patch

[joel at oarcorp.com (joel at oarcorp.com)]

This looks like sufficient information for the BSP to at least be able to
pick the "best" console to use.  This gives a priority to the list of
choices.  The only possible missing feature is that this scheme does not
allow one to force the console to the COM port even when a video card is
present. 

--joel


On Tue, 8 Sep 1998, VALETTE Eric wrote:

> >>>>> "joel" == joel  <joel at OARcorp.com> writes:
> 
> joel> On Mon, 7 Sep 1998, VALETTE Eric wrote:
> 
> >> >>>>> "joel" == joel  <joel at OARcorp.com> writes:
> >> 
> joel> On Tue, 1 Sep 1998, Quality Quorum wrote:
> >> 
> joel> Doesn't the CMOS RAM on a standard PC have a way to determine if a video
> joel> card is present?
> >> 
> >> Probably. Note that standart BIOS just stop if they do not find the
> >> video card so it may be hard to test...
> 
> joel> What is done in more embedded PC's to avoid this?  In a normal PC, you
> joel> would always have a video card.  In an embedded PC, this must be handled.  
> joel> I assume the BIOS in the embedded PC is a bit more lenient in this regard
> joel> and continues.  Still there has to be a way for this to be represented in
> joel> the CMOS which is at worst an extension to the standard settings.
> 
> Additionnal info. May be testing the first bit is enough at 0x409 is enough :)
> 
> 
> 40:89	byte	Video display data area (MCGA and VGA)
> 
> 		?7?6?5?4?3?2?1?0? Video display data area (MCGA and VGA)
> 		 ? ? ? ? ? ? ? ??? 1=VGA is active
> 		 ? ? ? ? ? ? ???? 1=gray scale is enabled
> 		 ? ? ? ? ? ????? 1=using monochrome monitor
> 		 ? ? ? ? ?????? 1=default palette loading is disabled
> 		 ? ? ? ??????? see table below
> 		 ? ? ???????? reserved
> 		 ? ?????????  1=display switching enabled
> 		 ?????????? alphanumeric scan lines (see table below)
> 
> %		Bit7   Bit4	Scan Line information
> 		 0	0	350 line mode
> 		 0	1	400 line mode
> 		 1	0	200 line mode
> 		 1	1	reserved
> 
> 	40:8A	byte	Display Combination Code (DCC) table index (EGA+)
> 
>