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A list of the VDU codes is given in the table below. Some VDU codes require extra bytes to be sent as parameters; for example, VDU 22 (select screen mode) needs one extra byte to specify the mode. The number of extra bytes needed is also given in the table:
VDU code | 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 |
10 | J | 0 | Moves cursor down one line |
11 | K | 0 | Moves cursor up one line |
12 | L | 0 | Clears text |
13 | M | 0 | |
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 |