There are also some games which use the refresh rate for their timing.

I just tried a new test -

I removed the old PCI-based Matrox G2+ (G200) card from my system (which used an analog 15-pin cable to connect to a fairly new 19" LG LCD), and inserted a newer AGP-based ATI 9250 card (which uses a DVI cable to connect to older 17" Sony LCD).

When I shutdown to DOS and run an old VGA game, the resolution is 1280x1024 @60Hz (as opposed to my original rig, which ran at: 720x400 @70Hz when running an old VGA game in DOS.)

The image quality now looks better IMHO. So much so, that I'm wondering whether the following purchase might be worthwhile -

Rather than invest in a bulky 20" CRT, I could get a 20" (4:3 aspect ratio) LCD instead. If this new LCD ran at its native "4:3 resolution" of 1600x1200 @ 60Hz in DOS, then would old VGA DOS games look respectable/good enough?

Thanks very much for any thoughts, best regards, Robert.

retro games 100 wrote:

"If you play an old IBM VGA game, on a CRT, you have no choice but to view it at 70Hz refresh rate. No utility exists to alter this specific refresh rate. The image onscreen also seems as if it is 640x400 resolution, but in fact it is using a "blocky-looking" graphical resolution of just 320x200."

From what I see in the NVidia vBIOS, this is true. Once the bit is set as ZERO in one of the table values that determines if a video mode is either [IBM VGA or VESA] as a VGA mode, then ONLY one of two 'dot-clock' rates are honored for that video mode, those being 25.175MHz or 28.322MHz - period. However, if that VGA/VESA bit is set as ONE for VESA mode, then all other supported 'dot-clock' rates are available. As to the "blocky-looking" resolution, in essence, the VGA mode 13h 'pixels' are double-wide and double-high due to the use of the VGA Attribute Controller (3C0h) Mode (10h) register "pixel double clock select" bit #6 and the CRTC (3C5h) Maximum Scan Line (09h) register "200-->400 Line Conversion" bit #7. We just see it as 320x200x8bpp @70Hz...

retro games 100 wrote:

"If my above paragraph is correct, then what would happen if I go and buy a 20" CRT monitor, and load-up the old DOS game "Hexen"? It would run using the IBM VGA 13h graphics mode, but visually what would I see - would the in-game image fill the whole screen, and subsequently show its "inherant 320x200 blockiness" quite noticably?"

Well, that is a bit harder to answer. The day of the VGA 320x200 mode 13h game was during the time that most monitors were CRTs and they were usually in the 14" to 15" range. The graphics were 'blocky-looking', however the smaller CRTs masked that somewhat, but hey, that was the norm for the day... Now as to how a 320x200 VGA mode 13h game would compare to that same game in a higher resolution VESA video mode on a 20" CRT today, how about an example that might give you a feel for what it might look like? A previous post of mine which has graphical examples from the Medical Level of the ORIGIN Systems' game SYSTEM SHOCK. The first example shown is at the default 320x200 pixel game resolution scaled up to 1280x800 pixels, then compared to a 'native' 😁 1280x1024 pixel resolution. The images mentioned may be found on this post. If your native Windows desktop resolution is 1280x960 or above, viewing these two images in your web-browser (completely expanded) or an image viewing utility will give you a pretty good idea of what an older VGA mode 13h game would look like 'fullscreen' on a 20"+ CRT (or LCD) running under DOS.

retro games 100 wrote:

"Rather than invest in a bulky 20" CRT, I could get a 20" (4:3 aspect ratio) LCD instead. If this new LCD ran at its native "4:3 resolution" of 1600x1200 @ 60Hz in DOS, then would old VGA DOS games look respectable/good enough?"

If this was for your main system I would probably recommend the best LCD monitor you could purchase. However, since you are looking at a retro PC for older games, I would recommend a used multi-sync 19"-21" CRT - if you can find a good one that is inexpensive. Lots of folks dumping large CRTs for new LCD monitors today. With the CRT and a good older AGP video card (say the NVidia 5950GT) you will be able to run almost every DOS VGA or DOS VESA video game ever made, looking as they were meant to be viewed. The down-side is that unless the VESA utilities mentioned can up the default refresh rate from 60Hz to say 75-85Hz the flicker will be somewhat bothersome. However, the vBIOS could be hacked to change the 'dot-clock' values... The strength of the LCD monitor is that they match up well with the default 60/70Hz output by most video adapter sold since the NVidia GF3 era. However you are at the mercy of the LCD monitor's hardware scaling for most all DOS era VGA/VESA games. Plus LCD monitors do not do black very well, at least as compared to CRT monitors.

Best of luck,

dvwjr

edit: fix text error

Very 😎 post dvwjr. Thanks.

I think it was on this forum somewhere that I spotted some positive discussion about the NVidia 5950GT. However, I decided to get the (XFX) FX 5200 version. I got it because it has a silent heatsink, and also because I didn't think that I needed all the power that the 5950GT had.

However, I don't know whether I have made the correct purchase.

Do you or anyone know - Is the only principal difference between the "mainstream cost-conscious" FX 5200 model, and the "enthusiast" 5950 model "sheer raw power"? If it is, then I think I can live without it, because I am guessing that VGA DOS and VESA DOS games don't really need something that powerful. However, if the difference is also for instance a sharper image quality and other useful things, then I would definitely consider picking up a used 5950 model on ebay.

Regarding the refresh rate on a CRT being "fixed at 70hz" for VGA DOS games, and VESA DOS games being potentially frozen at 60hz, yes that would be problem. I'll have to think about that before making any purchase decisions!

Many thanks, all the best, Robert.