Reference cards
|
Game controllers |
Joystick
Direction values
There are nine possible decimal values (representing 45 degree incrememts) read by each joystick register (using the STICK command in Atari BASIC), depending on the position of the stick:
Decimal Binary
14 1110
| |
10 | 6 1010 | 0110
\ |/ \ |/
11-- 15 ---7 1011-- 1111 --0111
/ |\ / |\
9 | 5 1001 | 0101
| |
13 1101
15 (1111) equals stick in the upright (neutral) position.
Memory address map
|
SHADOW REGISTER DECIMAL (HEXADECIMAL) |
HARDWARE REGISTER DECIMAL (HEXADECIMAL) |
LABEL | DESCRIPTION |
| 632 ($278) | 54016 ($D300) | STICK0 | The value of joystick 0 |
| 633 ($279) | 54017 ($D301) | STICK1 | The value of joystick 1 |
| 644 ($284) | 53264 ($D010) | STRIG0 | Stick trigger 0 |
| 645 ($285) | 53265 ($D011) | STRIG1 | Stick trigger 1 |
Paddles
Paddles are also called pots, short for potentiometer. PEEK 624 returns a number between zero and 228 ($E4), increasing as the knob is turned counter-clockwise. When used to move a player or cursor (i.e., PLOT PADDLE(0),0), test your screen first. Many sets will not display locations less than 48 ($30) or greater than 208 ($D0), and in many GRAPHICS modes you will get an ERROR 141 -- cursor out of range. Paddles are paired in the controller jacks, so paddle 0 and paddle 1 both use jack one.
Memory address map
|
SHADOW REGISTER DECIMAL (HEXADECIMAL) |
HARDWARE REGISTER DECIMAL (HEXADECIMAL) |
LABEL | DESCRIPTION |
| 624 ($270) | 53760 ($D200) | PADDL0 | The value of paddle 0 |
| 625 ($271) | 53761 ($D201) | PADDL1 | The value of paddle 1 |
| 626 ($272) | 53762 ($D202) | PADDL2 | The value of paddle 2 |
| 627 ($273) | 53763 ($D203) | PADDL3 | The value of paddle 3 |
| 628 ($274) | 53764 ($D204) | PADDL4 | The value of paddle 4 |
| 629 ($275) | 53765 ($D205) | PADDL5 | The value of paddle 5 |
| 630 ($276) | 53766 ($D206) | PADDL6 | The value of paddle 6 |
| 631 ($277) | 53767 ($D207) | PADDL7 | The value of paddle 7 |
| 636 ($27C) | 54016 ($D300) | PTRIG0 | Paddle trigger 0.
Used to determine if the trigger or button on paddle 0 is pressed (zero is returned) or not (one is returned). Since these are the same lines as the joystick left/right switches, you can use PTRIG for horizontal movement. PTRIG(1) - PTRIG(0) returns -1 (left), 0 (center), + 1 (right). |
| 637 ($27D) | 54016 ($D300) | PTRIG1 | Paddle trigger 1 |
| 638 ($27E) | 54016 ($D300) | PTRIG2 | Paddle trigger 2 |
| 639 ($27F) | 54016 ($D300) | PTRIG3 | Paddle trigger 3 |
| 640 ($280) | 54017 ($D301) | PTRIG4 | Paddle trigger 4 |
| 641 ($281) | 54017 ($D301) | PTRIG5 | Paddle trigger 5 |
| 642 ($282) | 54017 ($D301) | PTRIG6 | Paddle trigger 6 |
| 643 ($283) | 54017 ($D301) | PTRIG7 | Paddle trigger 7 |
Trakball
Thanks to George for information below on trakball functionality!
Trak-Ball has a switch for mode selection with two positions named "JS" and "TB"
- JS - emulates standard joystick
-
TB - Trak-Ball mode operates with the same bits (on addresses 632 or 633) like standard joystick, but individual bits here mean:
- bit 0 - if set to 0 then we are moving to the left, 1 = to the right
- bit 1 - repeatedly changes value while moving left or right
- bit 2 - if set to 0 then we are moving up, 1 = down
- bit 3 - repeatedly changes value while moving up or down
References
Book Mapping The Atari - Revised Edition (article Memory Map)