Documentation: VDU Codes (Version #21)
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VDU Codes
A table below lists the VDU codes and their meanings. Some VDU codes require parameters sending as extra bytes; e.g. VDU 22 (select screen mode) requires the screen mode passing as a parameter (one extra byte). The number of extra bytes required is also listed.
| VDU code | Ctrl plus | Extra bytes | Meaning | |
|---|---|---|---|---|
| # | # Hex | |||
| 0 | &00 | @ | 0 | Does nothing |
| 1 | &01 | A | 1 | Sends next character to printer only |
| 2 | &02 | B | 0 | Enables printer |
| 3 | &03 | C | 0 | Disables printer |
| 4 | &04 | D | 0 | Writes text at text cursor |
| 5 | &05 | E | 0 | Writes text at graphics cursor |
| 6 | &06 | F | 0 | Enables VDU driver |
| 7 | &07 | G | 0 | Generates bell sound |
| 8 | &08 | H | 0 | Moves cursor back one character |
| 9 | &09 | I | 0 | Moves cursor forward one character |
| 10 | &0A | J | 0 | Moves cursor down one line |
| 11 | &0B | K | 0 | Moves cursor up one line |
| 12 | &0C | L | 0 | Clears text window/form feed |
| 13 | &0D | M | 0 | Carriage return (moves cursor to start of subsequent line) |
| 14 | &0E | N | 0 | Turns on paged mode |
| 15 | &0F | O | 0 | Turns off paged mode |
| 16 | &10 | P | 0 | Clears graphics window |
| 17 | &11 | Q | 1 | Defines text colour |
| 18 | &12 | R | 2 | Defines graphics colour |
| 19 | &13 | S | 5 | Defines logical colour |
| 20 | &14 | T | 0 | Restores default logical colours |
| 21 | &15 | 0 | Disables VDU drivers | |
| 22 | &16 | V | 1 | Selects screen mode |
| 23 | &17 | W | 9 | Multi-purpose command: |
| 23,0 | Sets the interlace and controls cursor appearance | |||
| 23,1 | Controls text cursor appearance | |||
| 23,2-5 | Defines ECF pattern and colours | |||
| 23,6 | Sets dot-dash line style | |||
| 23,7 | Scrolls text window or screen | |||
| 23,8 | Clears a block of the text window | |||
| 23,9 | Sets first flash time | |||
| 23,10 | Sets second flash time | |||
| 23,11 | Sets default patterns | |||
| 23,12-15 | Defines simple ECF patterns and colours | |||
| 23,16 | Controls cursor movement after printing | |||
| 23,17,0-3 | Sets the tint for a colour | |||
| 23,17,4 | Chooses ECF patterns | |||
| 23,17,5 | Exchanges text foreground and background colours | |||
| 23,17,6 | Sets ECF origin | |||
| 23,17,7 | Sets character size/spacing | |||
| 23,18-24 | Reserved for future expansion | |||
| 23,25-26 | Private Font Manager calls | |||
| 23,27 | Private Sprite Manager calls | |||
| 23,28-31 | Reserved for use by application programs | |||
| 23,32-255 | Redefines printable characters | |||
| 24 | &18 | X | 8 | Defines graphics window |
| 25 | &19 | Y | 5 | PLOT command |
| 26 | &1A | Z | 0 | Restores default windows |
| 27 | &1B | [ | 0 | Does nothing |
| 28 | &1C | \ | 4 | Defines text window |
| 29 | &1D | ] | 4 | Defines graphics origin |
| 30 | &1E | ^ | 0 | Homes text cursor |
| 31 | &1F | _ | 2 | Moves text cursor |
| 127 | &7F | 0 | Delete | |
