Available on: c128z c128 c64 vic20 atari atarixl to8 c64reu plus4 pc128op cpc coco3 coco

WAIT VBL

The WAIT VBL command pauses program execution until a "vertical blank" is encountered. This is a signal that is triggered at each screen refresh, which usually occurs at 50 Hz in PAL standard and 60 Hz in NTSC standard.

Some video chipsets also allow you to specify a specific raster line, so execution will continue when that specific line is reached. If the chipset does not allow this, this constraint will be ignored, while still respecting the arrival of a vertical blank.

syntax example abbreviation back to keywords

SYNTAX

 WAIT VBL [raster line]


Legend
  • id : identifier
  • type : datatype
  • v : value
  • "..." : string
  • [...] : optional

EXAMPLE

 WAIT VBL 100


ABBREVIATION: WtVb

Join BASIC 10Liner Contest with ugBASIC!

An interesting competition is held at the beginning of each year: the BASIC 10Liner Contest. It is possible to use ugBASIC to participate in the next "BASIC10Liner" competition, in the following categories:

  • PUR-120 - A game in 10 lines of max 120 characters (w/abbrev.)
  • EXTREME-256 - A game in 10 lines of max 256 characters (w/abbrev.)
  • SCHAU - Any program in 10 lines of max 256 characters (w/abbrev.)
In order to reduce space you can use this abbreviation for this instruction: 

WAIT VBL ↔ WtVb

Any problem?

If you have found a problem with this keyword, if you think there is a bug or, more simply, you would like it to be improved, open an issue for this example on GitHub.
Thank you!

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