Atari CX70 User manual

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LIGHT PEN
OPERATOR'S MANUAL
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ATARI®
A Warner Communications Company 0
Model CX70
Use with
ATARI® 400™ or ATARI 800™
PERSONAL COMPUTER SYSTEMS
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ATARI
Light Pen
Operator's Manual
COPYRIGHT 1981 ATARI, Inc.
Every effort has been made to ensure that this manual
accurately documents this product of the ATARI Computer
Division. Houiever, because of the ongoing improvement and
update of the computer software and hardware, ATARI, INC.
cannot guarantee the accuracy of printed material after the
date of publication and cannot accept responsibility for
errors or omissions.
C016g67, Rev. 1

ATARI Light Pen Operator's Manual
^QNTgNTS
1. INTRODUCTION
2. POSSIBLE USES OF THE LIGHT PEN
3. CONNECTING THE LIGHT PEN
4. ATARI LIGHT PEN DEMONSTRATION PROGRAM CASSETTE
Loading Instructions
BK Version of PALLET: A Light Pen Painting Program
16K Version of PALLET
5. PROGRAMMING EXAMPLE 1: Using the Light Pen with ATARI BASIC
How Programming Example 1 Works
Experimenting with Programming Example 1
6. PROGRAMMING EXAMPLE 2
7. PROGRAMMING EXAMPLE 3
8. PROGRAMMING EXAMPLE 4
9. PERIODIC MAINTENANCE
Using PENBUF - A Light Pen Utility Program
A Keyboard Substitute
A Teaching Aid
APPENDICES
A. BASICS OF LIGHT PEN OPERATION
B. ATARI LIGHT PEN CHARACTERISTICS
C. TROUBLESHOOTING: What to Do If Your ATARI Light Pen Does Not
Respond as Expected
D. PENBUF FLOW CHART
E. PENBUF ASSEMBLY LANGUAGE LISTING
F. DESCRIPTION OF PENBUF OPERATION
G. NOTES ON MEMORY CONSERVATION/PENBUF MEMORY USAGE
H. GENERAL PROGRAMMING NOTES

ATARI Light P«n Operator's Manual
ILLUSTRATIONS
Figure Page
1 Sample Menu 3
2 Television Screen Display for 8K PALLET Program 9
3 8K Version of PALLET Program Listing 11
4 Television Screen Display for 16K PALLET 13
5 Flowchart for 16K PALLET 19
6 16K Version of PALLET Program Listing 21
7 Color Mode Numbers 23
8 Programming Example 1: Using the Light Pen with ATARI BASIC 29
9 Television Screen Display for Programming Example 1 30
10 PENBUF Loader 33
11 Programming Example 2: Using PENBUF 34
12 Programming Example 2: Modified to Run in Graphics 0 35
13 Television Screen Display for Programming Example 2 36
14 Programming Example 3: A Keyboard Substitute 37
15 Television Screen Display for Programming Example 3 38
16 Programming Example 4: A Teaching Aid 39
17 Television Screen Display for Programming Example 4 40
A. 1 Television Screen Simulation 45
A.2 Television Screen Plus Light Pen 46
D. 1 PENBUF Flow Chart 53
F. 1 Typical Insert-Sort ' 59
G. 1 PENBUF Memory Usage 62

ATARI Light Pen Operator's Manual
SECTION 1 - INTRODUCTION
The ATARI Light Pen is particularly suitable as an educational and
game playing tool as it allows the user to interact directly with the
computer. By pointing to an item on the screeni you can say "There's
the game piece I want to move<" and "There^s where I want to move it."
The most common usei howeveri is to select an item from a list or
menu> as in a multiple-choice test.
Section 2 of this manual describes menu selection and other more
sophisticated uses of the light pen. Sections 3 and 4 give
instructions for connecting the light pen to the computer and loading
the programs on the demonstration cassette. In Sections 5 through 8>
you will find several more demonstration programs to help you
understand how to write BASIC programs using the pen for your own
purposes. These examples will lead you to invent many ways to use the
light pen in your programs. In these examples* we assume you have a
working knowledge of ATARI BASIC as defined in the ATARI BASIC
Reference Manual. Although the demonstration cassette programs and all
of the programming examples in this manual are in BASIC* you may use
the pen with any of the ATARI programming languages.
General programming notes* showing the basic rules for the use of the
light pen are provided in Appendix H. Read through the manual
thoroughly first to acquaint yourself with the operating principles of
the pen. In Section 9* you will find details of the care necessary to
maintain the pen in its best operating condition.
Introduction - 1

ATARI Light Pen Operator's Manual
Introduction -> 2

ATARI Light Pen Operator's Manual
SECTION 2 - POSSIBLE USES OF THE LIGHT PEN
Menu selectionf which is a common use for the ATARI Light Pen> may
take many different forms. One form of light pen selection is
illustrated by the Keyboard Substitute programi provided as
Programming Example 3 (see Section 7). In this program^ the pen is
used to select the letter to be typed on the screen. Programming
Example 4« the Teaching Aid Program< uses the pen in two different
menus. The demonstration program provided on the cassette uses the
pen as a menu selector as well as a graphics tool.
By using the ATARI Light Pen with programs you have written^ you can
form a picturei a plot« a set of letters or groups of instructions on
the television screen. With the pen« you can point to one of those
items on the screen. The computer will read signals coming from the
pen and can interpret those signals so that it knows what action to
take next. As an example> you can produce a list of the different
progams you have available on the diskette in your ATARI Disk Drive.
The list (or menu) might appear as shown in Figure 1.
SJCt RTREK
CHECKBOOK BOEONCER
CHEC KER5
DUNGEONS OND DROGONS
PLOCE THE POINT OE THE LIGHT PEN
OGOINST THE BOH TO EOOD THE PROGROM
Figure 1 - Sample Menu
When you follow the instruction at the bottom of the television
screeni your program will sense that the switch in the tip of the
light pen is pressed and will call the light pen subroutine.
The pen can also serve as a teaching device when a student uses it
to select the correct answer from a multiple-choice set of answers
placed on the television screen. A form of this is demonstrated in
Programming Example 4, a Teaching Aid# in Section 8.
In each of these programs# items are placed at various known locations
on the screen. When the light pen registers are read# the program
compares the values obtained there to the values known to represent
Possible Uses of the Light Pen

ATARI Light Pen Operator's Manual
the position of the test characters on the screen. This information
tells the computer uhat to do next.
You may extend this control function to sense a selected menu item and
perform a complete function. Such functions may include: turning on
the Program Recorder* sounding an alarm* choosing a mathematical
formula to be executed* selecting a specific disk file* and others.
You may use the light pen as a high-speed joystick (game paddle) to
move the cursor to a neui location on the screen directly rather than
using the keyboard or paddle cursor controls. In games such as tic-
tac-toe* chess* or checkers the light pen can "pick up" a specific
item from a selected position on the game board or place that item or
a marker at another game board position.
In business app1ications* an office planner can use the light pen to
pick up a graphics-represented piece of furniture and reposition it in
another area in his graphics-represented room.
You can experiment uiith the ATARI sound generators by plotting one or
more organ keyboards on the screen. You can use the light pen to
"play" each one of the organs by selecting notes from each of the
keyboards. Each key represents one note of a selected sound generator*
and each keyboard represents a separate sound generator.
There are certain applications for uihich keyboard input would be too
complex or time-consuming. In a case like that* the computer can do
all of the work* determining the pen position and plotting items on
the screen on that basis.
A Light Pen Demonstration Program Cassette has been provided to
illustrate such an application. The cassette contains two copies of a
program called PALLET* with an 8K version on Side 1 and a 16K version
on Side 2. Each version allows you to draw with the light pen on the
screen by plotting colored dots at each position occupied by the pen.
The 16R version includes many extra features. These programs are
described in Section 4* ATARI Light Pen Demonstration Program
Cassette. These suggested uses are only a beginning. You will probably
invent many other ways to use the ATARI Light Pen in your own
programs.
Possible Uses of the Light Pen

ATARI Light Pen Operator's Manual
SECTION 3 - CONNECTING THE LIGHT PEN
The light pen connector is exactly like the
connectors. It can be inserted into any one
controller ports on the front of your ATARI
game controller
of the four game
Personal Computer System.
The demonstration
jack #1 (far left
use the pen
the pen into
in th
programs have been written
jack). Later in the manual
to look, at controller
you will be told how to
e other
controller
jacks (see Appendix H). But for nowi insert
jack #1.
Connecting the Light Pen - 5

ATARI Light Pen Operator's Manual
_ . ^
Connecting the Light Pen - 6

ATARI Light Pen Operator's Manual
SECTION 4 - ATARI LIGHT PEN DEMONSTRATION PROGRAM CASSETTE
LOADING INSTRUCTIONS ^
1. Insert an ATARI BASIC (Computing Language) cartridge into your
ATARI 400(TM) or ATARI 800<TM) computer console cartridge slot.
(Insert in the LEFT CARTRIDGE slot on the ATARI 800 computer
console. )
2. Make sure the ATARI 410(TM) Program Recorder is properly connected
to the computer console, and to a wall or power outlet. (See your
Program Recorder Operator's Manual for further details if
necessary. )
3. Turn your television set on.
4. Turn on the computer console by pressing the POWER switch on the
right side of the console to ON.
5. If all equipment is properly connected and powered up, your
television screen should be displaying the READY prompt, with the
white square "cursor" just below.
NOTE: If you have problems loading the program, and if you have other
peripherals in addition to the Program Recorder attached to the
computer console, try disconnecting the other peripherals and
connecting the Program Recorder directly to the computer console
to isolate the problem.
6. Insert Side 1 of the Light Pen Demonstration Program Cassette (8K
version) into the ATARI 410 Program Recorder. If your computer has
16K RAM or more installed, try the 16K version on Side 2 of the
cassette. Press the REWIND button on the Program Recorder to wind
the tape back to the beginning if it is not already at that
position. When the tape stops, push STOP (STOP/EJECT).
7. Type CLOAD on the computer keyboard and hit CRETURN3. The "beep"
sound is a reminder to press PLAY on the Program Recorder. Press
PLAY and hit the [RETURN] key again on the computer console.
Through the window of the Program Recorder, note that the tape is
turning. The beeps and other sounds you hear coming from the
television speaker tell you that the program is being loaded into
computer RAM.
8. When the screen displays the READY prompt again, type RUN and
press [RETURN]. The television will display the ATARI logo and the
message LOADING LIGHT PEN. You will hear another beep as the
program automatica11y begins to load into the computer. When
loading is completed, the menu will be displayed and the program
is ready for use.
ATARI Light Pen Demonstration Program Cassette

ATARI Light Pen Operator's Manual
8K VERSION OF PALLET: A Light Pen Parting Program
Once the 8K version of PALLET has been loaded< the screen uill display
a menu block draun along its right-hand edge. There are five possible
menu selections provided in this program. The top selection indicates
background color mode. If the pen is currently in this mode* any
points plotted uith the pen uill be in the background color. This has
the effect of erasing any other color uihich may have been plotted
there previously.
The next three menu choices are the color selectors. When you press
the pen against the screen at any one of these spots# the color of the
points plotted by the pen uill be in the color you selected.
The bottom menu selector is the CLEAR block. When you press the pen
against this block and lift it# the screen is cleared and
reinitialized.
To understand houf the program utorks# place the pen against the screen
somewhere near the center. A colored dot will appear if the pen is not
in the background color mode. Continue to press the tip of the pen
against the television screen and move the pen across the screen. A
line will follow the pen as it moves. This line extends from the
original spot at which the pen was placed# to the spot now occupied by
the pen. It appears to be elastic (like a rubber band) because the
line is continuously being plotted and then erased as the pen is
moved. Lift the pen from the surface. The line you have drawn is now
frozen in the last position it occupied. Draw a few more lines this
way.
ATARI Light Pen Demonstration Program Cassette - 8

ATARI Light Pen Operator's Manual
DRAWING AREA
-L
MENU
LINES PLOTTED AND
ERASED WHILE PEN
WAS PRESSED TO
SCREEN AND MOVED
AROUND
INITIAL POINT 0 TOUCHED
THIS LINE WAS
FROZEN IN PLACE
WHEN THE PEN WAS
FINALLYJ.IFTED AT
POINT 0-
1. RED BOX AS SHOWN
2. RED DOT
3. GREEN DOT
4. BLUE DOT
5. REDO
SEPARATOR BAR
FUNCTIONS: (If pen is pressed to this character)
1. Set Pen color to background ("erase" color if plotted)
2. Set Pen color to red for plotting
3. Set Pen color to green for plotting
4. Set Pen color to blue for plotting
5. Clear entire screen# redraw the menu
Figure 2 Television Screen Display for 8K PALLET Program
Press the pen against one of the other color blocks in the menu area.
Now draw one or more lines. The pen color is now the new color you
selected. Try the third color also.
When you wish to erase the screen and start over# press the pen
against the bottom box in the menu area. As it is lifted# the screen
will clear and the menu will be redrawn.
The program listing for the 8K version of PALLET is shown in Figure 3.
(Refer to Appendix G for additional notes on this program listing. ) At
this point the listing will seem somewhat cryptic# especially lines
ATARI Light Pen Demonstration Program Cassette - 9

ATARI Light Pen Operator's Manual
9000/9010. Houiever» these characters are machine language stored as
ATASCII characters to conserve space. Once you have read through
Sections 5 through 9, turn back and reread the listing. It should seem
fairly straightforward.
If you have an 8K machine* we strongly recommend that you read the
listing* the flowchart* and the description of the 16K version to
learn how much the pen can really do.
ATARI Light Pen Demonstration Program Cassette - 10

ATARI Light Pen Operator's Manual
1 REM 8K VERSION OF "PALLET"
10 REM MOD A
40 DIM A1K117) :G0SUE! 9000
45 PENC0LR=3:L0C=1536JP0KE 205,3
70 GOTO 910
80 REM MOD J
105 POKE 77,0
110 Q=INT<Y/8)
125 IF PEEK(632)=14 THEN 125
130 IF Q>=:5 AND Q08 THEN 450
135 IF 0=11 THEN 910
140 REM MOD E
150 GOSUB 2000
160 xp=xjyp«y:xi=xjyi=y
170 GOSUB 2020
190 COLOR OJPLOT XP,YPJDRAWTO XI,Y1
210 COLOR pencolr:plot XP,YPJDRAWT0 X,Y
220 X1=XJY1=Y
230 IF PEEK(632)=14 THEN 170
240 GOTO 150
449 REM MODS L,M,N,0
450 PENC0LR=Q-5;COLOR PENCOLRtGOTO 150
870 REM MOD R
910 GOSUB lOOOJGOTO 150
980 REM MOD C
1000 GRAPHICS 23:COLOR ItSETCOLOR 4,0,8
1015 SETCOLOR 0,4,14:SETCOLOR 1,12,14:SETCOLOR 2,9,14
1020 PLOT 141,0:DRAWTO 141,95
1080 PLOT 146,41IDRAWTO 146,45:DRANT0 152,45:DRAWT0 152,41tDRAWTO 146,41
PLOT 149,51.
1100 COLOR 2:PLOT 149,59
1110 COLOR 2:PL0T 149,57
1169 PLOT 150,»9Ei>R0MT0 148,89:B>RaNT0
148,93:l>RAHT0 158,93
1200 RETURN
1218 REM MOP I
200e IF PEEK16321=15 THEN 2800
2020 Q=U5RCL0C1
2040 K=PEEKC2e5>sY=PEEKC2e7)
2045 IF X<e OR V<5 OR X>159 OR V>95 TH
EN 2000
2048 IF X>140 THEN POP rGOTO 110
2050 RETURN
■ af 1P N 1 a ■ 1' < a P 'I
9010 A5tLEHCA5l-H3="31KyaZl8aiK3P''
9020 0=1535:FOR K=1 TO LEMCAlllPOKE
X,A5CCA5CX,K]1:NEXT X:RETURN
READY
Figure 3 8K Version of PALLET Program Listing
ATARI Light Pen Demonstration Program Cassette - 11

ATARI Light Pen Operator's Manual
16K Version of PALLET
Figure 4 is a television screen display for this program. A flow chart
for the program is shown in Figure and Figure 6 is the complete
program listing.
If you have already tried the 8K version of this program* you will be
able to see the additional features which this version provides*
primarily because this version assumes there is more memory available
to work with. The 8K program had only five menu choices along the
right side of the screen. This version has 12 menu choices on the
right side. Any of these choices may be selected by pressing the pen
to the screen in that area.
Of the 12 choices* the top five are known as drawing modes* the next
four are color modes and the last three are functions to be performed.
Within the blocks which define the drawing modes is a segment which
acts as an indicator bar. This indicator bar is the same color as the
border and appears at the far left edge of the selector box
representing the current drawing mode. There is another indicator bar
which appears in one of the color selector blocks. This tells you the
current color of the pen.
Among the color modes* you can select to draw in red* green* blue or
"erase" color (which sets the spot under the pen tip to the background
color). These selection modes are identical to those used in the 8K
program* however the selector blocks are larger and more clearly
defined.
In the 8K version* you only had the ability to draw in the ELASTIC
mode. Elastic refers to a line which acts like a rubber band as the
pen moves. This program provides the selection of ELASTIC mode by a
large E selector box.
ATARI Light Pen Demonstration Program Cassette - 12

ATARI Light Pen Operator's Manual
LINES DRAWN BY PEN
IN DRAW MODE
PEN PLACED HERE IN
FILL MODE, MOVED
SLOWLY TO HERE
AREA SHOWN FILLED
IN WITH SELECTED
COLOR FROM PEN TO
FIRST NON-
BACKGROUND COLOR
OCCURRING TO THE
RIGHT OF THE PEN
LOCATION
DOTS, DRAWN WITH
DOT MODE
SEPARATOR
BAR-
MENU
USER
' DRAWING MODE
■ ■
INDICATOR BAR,
MOVES BETWEEN
BOXES 1-5
ELASTIC
DRAW
GREEN
BLUE
LOAD
SAVE
CLEAR
SEGMENTS OF A LINE
DELETED WHEN PEN
PLACED HERE WHILE
COLOR MODE =
ERASE
COLOR INDICATOR
BAR MOVES BETWEEN
BOXES 6-9 TO SHOW
CURRENT COLOR
Figure 4 Television Screen for 16K PALLET Program
Functions: (Ulhen pen is pressed to this area)
filled in
block is the user programmable function
E sets the pen draining mode to ELASTIC.
F sets the pen draining mode to FILL <see Figure 4).
sets the pen draining mode to produce lines.
dot sets the Pen Draining mode to produce dots.
open square sets the pen color to background color (ERASE mode).
red square sets the pen color to red.
green square sets the pen color to green.
blue square sets the pen color to blue.
L will load a picture from diskette or cassette (change
filename in lines 710> 760).
S
CL
will save the current picture to diskette,
will erase entire screen# then redraw the menu.
ATARI Light Pen Demonstration Program Cassette ~ 13

ATARI Light Pen Operator's Manual
ELASTIC Mode
To understand how the program works< press the pen to the E block. The
drawing mode indicator bar will move into this block. Place and hold
the pen against the screen to the left of the border bar. As with the
8K version/ a line will be continuously drawn and erased from the
point of initial contact. The line will be frozen in place when you
lift the pen. The line is drawn in the color that is shown as the
current selection by the color indicator bar.
Press the pen against a different color block. The selector bar will
move into this block. The pen will now draw in the new color.
FILL Mode
The menu block beneath the E is an F selector block/ which indicates
FILL mode. After you have drawn other lines on the screen in E mode/
press the pen to the F block. The indicator bar will move into this
square.
In the FILL mode/ when the pen is pressed to the screen/ a line from
the pen to the first occurrence of a color other than the background
color/ located to the right of the current location of the pen/ will
be drawn in the currently selected color. As the pen is moved slowly
in a line/ the area between the pen and the first plotted color to the
right of the pen will be filled in with the current color.
If you lift the pen and press it to the screen elsewhere/ a line will
be drawn between the previously occupied spot and the new spot/ and
then all uncolored areas to the right of this new line will be filled
in with the current color of the pen.
NOTE; To keep this line from being drawn/ press the pen to the F
before pressing it to the drawing area again.
DOT Mode
The fifth block down from the top of the menu is the DOT mode. This
places dots in the currently chosen color under the pen. The program
takes about 1/20 second to calculate the position of the pen. If gou
draw on the screen in dot mode/ the faster you move the pen/ the
farther apart the dots will be plotted.
NOTE: The calculation time can be changed in line 40 (see Section 6).
DRAN Mode
The fourth drawing mode block/ represented by a short line/ is the
DRAM mode. It is like the DOT mode/ with a connect-the-dots function
ATARI Light Pen Demonstration Program Cassette - 14

ATARI Light Pen Operator's Manual
added to it. Try to draw on the screen in this mode. If you lift the
pen and press it to the screen elsewhere/ a line is drawn from the
last point occupied by the pen to the new position. If you wish to
prevent this interconnect line from being drawn/ press the pen to the
DRAW mode block before you press it into the drawing area again.
USER Mode
The top block in the drawing mode selector is the USER mode module.
Space in the program has been allocated for you to define your own
function. In the demonstration program/ it is defined at lines
6000-6900. Currently/ it retrieves the X and Y values of the pen and
does nothing with them. You may choose to add anything you wish to
this module/ such as plotting X and Y in a specific color.
If you have a disk drive/ you could have the user module display
a certain color in its menu block. When the pen is pressed there/
you could rotate the displayed color through the four available
colors. A certain color in this block would then specify one
of four disk files that can be used to load and save pictures.
Another possibility for the user module is using it to change the
hues and luminances of the picture. It can rotate through all
possible combinations/ or any one of many schemes you could invent.
With a little imagination/ you can find endless possibilities for
this module.
To use the user module/ the first change required to the program would
be a modification to line 1030/ which currently plots only a solid red
block in the user module space. (See Figure 6 for the program
listing. ) You may elect to plot any letter/ number/ or other figure in
this same space. The coordinates are: X between 144 and 159 inclusive/
and Y between 1 and 6 inclusive. Then in lines 6030-6900 you could do
something with the X and Y values received from <3ETP0S (maybe plot X/
Y). The last line of the user module (line 6900) is GOTO 6020
(creating an infinite loop> because while you are in any one of the
DRAW modes/ you should stay there indefinitely until the DRAW mode is
changed. Don't worry about the tracking of the modes/ the moving of
the mode bars/ range checking/ or menu selection because they have
been handled by the rest of the program (study the other modes).
ATARI Light Pen Demonstration Program Cassette - 15

ATARI Light Pen Operator's Manual
ATARI Light Pen Demonstration Program Cassette - 16