Option to change video card for systems with integrated/fixed graphics

[ruben_balea]

I don't like to have a system stuck to a video card when on the real life it can be upgraded while others like original PC can use any card available and this is not realistic, a 8088/4.77MHz IBM PC with a Diamond Stealth 3D

I'm thinking on using a single global variable (because it can't be further simplified) selected by a checkbox on config dialog, to let each machine to list compatible cards, also let video cards to load or not depending on configuration and compatibilities within them, or choosing BIOS like those cards made with 8088 code for 8 bit bus and (faster?) 286+ code for 16 bit bus. In that case if there's no 8088 BIOS don't load this card for machines with XT bus...
Here is a short example of how it may look with a 16 bit variable:

Code: Select all

some_global_var = 0 use only integrated graphics 
some_global_var > 0 add all posible video cards for each machine according to bitmask
0123456789ABCDEF 
||||||||||||||||
|||||||||||||||+- 0 PRIMARY - 1 SECONDARY *
||||||||||||||+-- 0 XT BUS  - 1 AT BUS
|||||||||||||+--- 0 MCA BUS - 1 EISA BUS
||||||||||||+---- 0 VLB BUS - 1 PCI BUS
|||||||||||+----- 0 Absent  - 1 MDA
||||||||||+------ 0 Absent  - 1 CGA
|||||||||+------- 0 Absent  - 1 Hercules
||||||||+-------- 0 Absent  - 1 AT&T/Olivetti
|||||||+--------- 0 Absent  - 1 Tandy
||||||+---------- 0 Absent  - 1 PGA
|||||+----------- 0 Absent  - 1 EGA
||||+------------ 0 Absent  - 1 VGA
|||+------------- 0 Absent  - 1 MCGA
||+-------------- 0 Absent  - 1 8514a
|+--------------- 0 Absent  - 1 XGA
+---------------- 0 Absent  - 1 SVGA and latter
* With 0 disable integrated graphics and use optional cards, with 1 keep integrated graphics and add another cards, like mixing MDA and VGA or any compatible configurations.

I do think this will be quite easy to implement, a 32 bit variable should give enough space for any video, bus or whatever standard I missed and some spare bits for other things.
I'm only giving the idea, all changes, suggestions and patches are welcome because I won't write any code, this is beyond my programming skills, sorry...

[Battler]

PCem should distinguish ISA cards from VLB/PCI cards, and make sure that non-VLB ISA systems can only accept ISA cards.