Examples
The most fun way of getting the hang of programming is by doing. Take example programs, modify them and see what happens. Below are a number of examples, from simple to medium, which you can type into the emulator directly. For the longer ones you can also copy and past them into the emulator.
- 10 print chr$(147) ; prints control character 147 to the screen to clear the screen
- 15 print chr$(5) ; prints control character 147 to the screen change text color to white
- 20 print "hello world" ; prints the text "Hello World" on the screen
- 25 poke 53280,0 : poke 53281,0 ; changes the border and background color to 0 (black)
Exercise Change the color of the background.
A simple implementation of the snake game. There is only two rules. Don't hit anything, and survive as long as possible. Controls: Keyboard up/down ("Q"/"A"), left/right ("O"/"P"), continue ()
NOTE: Line 100 has no purpose, and is removed from the code walkthrough
- 110 print"�" ;Clear screen with special control character
- 120 fort=0to39:poke1024+t,102:next ;Poke in screen memory
- 130 fort=0to39:poke1984+t,102:next ; with checkered PETSCII character
- 140 fort=0to23:poke1024+(t*40),102:next ; to create boundary wall around the screen
- 150 fort=0to23:poke1063+(t*40),102:next
- 160 x=20:y=20:sc=0:dx=1:dy=0:sw=5:sl=sw ; init variables for position, score, x/y direction, sleep/delay timer
- 170 geta$ ; scan keyboard
- 180 ifa$="q"thendy=-1:dx=0 ; set x/y direction based on key pressed
- 190 ifa$="a"thendy=1:dx=0
- 200 ifa$="o"thendy=0:dx=-1
- 210 ifa$="p"thendy=0:dx=1
- 220 sl=sl-1:ifsl>0thengoto170 ; delay logic, control game speed
- 230 sl=sw:sc=sc+1 ; delay logic, control game speed, increase score
- 240 poke1024+x+(y*40),81 ; poke snake segment on screen (code 81)
- 250 print"";sc:sl=sl-1 ; print score + delay logic
- 260 x=x+dx:y=y+dy ; update snakepos
- 270 ad=1024+x+(y*40) ; calculate screen address of segment
- 280 ifpeek(ad)<>32thengoto300 ; if not "empty space", goto game over
- 290 goto170 ;loop
- 300 print" ** game over ** " ;game over
- 310 geta$ : ifa$<>" "thengoto310 **;check key, if not space, keep trying **
- 320 goto110 ;start game again
Basic64-JS extended commands make many things easier, then in vanilla Basic.
Here are some examples: