中国DOS联盟

SetVESA_Mode: mov ax,0x4F02
mov bx,[VideoMode]
push ds
pop es
mov di,CRTC
int 0x10
int 0x20

VideoMode dw VESA_Mode_640x480x16M | VESA_Bit_LFB | VESA_Bit_CRTC
CRTC dw 848
dw 680
dw 744
dw 518
dw 483
dw 487
db 0
dd 52500000 ;pixel clock
dw 12000 ;120hz refresh rate
times 40 db 0

CRTCInfoBlock struc

HorizontalTotal dw ? ; Horizontal total in pixels
HorizontalSyncStart dw ? ; Horizontal sync start in pixels
HorizontalSyncEnd dw ? ; Horizontal sync end in pixels
VerticalTotal dw ? ; Vertical total in lines
VerticalSyncStart dw ? ; Vertical sync start in lines
VerticalSyncEnd dw ? ; Vertical sync end in lines
Flags db ? ; Flags (Interlaced, Double Scan etc)
PixelClock dd ? ; Pixel clock in units of Hz
RefreshRate dw ? ; Refresh rate in units of 0.01 Hz
Reserved db 40 dup (?) ; remainder of ModeInfoBlock
CRTCInfoBlock ends

我一直不清楚 水平/垂直总量、回扫时间、消隐时间 这些参数是怎么推算出来的

望大虾指点

在google输入 Generate mode timings cvt.c 可以找到

http://www.uruk.org/~erich/projects/cvt/cvt.c

电子束回扫需要时间，单位用像素计量。比所设分辨率大的数值包括回扫的时间

Thanks!

研究中

楼主写的asm有点不明白:(
VideoMode dw VESA_Mode_640x480x16M | VESA_Bit_LFB | VESA_Bit_CRTC ?
times 40 db 0 ?

对于：
CRTC dw 848
dw 680
dw 744
dw 518
dw 483
dw 487
db 0
dd 52500000 ;pixel clock
dw 12000 ;120hz refresh rate
times 40 db 0

这个是CRTCInfoBlock结构：
CRTCInfoBlock struc
HorizontalTotal dw ? ; Horizontal total in pixels
HorizontalSyncStart dw ? ; Horizontal sync start in pixels
HorizontalSyncEnd dw ? ; Horizontal sync end in pixels
VerticalTotal dw ? ; Vertical total in lines
VerticalSyncStart dw ? ; Vertical sync start in lines
VerticalSyncEnd dw ? ; Vertical sync end in lines
Flags db ? ; Flags (Interlaced, Double Scan etc)
PixelClock dd ? ; Pixel clock in units of Hz
RefreshRate dw ? ; Refresh rate in units of 0.01 Hz
Reserved db 40 dup (?) ; remainder of ModeInfoBlock
CRTCInfoBlock ends



至于
VideoMode dw VESA_Mode_640x480x16M | VESA_Bit_LFB | VESA_Bit_CRTC

这是VBE显示模式，估计这些常数是：
VESA_Mode_640x480x16M = 112h
VESA_Bit_LFB = 4000h
VESA_Bit_CRTC = 0800h


这个程序利用了VBE 3.0的一些特性：

Function 02h - Set VBE Mode

Input: AX = 4F02h Set VBE Mode
BX = Desired Mode to set
D0-D8 = Mode number
D9-D10 = Reserved (must be 0)
D11 = 0 Use current default refresh rate
= 1 Use user specified CRTC values for refresh rate
D12-13 Reserved for VBE/AF (must be 0)
D14 = 0 Use windowed frame buffer model
= 1 Use linear/flat frame buffer model
D15 = 0 Clear display memory
= 1 Don't clear display memory

ES:DI= Pointer to CRTCInfoBlock structure

Output: AX = VBE Return Status

Note: All other registers are preserved.

The CRTC information block has the following structure:

CRTCInfoBlock struc

HorizontalTotal dw ? ; Horizontal total in pixels
HorizontalSyncStart dw ? ; Horizontal sync start in pixels
HorizontalSyncEnd dw ? ; Horizontal sync end in pixels
VerticalTotal dw ? ; Vertical total in lines
VerticalSyncStart dw ? ; Vertical sync start in lines
VerticalSyncEnd dw ? ; Vertical sync end in lines
Flags db ? ; Flags (Interlaced, Double Scan etc)
PixelClock dd ? ; Pixel clock in units of Hz
RefreshRate dw ? ; Refresh rate in units of 0.01 Hz
Reserved db 40 dup (?) ; remainder of ModeInfoBlock
CRTCInfoBlock ends


The Flags field defines the following flags that modify the operation of the mode as follows:


D0 = Double Scan Mode Enable
0 = Graphics mode is not double scanned
1 = Graphics mode is double scanned
D1 = Interlaced Mode Enable
0 = Graphics mode is non-interlaced
1 = Graphics mode is interlaced
D2 = Horizontal sync polarity
0 = Horizontal sync polarity is positive (+)
1 = Horizontal sync polarity is negative (-)
D3 = Vertical sync polarity
0 = Vertical sync polarity is positive (+)
1 = Vertical sync polarity is negative (-)

VBE 3.0:
http://www.vesa.org/public/VBE/vbe3.pdf

我用了自己的编译器的语法
times 40 db 0 就是 40 个字节的0