May June 1980 - Commodore Computers

MAY/JUNE. 198O. 4.
9O 90 COMPUTE. I JUNE, 1980. ISSUE 4.
tion lion with w ith the peeked value generates simpler numbers
(shown in in the last column of the table). This
"trick" " was used in in statement 61120 6 20 in in the (he cursor
subroutine and the resulting values used in in the main
body of of the th e program.
In summary, II feel this s is is an excellent project
for a beginner. The interface is is quickly y and easily
y
put together. It It is is not difficult to 10 modify existing
programs for joystick use. "Old" " PET owners with
disappearing keytops keylOps will appreciate a the saving on
wear and tear. To T o be fair I should say that every
program ram is is not nor suitable e for conversion. When fine
control comrol of movement is is required joysticks may be
difficult to 10 use. Some players with poor hand-eye
coordination may still prefer the keyboard. As for me
It it seems quite e natural to chase and catch some seemingly
elusive demon with my movements under
reflex control by a joystick.
Chuck Johnson
JOYSTICK ATTACHMENT STANDARD
The Atari Joystick J terminates with a DB-9 connec
nnec­
tor; ; six of the nine circuits it s are used as follows:
:
DB-9PIN
FUNCTION
1 Up Switch
2
Down Switch
5435 4 3 2
1 3
Left Switch
4
Right Switch
5
Not Used
6
Push-Button Switch
98769 8 7 6 7
Not Used
8
Ground (common)
9
Not Used
Pin numbers for the DB-25P are marked on the e
connector. User Port pins are on the e bolto bottom m row of
a 12 position edge connector. Properr polarization of
th e edge connector is stro ngly recomme nded.
the edge connector is strongly recommended.
A DB-25P P connector will accept two joystick connee­
connec
IOrs tors; ; the DB-25 may then be wired 10 to a User Port
edge conneClOr connector, , according to the following table:
REFERENCES
JOYSTICK
I. 1. UUPP DOWL DOWN
LEfT LEFT
RIGHT BUTTON
GGROUND
DB-9S
J 1
2 3 4 6 8 PIN DB-25P PIN
9 10 I 11 I
12 22 24 USER PORT PIN
f F
E
D
C
Diodes to E aand f F
A
REFERENCES
1. 1. Kilobaud Microcomputing, Micl"Oco Robert W. Baker, Bakcr, January 1980.
p. t'l
p. 14
2. 2 . PET User's Group Newsletter, Vol. 0. 0, No.3. p.6, 1978
3. Best of PET Gazette, Gazelle, Chuck Johnston, , p.42, 1979
4. Cursor Magazine, P.O. Box 550, Golcta, Goicla. CA C A 93017
17
5. Dilithium Press, P.O. Box 92. 92, Forest Grove, Grove. OR O R 97116
TABLE
T = PEEK (59471)
- K (59'f71)
POSITION Joystick J 11 Joystick ick 2 T = INT(T/16)
- AND DT T
center
left h!ft right 255 223 239 255 253 254 15
13
14
up 127 247 217 7
down
wn
button buuon
It'll left lip up
righi
ght up left tiown do right down
:(ii 191 63 95
111 III 159
175 t75
251
1 243 245 246 249 250
11 II
3
5
6
9
10
mask T ORO R 15 T ORO R 240 ©
From: PET AND THE DUAL JOYSTICKS
Chuck Johnson
Note that rhat the rhe buttons are wired through diodes
to 10 both the e UPU P anda DOWN W N functions of their joysticks
(pins s E and Ff and pins K & L). When a
button n is pressed, presscd, the e PET data dara lines react as though
the e joysticks were pushed up and down n simultaneously
(an impossible conditionn for r the position switches to
generate). The decoding standard will, w , as we shall see,
interpret crpret this s condition n as a bUlIon button movement. movcme The
diodes act as "one-wayn c~way stn.;c streets" ts"
forr current fl How and
prevent the real UPU P and DOVvN DOWN switches fromm closing
both circuits.
Orientation of thee diodes is very important. t. We \lVe
want current ( to 0 now flow from Ih thee data lines to ground.
Whc Whenn soldering the diodes in placc, place, orient them with
their cathodes ("banded" ends) connecLed connected to the jjoy­
stick suttons to (pins 14 and 22 on the DB-25P).
If thee user is not interested in using g the bU buttons, ltons,
the butlOn button lines f'na mayy be Jc left rt unconnected and the
diodes
oomitted.
miucd.
JOYSTICK DB-9S PIN DB-25P PIN USER PORT PIN USER PORT FUNCTION
USER PORT FUNCTION
PA3
PA2
PA1
PAl
PAD PA0
PA2 and PA3
GROUND
2. UP 1 1 L
2. UP
DOWN 1
2 1
2 L
K
LEfT LEFT
3 3 J
RIG RIGHT HT 4 4 H
BUTTON GROUND 6 8 14 16 Diodes to K and L
N
PA7
PA6
PA5
PA4
PA6 and PA7
GROUND
PA6 and PA7