[TC] How to use color constant ( >=8 ) as background color ? - MS-DOS

Dear all,

In Turbo C, using textbackground( color ) can set the color of
background. But color is ranging from 0( black ) to 7 ( lightgray
)...few choices...

Does anyone know how to use color constant which is [8~15] as
background color ? Do I need to change the video mode ? ( Now I used
80x25 text mode, which is mode "3"...)

Thanks in advance ^_^

jimmyliao

On 4 Jul 2006 04:52:03 -0700, "liaoo" wrote:

>In Turbo C, using textbackground( color ) can set the color of
>background. But color is ranging from 0( black ) to 7 ( lightgray
>)...few choices...
>
>Does anyone know how to use color constant which is [8~15] as
>background color ? Do I need to change the video mode ? ( Now I used
>80x25 text mode, which is mode "3"...)

There is a BIOS call that lets you do this, but you lose the "blink"
attribute in trade. The call is INT 10 AX=1003, but I don't know if TC
implements it in a library function.

-Scott

Scott 寫道：

> There is a BIOS call that lets you do this, but you lose the "blink"
> attribute in trade. The call is INT 10 AX=1003, but I don't know if TC
> implements it in a library function.
>
> -Scott

Thanks ! I think I can use inline assembly to "create" such function,
right ?

liaoo wrote:
> Scott 寫道：
>
>
>>There is a BIOS call that lets you do this, but you lose the "blink"
>>attribute in trade. The call is INT 10 AX=1003, but I don't know if TC
>>implements it in a library function.
>>
>>-Scott
>
>
> Thanks ! I think I can use inline assembly to "create" such function,
> right ?
>
int 10h
ah=10h
al=3
bl=0 for background colours, 1 for blink

See int86() in the runtime library. int86() can be used to call
interrupts from C.


Alex

Dear all,

I found the following phenomenon and wonder whether anyone knows why :

------------------------------------------------------------------------------------------------------------
step1 : set background color to A ( A is color constant > 7, Ex. 8 )
by above method

step2 : access directly video memory with background color B
( Ex. B = 2 )

step3 : write video memory with background color A
------------------------------------------------------------------------------------------------------------

The output is :

-----------------------------------------------
after step2, I saw color "B"
after step3, I saw color "A"
-----------------------------------------------

Thus can I inference that only BOTH "set palette" and "directly access
attribute byte" can change to the desired background color "which is >
7" ?

( For background color <=7, just access attribute byte is enough....)

liaoo 寫道：

> Dear all,
>
> I found the following phenomenon and wonder whether anyone knows why :
>
> ------------------------------------------------------------------------------------------------------------
> step1 : set background color to A ( A is color constant > 7, Ex. 8 )
> by above method
>
> step2 : access directly video memory with background color B
> ( Ex. B = 2 )
>
> step3 : write video memory with background color A
> ------------------------------------------------------------------------------------------------------------
>
> The output is :
>
> -----------------------------------------------
> after step2, I saw color "B"
> after step3, I saw color "A"
> -----------------------------------------------
>
> Thus can I inference that only BOTH "set palette" and "directly access
> attribute byte" can change to the desired background color "which is >
> 7" ?
>
> ( For background color <=7, just access attribute byte is enough....)

After testing, I used the following rule to config background color:

--------------------------------------------------------------------------------------------------------------
if( color > 7 and color < 16 )
then set video palette by INT 10h ( ah = 10h, al = 03h, bl = 0h, bh=
color )

write directly to video memory with bit[7:4] of attribute byte = color
--------------------------------------------------------------------------------------------------------------

Is above a correct programming method ?

Regards,
jimmyliao