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 | _\4 | ||||
---|---|---|---|---|---|
Dec | Hex | Ctrl plus | Extra bytes | Meaning | |
0 | 0 | @ | 0 | Does nothing | |
1 | 1 | A | 1 | Sends next character to printer only | |
2 | 2 | B | 0 | Enables printer | |
3 | 3 | C | 0 | Disables printer | |
4 | 4 | D | 0 | Writes text at text cursor | |
5 | 5 | E | 0 | Writes text at graphics cursor | |
6 | 6 | F | 0 | Enables VDU driver | |
7 | 7 | G | 0 | Generates bell sound | |
8 | 8 | H | 0 | Moves cursor back one character | |
9 | 9 | I | 0 | Moves cursor forward one character | |
10 | A | J | 0 | Moves cursor down one line | |
11 | B | K | 0 | Moves cursor up one line | |
12 | C | L | 0 | Clears text window/form feed | |
13 | D | M | 0 | Carriage return (moves cursor to start of subsequent line) | |
14 | E | N | 0 | Turns on paged mode | |
15 | F | 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 |