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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 | Does nothing | ||
1 | A | 1 | Sends next character to printer only | ||
2 | B | 0 | Enables printer | ||
3 | C | 0 | Disables printer | ||
4 | D | 0 | Writes text at text cursor | ||
5 | E | 0 | Writes text at graphics cursor | ||
6 | F | 0 | Enables VDU driver | ||
7 | G | 0 | Generates bell sound | ||
8 | H | 0 | Moves cursor back one character | ||
9 | I | 0 | Moves cursor forward one character | ||
10 | J | 0 | Moves cursor down one line | ||
11 | K | 0 | Moves cursor up one line | ||
12 | L | 0 | Clears text window/form feed | ||
13 | M | 0 | Carriage return (moves cursor to start of subsequent line) | ||
14 | N | 0 | Turns on paged mode | ||
15 | O | 0 | Turns off paged mode | ||
16 | P | 0 | Clears graphics window | ||
17 | Q | 1 | Defines text colour | ||
18 | R | 2 | Defines graphics colour | ||
19 | S | 5 | Defines logical colour | ||
20 | T | 0 | Restores default logical colours | ||
21 | 0 | Disables VDU drivers | |||
22 | V | 1 | Selects screen mode | ||
23 | 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 | X | 8 | Defines graphics window | ||
25 | Y | 5 | PLOT command | ||
26 | Z | 0 | Restores default windows | ||
27 | [ | 0 | Does nothing | ||
28 | \ | 4 | Defines text window | ||
29 | ] | 4 | Defines graphics origin | ||
30 | ^ | 0 | Homes text cursor | ||
31 | _ | 2 | Moves text cursor | ||
127 | 0 | Delete |