the PC-2 and powered up, the power
to the RS-232C Interface can be controlled by the
Computer.
• After turning the RS-232C's power ON, turn the PC-2
ON.
(: CHECK 8will be displayed if you don't follow
this
order.) Power is then supplied to the unit.
•When you turn the PC-2 off, the RS-232C power is also
turned OFF.
•When not using the RS-232C Interface, set the unit's
power switch to OFF.
10
3/ Using the PC-2 RS-232C
Interface
The RS-232C Interface has its own set of commands and
functions ("software") which control data communica-
tions with other devices. However, the execution of
commands and functions will not be successful unless
"hardware" is properly configured.
Specifically, this means that the input signals:
•CTS (Clear
To Send)
•CD (Carrier Detect)
•DSR (Data
Set Ready)
must all be "ready."
•Use the INSTAT command (described later) to check
the status of these signals.
•Use
the output signals commands RTS and DTR to tell
the status of Interface to the other device, are OFF at
initial power on. (See OUTSTAT.)
Important Note: The PC-2 must always be connected to
the Interface when programming with the RS-232C
commands and functions. Also, the Interface must be
connected to the PC-2 when you list or execute such
programs;
otherwise, an error message or -(tilde) will
be
displayed.
The RS-232C Interface provides extensions to PC-2
BASIC as well as a
smart terminal program in ROM.
These new
commands fall into four general categories:
•
Control statements for the RS-232C hardware. This
group allows you to configure the RS-232C hardware
and built-in terminal software for communication with
various devices.
11

• Enhancements to BASIC not related to communica-
tions. These commands are not directly related to
communications functions but they do add power and
flexibility to the existing PC-2 BASIC language.
•
Enhancements to BASIC related to communications.
This group of commands allows BASIC to interact
with external devices, utilizing the RS-232 communica-
tions hardware.
• Terminal Mode Commands. These commands allow
you to configure and control the machine-language
smart Terminal Program.
In this section, we'll describe all of the BASIC Mode
commands first. These will be listed in alphabetical order
for your convenience.
Control and Status Commands
Control and status commands provide control over various
RS-232C
protocols and configurations. All are imple-
mented as new BASIC commands.
Since the RS-232C Interface lets you control many types
of input and output devices, we'll use the following
abbreviations when referring to them. See Table 2.
KI
--
Keyboard Input
DO
--
Display Output (LCD)
PO
--
Printer Output
CI
--
Cassette Input
CO
--
Cassette Output
Table 2
12
CLOADa
Load an ASCII Format Program from RS-232C
CLOADa
CLOAOa reads an ASCII format program from the RS-
232C. This means:
•Each line must start with aline number.
•Each line is ended with acarriage return (DOH).
•
Maximum length of line is 160 characters, including
line
number and the carriage return.
•Leading blanks (after acarriage return and before a
line
number) are ignored.
•File
is ended with anull line (carriage return only).
• After compression, a maximum of 80 bytes are
allowed.
CLOAOa functions only when the cassette input is routed
from the RS-232C. Except for its characteristic of read-
ing
the program in ASCII format, it functions identically
to CLOAO.
It should be noted that the sending device must pause two
seconds between lines (after each carriage return) to allow
BASIC time to insert the new line into memory.
To load a program in ASCII format through the RS-232C,
use
the following sequence:
SETDEV CI
CLOADa
Note: A program loaded via CLOADa must not contain
the Pi symbol or the square root symbol within quoted
text.
13

CLOADr
Load Reserve Program from RS-232C
CLOADr "filename"
filename is a standard, previously assigned file
name.
CLOADr loads the set of function key definitions and
menus (a "reserve program") from the RS-232C.
CLOADr
functions only when cassette input is routed
from the RS-232C (as with SETDEV CIl.
The syntax for CLOADr is identical to that for CLOAD.
For example, to load a set of function key definitions and
menus via the RS-232C, use the following command
sequence:
SETDEV CI
CLOADr
COM$
Fetch Communications Parameters
COM$ provides a way for you to examine the current
RS-232C settings. COM$ may be used in either the RUN
or PRO Mode as a direct command or part of aprogram.
This
function returns astring of characters defining the
current RS-232C setting, in format "baud, word, parity,
stop." (This is the same format SETCOM uses to set the
parameters.)
As with
any function, COM$ must be used in conjunction
with a command (such as PR INT COM$) or variable (as
in Z$ =COM$).
14
It should be noted that COM$ always returns astring no
longer
than 16 bytes; therefore, it can be used safely
with
undimensioned string variables.
For example, if the RS-232C is currently set at 2400
Baud, 7Bit Words, Odd Parity, and 2 Stop Bits, type:
PRINT COM$ (ENTER)
and the Display will show:
2400,7,0,2
During execution of aBASIC program, reset communica-
tion parameters to 300 baud, 8 bit words, even parity,
and 2 stop bits, execute subroutine 1000, then restore to
original settings.
100 A$ =COM$
110 SETCOM 300,8, E, 2
120 GOSUB 1000
130 SETCOM A$
CONSOLE
Set End-of-Line Protocol
CONSOLE x. Y. z
xsets
the number of characters sent and is
either 0 or a number between 16 - 255.
Y. zspecifies to send acarriage return, line
feed,
or both. y, z is a combination of 0
and 1. See Table 3 for details.
CONSOLE
is used to specify the combination of line
feeds
and carriage returns transmitted as an end-of-line
symbol.
15

The general syntax for th is statement is CONSO LE x, y, z.
Both y
and zare optional, but if y or z is specified the
preceding parameter must also have been specified.
x is either 0 or 16 ~ 255, and controls the number of
characters allowed in asingle block of data sent from the
RS-232C. Acarriage return and/or line feed sequence is
automatically transmitted each x characters. If x = 0,
this automatic blocking of records is disabled.
y and zare each either 0 or 1, and each specifies either a
carriage
return (0) or line feed (1) to be sent at the end
of a data record.
If only y is specified, only one carriage return (y = 0) or
line feed (y =1) is sent at the end of a record. If y and
zare both specified, then two characters are sent as
defined by y and z, respectively.
If
y=
and
z=
,
Characters Sent
00CR
CR
01CR LF
10LF CR
11LF LF
Table 3
For example, to set maximum data line length to 80 bytes
and end-of-line protocol to carriage return only, type:
CONSOLE 80,0 (ENTER)
To set maximum data line length to no limit and end-of-
line protocol to carriage return only, type:
CONSOLE 0,0 (ENTER)
16
CSAVEa
Save Program to RS·232C in ASCII Format
CSAVEa startline, endline
startline is the first line of the program you
want to save. startline is optional; if
omitted, the first line of the program is
used.
endline is the last line of the program you
want to save. endline is optional; if omit-
ted, the last Iine of the program is used.
CSAVEa saves the current program to the RS-232C in
ASCII
format. This means:
•Each line must start with aline number.
•Each line is ended with acarriage return (ODH).
• Maximum length of line is 160 characters, including
line
number and the carriage return.
•Leading blanks (after acarriage return and before aline
number) are ignored.
•File is ended with anull line (carriage return only).
• After compression, a maximum of 80 characters are
allowed.
CSAVEa functions only when cassette output is routed to
the RS-232C.
Its
syntax is slightly different from CSAVE's, and is used
in the form CSA VEa x, y where x and yare both
optional and specify the line numbers of the first and last
lines
to be saved - just like the LLiST x, y. This lets
you save a portion of the program if desired.
Note: CSAVEa pauses two seconds between lines.
17

For example, to save the current program through the
RS-232C in ASCII format, use the following command
sequence:
SETDEV CO
CSAVEa
"PROGRAM"
CSAVEr
Send Reserve Program to RS-232C
CSAVEr
"filename"
CSAVE rsaves the current function key definitions and
menus
(a "reserve program") from the RS-232C. CSAVEr
functions only when the cassette output is routed to the
RS·232C (as with SETDEV COl.
For
example, to save the function key definitions and
menus (the "reserve
program") through the RS-232C,
use
the following command sequence:
SETDEV CO
CSAVEr
"RESRVPRG"
OEV$
Fetch Current Device Routings
DEV$
DEV$ does for the PC-2's current device setting what
COM$ does for RS-232C settings. DEV$ may be used in
either the RUN or PRO mode.
18
DEV$ returns astring of up to 14 characters listing the
names of the input devices which are currently disabled
and whose functions are being handled by the RS-232C.
It is used with the same syntax as any other function
which returns astring. For example, PRINT DEV$ and
Z$ =DEV are both valid uses.
For example, to display route settings from within a
BASIC program, use
the following string:
100 PRINT DEV$
To
route cassette input from the RS-232C without alter-
ing
any other routings, use asimilar command sequence to
the following:
100 A$ =DEV$ + ", CI"
110 SETDEV A$
To route the printer to the RS-232C, execute a subroutine
1000, then return to the original settings, use a command
sequence similar to the following:
100 A$ =DEV$
110 SETDEV PO
120 GOSUB 1000
130 SETDEV A$
ERL
Return Line Number of Error
ERL
ERL
is used with ON ERROR GOTO in error trapping.
ERL returns the line number of the statement which
caused
the current error. If an error is not present, ERL
returns O.
19

ERL has same syntax as any other function which returns
a number in that a statement or variable must be used.
For example, PRINT ERL and I= ERL are both valid
uses.
To display error and end error line numbers if errors occur
in aBASIC program, use the following sequence:
100 ON ERROR GOTO 9000
9000 PRINT "ERROR"; ERN;" IN LINE"; ERL
ERN
Return Error Code
ERN
ERN is for use in error trapping in conjunction with ON
ERROR GOTO. ERN returns the number (i.e., code) of
the current error, or 0if an error has not occurred.
ERN has the same syntax as any other function which
returns a
numeric quantity. For example, PRINT ERN
and B=ERN are
both val id uses. (See example for ER L.)
FEED
Transmit Carriage Return/Line Feed Sequences
FEED n
n is number from 1 to 65535 n is optional;
if omitted, 0 is used.
20
FEED transmits aspecified number of end-of-line
sequences (as
defined by CONSOLE). FEED interacts
with the RS-232C just as LF interacts with the printer.
For example, to transmit six end of line groups, enter:
FEED 6 (ENTER)
To list the current contents of an array A$ (10) with three
carriage return/Iinefeed groups at the end of each string,
use a
command sequence similar to the following:
100 CONSOLE 0,0, 1
110 FOR I =0 to 10
120 PRINT #-8, A$(I)
130 FEED 2
140 NEXT I
Note
that FEED 2will generate three end-of-line
sequences because
the first is automatically sent at the
end of the PR INT statement.
INPUT$
Input aString of Characters from the RS-232C
INPUT$
"prompt"; variable
prompt is the message you want displayed.
prompt is optional; if omitted, a question
mark (?) will be displayed.
variable represents
the data to be typed in.
INPUT$
is avariant of BASIC's INPUT function, differing
from
that function in two ways.
•INPUT$ requests its
data from the RS-232C, instead of
the keyboard.
21

•INPUT$ does not attempt to evaluate input as an
arithmetic expression but treats it strictly as a charac-
ter string.
INPUT$
is effective if, and only if. KI has been routed to
the RS-232C via a SETDEV command (that is, SETDEV
KI has been specified so that data requests normally filled
from the keyboard are filled from the RS-232C).
It
is used with the same general syntax as INPUT, the only
restriction being that the I NPUT$ variable must be a
string variable.
If INPUT$ has a quotated string prompt, as in INPUT$
"LOAD DATA"; A$, the prompt is handled in accord-
ance with any current display output (DO) routing.
For example, enter a command sequence similar to the
following:
100 SETDEV KI
110 INPUT$ A$
INPUT%
Fill aString Array with RS-232C Data
INPUT% "prompt"; variable
prompt is the message you want displayed.
prompt is optional; if omitted, a question
mark (7) will be displayed.
variable represents the data to the typed in and
must be a dimensioned string variable.
INPUT%
is another variant of BASIC's INPUT function.
Its sole function is to load an entire array of non-numeric
data from the RS-232C.
22
INPUT% is effective if, and only if, KI has been routed to
the RS-232C via a SETDEV command (that is, SETDEV
KI has been specified so that data requests normally filled
from the keyboard are filled from the RS-232C).
The syntax of an INPUT% statement takes the same form
as for BASIC's normal INPUT, with the single exception
that the variable must be a dimensioned string variable in
the form A$ (*).
Any prompt supplied with INPUT% is not processed
according to the current DO routing, but is always dis-
played.
When INPUT% is executed, consecutive characters receiv·
ed
from the RS-232C port are placed in consecutive array
elements in row-major order, with each array element
being filled to its maximum dimensioned length from left
to right.
INPUT%
execution stops when:
• a carriage return is received
•
the array is full.
Array
elements which are not filled during INPUT% are
nulled (set
to" H).
For example, to declare astring array Z$ as having three
rows and four columns of two-character elements, then
fill that array from RS-232C input, enter a command
sequence similar to the following:
100 DIM Z$ (4,3) *2
110 SETDEV KI
120 INPUT% "RECEIVING ARRAY"; Z$
23

As an another example, suppose that array P$ (1, 2) *3
has already been properly dimensioned, that SETDEV KI
is in effect, and that the RS-232C has been properly con-
figured via SETCOM; then, INPUT%
P$ (*) is executed.
The data string received at the RS-232C
port is
"ABCDEFGH IJLKMN".
First, all elements in array P$ are nulled, or set to " ".
NEXT, P$ (0,0) is filled from left to right with RS-232C
input characters to its maximum length (determined by
the
DIM statement which is in this case three characters).
Thus,
P$ (0,0) is set to "ABC".
Next, P$ (0, 1) is filled in the same manner. P$ (0, 1)
winds up as "DEF". Then, P$ (0, 2) is filled with "GHI".
Next, progressing through the array in row-major order,
P$ (1,0) is filled with "JKL". Then, P$ (1,1) is filled,
but since input stops at "MN", P$ (1, 1) is set equal to
"MN" and INPUT% stops.
INPUT#-8,
Input Data from the RS-232C.
INPUT #-8, "prompt"; variable
prompt is the message you want displayed.
prompt is optional; if omitted, aquestion
mark (?) will be displayed.
variable represents the data
to the typed in.
INPUT#-8, differs from INPUT only in that it requests
data
from the RS-232C instead of the keyboard. What-
ever character string
is received is evaluated in precisely
the
same manner as for INPUT (specifically including
evaluation
of arithmetic expressions). Use INPUT$ if
this expression evaluation is not desired.
24
The syntax of an INPUT#-8, statement takes exactly the
same form as BASIC's normal INPUT. If a quoted string
prompt is provided, as in INPUT#-8, "SEND DATA ";
X, the prompt is displayed in all cases.
For example, to input astring value from the RS-232C
port, use acommand similar to the following:
100 INPUT#-8, X$
To input Y from the keyboard (where the input is equal
to 0), then input Yagain from the RS-232C, use a
command sequence similar
to the following:
100 INPUT "ENTER Y "; Y
110 IF Y=0 INPUT#-8, Y
MERGEa
Merge an ASCII Format Program
MERGEa
The files to be merged must be saved with the
A
("ASCII") option.
MERGEa is to MERGE as CLOADa is to CLOAD.
MER G Ea functions only when cassette input is routed
from the RS-232C. MERGEa functions precisely the
same as does MERGE except that the PC-2 will expect
ASCII format input from the RS-232C. This means:
•Each line
must start with aline number.
•Each line
is ended with a carriage return (ODH).
•
Maximum length of line is 160 characters, including
line
number and the carriage return.
•Leading blanks (after a carriage return and before a
line number)
are ignored.
25

I
•File is ended with anull line (carriage return only).
• After compression, a maximum of 80 characters are
allowed.
To merge ASCII format program with the resident
program, through the RS-232C, use a command sequence
similar to the following:
SETDEV CI
MERGEa "PROGRAM"
INSTAT
Input Statuts
INSTAT
INST AT reads the current RS-232C status and returns it
as an integer from 0
to 31. To interpret the status, con-
vert th is integer to its binary equivalent (O's and 1's).
A 1 will mean
the line is "ready;" a 0 will mean the line
is "not ready."
This number is abinary bit image of the RS-232C's hand-
shake signal whose bits are
defined as follows:
Bit Signal
0(write) DTR (Data Terminal Ready)
1(write) RTS
(Request To Send)
2(read) CTS (Clear
To Send)
3(read) CD (Carrier Detect)
4(read) DTR (Data Terminal Ready)
5
and up
not used
26
For instance, if you type INSTAT (ENTER) and
10
appears on the Display, you should convert this number
to its binary equivalent:
00001010
Since bit counting starts at the right, Bit 0(DTR) is "not
ready," Bit 1(RTS) is "ready," Bit 2(CTS) is "not
ready," Bit 3(CD) is "ready," and Bit 4(DTR) is "not
ready."
Note that this means the device the PC-2 is communicat-
ing with should have the opposite status.
INSTAT can be used
in either R UN or PRO mode and
should be used with the same syntax as any function
which returns numeric information. For example, A=
INSTAT and PRINT INSTAT are both valid.
The following program would display whether or not a
"clear to send" status is present (bit 2 is set) during execu-
tion of aBASIC program:
100 WAIT 0
110 CLS
120 A=INSTAT
130 IF (A AND 4) =0 PRINT "NOT ";
140 WAIT
150 PRINT "CLEAR TO SEND."
27

OUTSTAT
Output Status
OUTSTAT n
n is a number from 0 to 31 whose binary bit
configuration represents the desired RS-
232C output status.
The OUTSTAT command forces a certain status to be
output at the RS-232C port. OUTSTAT may be used in
either RUN or PRO mode.
Bit Signal
0(write) DTR (Data Terminal Ready)
1(write) RTS
(Request To Send)
2(read) CTS (Clear
To Send)
3(read) CD (Carrier Detect)
4(read) DTR (Data Terminal Ready)
5
and up not used
For
example, to force output status to data terminal
ready and clear to send (set bits 0 and 4), type:
100 A = INSTAT
110 B=A OR 5
120 OUTSTAT B
PRINT#-8,
Send Data to the RS-232C
PRINT#-8,
28
PRINT#-8, differs from PRINT only in that it sends
data to the RS-232C instead of the display. Whatever list
of data is sent is formatted exactly as it would be for
PRINT.
The syntax of a PRINT#-8, statement takes exactly the
same form as BASIC's normal PRINT.
For example, to list the contents of an array U (3,2) to a
remote terminal via the RS-232C, use a command
sequence similar to the following:
100 FOR 1=0 TO 3
110FORJ=OT02
120 PRINT #-8, U(I,J)
130 NEXT J
140 NEXT I
PRINT and LPRINT Enhancements
The previously existing BASIC statements PR INT and
LPR INT are both given extra capabilities with the addi-
tion of the RS-232C accessory when their output is
routed to the RS-232C channel.
First, multiple commas may be used in one print list as
delimiters.
For example, PRINT A, B, C, D is an accept-
able
statement.
Second, with the same results as normal comma and semi-
colon statements, delimiters may be mixed randomly
within a print list. For example, LPRINT A$; B, C$; D
is an acceptable statement.
29

RINKEY$
Fetch Current Character from the RS-232C
RINKEY$
RINKEY$ is used to fetch asingle character from the RS-
232C. RINKEY$ interacts with
the RS-232C in exactly
the same way as IN KEY$ interacts with the keyboard: if
a
character is available, it is fetched as asingle character
string; otherwise null (" ") is returned.
It is used with the same syntax as any other function
which returns astring. For example, Z$ =RINKEY$ is
avalid use.
To pause run
of aBASIC program until acarriage return
(CHR$ 13) is received from the RS-232C port, use a
command sequence similar to the following:
100 A$ = RINKEY$
110 IF A$ <> CHR$ 13 THEN 100
The following short BASIC program will further demon-
strate RINKEY$. It will check the RS-232C port twice a
second and if
any character is present at the RS-232C
port, it will be displayed:
100 WAIT 32
110 A$ = RINKEY$
120 IF A$ =" " PRINT "NO CHARACTER":
GOTO 110
130
PRINT A$: GOTO 110
30
j
SETCOM
Set Communications Parameters
SETCOM
baud, word length, parity, stop bits
baud is the baud rate and is 50, 100, 110, 200,
300,600, 1200, or 2400. On power-up, 300
baud is used.
word length is the word length or number of bits
used
to transmit aword 5, 6, 7, or 8. On
power-up, 8
is used.
parity is odd, even, or none. On power-up, none
is used.
stop bits is the number of stop bits per byte
and is either 1 or 2. On power-up, 1 is used.
The SETCOM
command is used to set the RS-232C's
communications parameters -baud rate, parity, word
length, and number of stop bits. SETCOM may be used
in either the RUN or the PRO mode.
Typing SETCOM
(ENTER) resets the RS-232C to their
power-up status:
SETCOM Power-Up Status
300 Baud
8Bit Words
No Parity
1
Stop Bit
This
is the same as typing:
SETCOM 300,8, N, 1
31

I
SETCOM may be used to reset only some of the com-
munications paramters by specifying null parameters for
the settings not to be changed. For example, to change
only the parity to ODD, you could enter SETCOM, ,0
(ENTER)
To reset only the baud rate, use the command:
SETCOM 1200
To reset the baud rate to 600 and the parity to even, use
the command:
SETCOM 600" E
To change the communications parameters from within a
BASIC program,
enter:
100 INPUT "Enter new commu params "; A$
110 SETCOM A$
SETDEV
Route I/O Devices To/From the RS-232C
SETDEV device, device, ...
device is two-letter name which specifies a
PC-2 I/O device. devices are:
KI--
Keyboard Input; DO -- Display Output
(LCD); PO -- Printer Output; CI --
Cassette Input; CO -- Cassette Output
The SETDEV command is used to route the PC-2's I/O
devices
(keyboard, LCD, printer, tape) to or from the
RS-232C communication channel. SETDEV is anew
BASIC
word, and may be used in either the RUN or PRO
modes as a
direct command or as a part of aprogram.
32
Each device specified in the SETDEV command is
disabled and its input (or output) is filled from (or sent
to) the RS-232C channel.
If the command SETDEV is used alone, all device routings
are cleared
and all devices are enabled.
As an example, output from the LPR INT statement
normally is handled by the printer/plotter. If SETDEV
PO is specified, anything that would have been handled by
the printer (LPRINT, LLlST, etc.) will now be sent to the
RS-232C channel.
For example, to route all printer output to the RS-232C,
enter:
SETDEV PO (ENTER)
To route all tape input and output to (or from) the RS-
232C, enter:
SETDEV CI, CO (ENTER)
To clear all device routings, enter:
SETDEV (ENTER)
To route cassette input from the RS-232C without alter-
ing
any other routings during execution of aBASIC
program, use a command sequence similar to the
following:
100 A$ =DEV$ +", CI"
110 SETDEV A$
To route the printer to the RS-232C, execute subroutine
1000, then restore to original settings wh ile executing a
BASIC
program, use a command sequence similar to the
following:
33

100 A$ =DEV$
110 SETDEV PO
120 GOSUB 1000
130 SETDEV A$
Note: When SETDEV DO and/or SETDEV KI are in
effect, display output and keyboard input are routes only
when the PC-2 is running aprogram. They have no effect
in Immediate Mode, in which requests for keyboard input
and display are always handled normally.
SPACE$
Generate aString of ASCII Spaces
SPACE$ n
n
is a number from 0 to 31 which specifies the
number of spaces you wish to generate.
SPACE$ n
returns astring of nspaces. For example, the
string DF$="#"+SPACE$ 3+" *" would set
DF$="#~~~*"
To print fifteen spaces, type:
PRINT SPACE$ 15 (ENTER)
To print S$, then a number of spaces equal to the length
of S$, enter:
100 S=LEN S$
110 PRINT S$; SPACE$ S
34
TRANSMIT BREAK, n
Send Long Space
TRANSMIT BREAK n
n is avalue from 0 to 255 and represents n/64
of asecond. n must be specified.
TRANSM IT
BR EAK, n is used to send a "long space"
over the RS-232C.
For
example, to transmit atwo-second long space, use a
command string similar to the following:
100 TRANSMIT BREAK, 128
ZONE
Adjust Print Zone Formatting
ZONE n
nsets
the data zones and is a number from 1 to
31. If omitted, 1 is used.
ZONE
is used to modify LPRINT output when that out-
put is routed to the RS-232C (via SETDEV PO). Commas
must be used as delimiters in the list of data to be printed.
When a comma separates two items to be printed on the
PC-2 Display, the Display is spl it in half with one item
displayed
on each side. This allotts to a "zone" of 13
characters.
For
example, ZONE 10 followed by LPRINT 2, 3.45
would result in the following character sequence being
sent
to the RS-232C:
.2 3.45 (" . " represents aspace)
35