Scrolling

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Demo scrolling.asm (slow animation!)

Since the year 1970 is Scrolling used in the computer technolgoy. Scrolling is a programming method to move text horizontal or vertical on the screen. Scrolling' is used in particular in video (arcade) or computer games and demos, but can also be used in all other programmes.

Kinds of Scrolling

• 

  Fort Apocalypse: multi-scrolling shooter (1982).

• 

  Zaxxon: diagonal-scrolling shooter (1984).

• 

  Lightforce: vertical-scrolling shooter (1987).

• 

  Katakis: horizontal-scrolling shooter (1988).

• 

  Turrican: multi-scrolling platformer (1990).

Technical Informations

• Horizontal (x) srolling register: 53270 (low 3 bit)
• Vertical (y) scrolling register: 53265 (low 3 bit)

Examples

BASIC

An easy BASIC example for a text scrolling demonstartion:

10 PRINT CHR$(147)
20 PRINT "SMOOTH SCROLLING TEXT"
30 FOR A=0 TO 7
40 POKE 53270,A : POKE 53265,A
50 NEXT A

Another text scrolling with color and another programming methode:
The scrolling text is in the variable LF$.

9 PRINT CHR$(147)CHR$(14): POKE 53280,PEEK(53281)
10 LF$="                                     "
11 LF$=LF$+"    * * * The C64-Wiki is fantastic ! * * *      Created by Jodigi    "
12 LF$=LF$+"    Copyright 2016        Stop with RUN/STOP key !!!             "
13 FOR X=1 TO LEN(LF$)
14 POKE 781,11:POKE 782,5:POKE 783,0:SYS 65520:PRINT MID$(LF$,X,30)
15 FOR Y=55741 TO 55770:POKE Y,X: NEXT Y,X
16 GOTO 13

Vertical scrolling

Also another scrolling methode:

0 PRINT"{clr}"
1 PRINT"{home}{down}"INT(RND(.)*100)
2 PRINT"{home}{down}{left}"CHR$(148)
3 POKE218,PEEK(218)OR128
4 GOTO1

Links

Wikipedia: Scrolling

• Scrolltexte auf codebase64.org Scrolltext programming with assembler