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VDU Variables

Programmer's Reference Manuals
» VDU Variables

VDU Variables

# Hex # Name Meaning Co-ordinates 4
0-127 &0-&7F   See Mode Variable Numbers  
         
128 &80 GWLCol Graphics Window – Lefthand Column (ic)
129 &81 GWBRow Graphics Window – Bottom Row (ic)
130 &82 GWRCol Graphics Window – Righthand Column (ic)
131 &83 GWTRow Graphics Window – Top Row (ic)
         
132 &84 TWLCol Text Window – Lefthand Column  
133 &85 TWBRow Text Window – Bottom Row  
134 &86 TWRCol Text Window – Righthand Column  
135 &87 TWTRow Text Window – Top Row  
         
136 &88 OrgX X coord of graphics Origin (ec)
137 &89 OrgY Y coord of graphics Origin (ec)
         
138 &8A GCsX Graphics Cursor X coord (ec)
139 &8B GCsY Graphics Cursor Y coord (ec)
140 &8C OlderCsX Oldest gr. Cursor X coord (ic)
141 &8D OlderCsY Oldest gr. Cursor Y coord (ic)
142 &8E OldCsX Previous gr. Cursor X coord (ic)
143 &8F OldCsY Previous gr. Cursor Y coord (ic)
144 &90 GCsIX Graphics Cursor X coord (ic)
145 &91 GCsIY Graphics Cursor Y coord (ic)
146 &92 NewPtX New point X coord (ic)
147 &93 NewPtY New point Y coord (ic)
         
148 &94 ScreenStart As used by VDU drivers  
149 &95 DisplayStart As used by display hardware  
150 &96 TotalScreenSize Memory allocated to screen  
         
151 &97 GPLFMD GCOL action for foreground col  
152 &98 GPLBMD GCOL action for background col  
153 &99 GFCOL Graphics foreground col  
154 &9A GBCOL Graphics background col  
155 &9B TForeCol Text foreground col  
156 &9C TBackCol Text background col  
157 &9D GFTint Graphics foreground tint  
158 &9E GBTint Graphics background tint  
159 &9F TFTint Text foreground tint  
160 &A0 TBTint Text background tint  
         
161 &A1 MaxMode Highest built-in numbered mode known to kernel  
         
162 &A2 GCharSizeX X size of VDU5 chars (pixels)  
163 &A3 GCharSizeY Y size of VDU5 chars (pixels)  
164 &A4 GCharSpaceX X spacing of VDU5 chars (pixels)  
165 &A5 GCharSpaceY Y spacing of VDU5 chars (pixels)  
         
166 &A6 HLineAddr Address of horizontal line-draw routine  
         
167 &A7 TCharSizeX X size of VDU4 chars (pixels)  
168 &A8 TCharSizeY Y size of VDU4 chars (pixels)  
169 &A9 TCharSpaceX X spacing of VDU4 chars (pixels)  
170 &AA TCharSpaceY Y spacing of VDU4 chars (pixels)  
         
171 &AB GcolOraEorAddr Addr of colour blocks for current GCOLs  
         
172 &AC VIDCClockSpeed VIDC clock speed in kHz3  
         
174 &AE Left border size1  
175 &AF Bottom border size1  
176 &B0 Right border size1  
177 &B1 Top border size1  
         
192 &C0 Current GraphicsV driver number2  
         
256 &100 WindowWidth Width of text window in chars  
257 &101 WindowHeight Height of text window in chars  

Notes

Unlike the Mode Variables, many of the VDU variables represent changeable properties of the video system.

1 Available from RISC OS 5.07 onwards

2 Available from RISC OS 5.21 onwards. Also available in RISC OS Select, for the current VideoV driver number.

3 Introduced in RISC OS 3, removed in RISC OS 5

4 (ic) indicates values which are stored in internal coordinates: 0,0 is the top-left pixel of the screen, with positive X pointing right and positive Y pointing down.

(ec) indicates values which are stored in external coordinates, i.e. OS units. Positive X points right, and positive Y points up. Most external coordinates are relative to the graphics origin, except the graphics origin itself (variables 136 and 137), which is a coordinate relative to the bottom-left pixel of the screen. The XEig and YEig mode variables can be used to apply the scale conversion between OS units and pixels.

See also

  • GCOL OR and EOR Address
  • Fast Horizontal Line Draw Routine
  • Mode Variable Numbers
  • OS_ReadVduVariables
Revised on August 26, 2018 11:40:21 by Jeffrey Lee (213) (86.136.230.121)
Edit | Back in time (7 revisions) | See changes | History | Views: Print | Source | Linked from: Mode Variable Numbers, Fast Horizontal Line Draw Routine, GCOL OR and EOR Address, OS_ReadVduVariables, ECF Block, OS_Byte 160 VDU Variable Numbers, OS_SpriteOp 60, OS_SpriteOp 61, Service_DisplayChanged

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