True CGA vs VGA card in CGA mode

[QuantumII]

Hi all

Is there any performance differences between a true CGA card and a 8-bit VGA card running CGA graphics ?

[per]

If it has switches so it oculd be toggeled to CGA mode on startup, it would operate as a CGA, and there would be no differences unless the card is of lower quality and price.

However, if it's configured as VGA on startup, it might have some problems with certain CGA graphics modes.

[patscc]

Well, they typically live at different addresses in the pc's address space.
0A0000-0AFFFF VGA/EGA Video Memory
0B0000-0B0FFF Monochrome Video Memory
0B8000-0BFFFF CGA

patscc

[QuantumII]

Well, they typically live at different addresses in the pc's address space.
0A0000-0AFFFF VGA/EGA Video Memory
0B0000-0B0FFF Monochrome Video Memory
0B8000-0BFFFF CGA

patscc

Okay. I was thinking more along the line: If I run a game in CGA on a VGA card or run it on a true CGA card, will there be any noticeable performance differences ?

I talk simple games, like Alley Cat

[per]

Okay. I was thinking more along the line: If I run a game in CGA on a VGA card or run it on a true CGA card, will there be any noticeable performance differences ?

I talk simple games, like Alley Cat

I have had some problems with that. Often, the VGA is toggeled into wrong video modes, ant it doesn't really support some of the special modes of the CGA, like some of the CGA's graphics mode, like morecolors and the BG/red/cyan/white palette.

See the attachement of running Flightsimulator 2.13 (Booter) on a VGA in VGA mode and VGA in CGA mode. Note that "Signal Error" alert in the upper right courner on one of the pictures, hence, NOT recomended on CRT monitors.

[Fallo]

I have had some problems with that. Often, the VGA is toggeled into wrong video modes, ant it doesn't really support some of the special modes of the CGA, like some of the CGA's graphics mode, like morecolors and the BG/red/cyan/white palette.

See the attachement of running Flightsimulator 2.13 (Booter) on a VGA in VGA mode and VGA in CGA mode. Note that "Signal Error" alert in the upper right courner on one of the pictures, hence, NOT recomended on CRT monitors.

Galaxian is one game I know that does this. It works on some VGA monitors, but on others the picture loses sync.

Moon Patrol always locks up about 7 seconds into the game (Demonlord noted this on his site). Both of these games have some kind of problem with VGA, but I'm not sure what.

VGA is BIOS compatible with CGA, but not register compatible. At least 60% of CGA software works on VGA, but the other 30% either partially or completely fails. This can be caused by any of the following:

*Setting video modes or color palettes by writing directly to the registers

*Using the 160x100 pseudographics mode

*Raster interrupts

*Tweaking the 6845 registers to produce effects like screen shaking

[QuantumII]

I have had some problems with that. Often, the VGA is toggeled into wrong video modes, ant it doesn't really support some of the special modes of the CGA, like some of the CGA's graphics mode, like morecolors and the BG/red/cyan/white palette.

See the attachement of running Flightsimulator 2.13 (Booter) on a VGA in VGA mode and VGA in CGA mode. Note that "Signal Error" alert in the upper right courner on one of the pictures, hence, NOT recomended on CRT monitors.

Yeah, I tried FS on VGA, and it was just like your picture.. Say, did you boot the game from a floppy or did you run the fs.com file ?

[per]

Yeah, I tried FS on VGA, and it was just like your picture.. Say, did you boot the game from a floppy or did you run the fs.com file ?

I booted from a floppy (from retrogade, that one got no hidden message on it).

You say you got a CGA with a RCA jack. If you got a monitor/TV capable of displaying NTSC, you could connect it to the CGA. FS is a lot better in composite than RGBI.

[Chuck(G)]

How about a CGA with a scan converter box (as discussed on other threads?). I assume the idea is to use a VGA monitor.

[QuantumII]

How about a CGA with a scan converter box (as discussed on other threads?). I assume the idea is to use a VGA monitor.

Yes, if I cannot get a CGA monitor within reasonable time (I'm an impatient guy sometimes) I'll get one of those.. They could be nice to have anyway