Differences

This shows you the differences between two versions of the page.

Link to this comparison view

x68000:video_ram_basics [2017/08/14 15:27]
neko68k
x68000:video_ram_basics [2019/08/27 20:45]
Line 1: Line 1:
-===== Graphic VRAM ===== 
  
- 
- The structure of G-VRAM differs depending on the actual screen size 
-and the number of colors. A total of 512 KB of VRAM is divided and 
-allocated. 
- 
-The pixel representation is a linear type and in any mode one pixel 
-is represented by one word. In the 16/256 color display mode only the 
-lower 4/8 bits are effective. 
- 
- X = X coordinate in normal mode 
- Y = Y 〃 
- P = Plane number 
- ADR = 65536 color display mode address (X,Y) 
- BIT = 〃 bit position 
- 
-**Real screen 512×512 pixels、65536 color display** 
-| Valid bits  | Full 16 bits             | 
-| 1 Row       | 1024 bytes(512 words) ​ | 
-| Page 0      | $c00000~$c7ffff ​       | 
- 
-**Real screen 512×512 pixels、256 color display:** 
-|Valid bits|Lower 8 bits| 
-|1 Row|1024 bytes(512 words)| 
-|Page 0|$c00000~$c7ffff| 
-|Page 1|$c80000~$cfffff| 
- 
- ADR = $c00000+Y×1024+X×2 
- BIT = P×8 ~ P×8+7 of 8 bits 
- 
-**Real screen 512×512 pixels、16 colors** 
-|Valid bits|Lower 4 bits| 
-|1 Row|1024 bytes(512 words)| 
-|Page 0|$c00000~$c7ffff| 
-|Page 1|$c80000~$cfffff| 
-|Page 2|$d00000~$d7ffff| 
-|Page 3|$d80000~$dfffff| 
- 
- ADR = $c00000+Y×1024+X×2 
- BIT = P×4 ~ P×4+3 of 4 bits 
- 
-**Real screen 1024×1024 pixels、16 colors:** 
-|Valid bits|Lower 4 bits| 
-|1 Row|2048 bytes(1024 words)| 
-|Page 0|$c00000~$dfffff| 
- 
- ADR = $c00000+(Y&511)×1024+(X&511)×2 
- BIT = (Y≧512)×8+(X≧512)×4 ~ 
-       (Y≧512)×8+(X≧512)×4+3 of 4 bits   ​ 
- 
-===== Text VRAM ===== 
- 
- ​T-VRAM has a real screen size of 1024x1024 pixels fixed to 16 
-color display and 4 planes for a total of 512KB. Pixel representation 
-is planar type, 1 word is 16 horizontal pixels. Each plane represents 
-1 bit of the 4-bit palette code. 
- 
-|1 Row|128 bytes(64 words)| 
-|Page 0|$e00000~$e1ffff| 
-|Page 1|$e20000~$e3ffff| 
-|Page 2|$e40000~$e5ffff| 
-|Page 3|$e60000~$e7ffff| 
 
 x68000/video_ram_basics.txt · Last modified: 2019/08/27 20:45 (external edit)
 
Except where otherwise noted, content on this wiki is licensed under the following license: CC Attribution-Noncommercial-Share Alike 4.0 International
Recent changes RSS feed Driven by DokuWiki