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Table A: VDU codes


List of VDU codes

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 Page
0 @ 0 Does nothing VDU 0
1 A 1 Sends next character to printer only VDU 1
2 B 0 Enables printer VDU 2
3 C 0 Disables printer VDU 3
4 D 0 Writes text at text cursor VDU 4
5 E 0 Writes text at graphics cursor VDU 5
6 F 0 Enables VDU driver VDU 6
7 G 0 Generates bell sound VDU 7
8 H 0 Moves cursor back one character VDU 8
9 I 0 Moves cursor on one space VDU 9
10 J 0 Moves cursor down one line VDU 10
11 K 0 Moves cursor up one line VDU 11
12 L 0 Clears text window VDU 12
13 M 0 Moves cursor to start of current line VDU 13
14 N 0 Turns on paged mode VDU 14
15 O 0 Turns off paged mode VDU 15
16 P 0 Clears graphics window VDU 16
17 Q 1 Defines text colour VDU 17
18 R 2 Defines graphics colour VDU 18
19 S 5 Defines logical colour VDU 19
20 T 0 Restores default logical colours VDU 20
21 U 0 Disables VDU drivers VDU 21
22 V 1 Selects screen mode VDU 22
23 W 9 Multi-purpose command: VDU 23
23,0 Sets the interlace and controls cursor appearance VDU 23,0

23,1

Controls text cursor appearance VDU 23,1

23,2-5

Defines ECF pattern and colours VDU 23,2-5

23,6

Sets dot-dash line style VDU 23,6

23,7

Scrolls text window or screen VDU 23,7

23,8

Clears a block of the text window VDU 23,8

23,9

Sets first flash time VDU 23,9

23,10

Sets second flash time VDU 23,10

23,11

Sets default patterns VDU 23,11

23,12-15

Defines simple ECF patterns and colours VDU 23,12-15

23,16

Controls cursor movement after printing VDU 23,16

23,17,0-3

Sets the tint for a colour VDU 23,17,0-3

23,17,4

Chooses ECF patterns VDU 23,17,4

23,17,5

Exchanges text foreground and background colours VDU 23,17,5

23,17,6

Sets ECF origin VDU 23,17,6

23,17,7

Sets character size/spacing VDU 23,17,7

23,18-24

Reserved for future expansion VDU 23,18-24

23,25-26

Private Font Manager calls VDU 23,25-26

23,27

Private Sprite Manager calls VDU 23,27
23,28-31 Reserved for use by application programs VDU 23,28-31
23,32-255 Redefines printable characters VDU 23,32-255
24 X 8 Defines graphics window VDU 24
25 Y 5 PLOT command VDU 25
26 Z 0 Restores default windows VDU 26
27 [ 0 Does nothing VDU 27
28 \ 4 Defines text window VDU 28
29 ] 4 Defines graphics origin VDU 29
30 ^ 0 Homes text cursor VDU 30
31 _ 2 Moves text cursor VDU 31
127 0 Delete VDU 127

This edition Copyright © 3QD Developments Ltd 2015
Last Edit: Tue,03 Nov 2015