DOS Box and OS X Screen resolutions \ VOGONS

DOS Box and OS X Screen resolutions

Topic actions

First post, by lnx64

Posted on 2013-09-18, 20:47

lnx64 Offline

Rank Newbie

Rank: Newbie
Posts: 6
Joined: 2013-09-18, 20:41

Hello, I have a Sony Trinitron VGA monitor I am going to attach to my Mac, and plan to add custom scanrates into OS X via SwitchResX (640x400@70Hz and 640x350@70Hz - both with the correct horizontal timing and front and back porch for horizontal and vertical), and was wondering if DOSBox would take advantage of those modes so when in full screen, it looked as original as possible? I know that since 320x200 graphics are already 2x the size in DOSBox, it should then fit the 640x400 frame perfectly, if DOSBox works with it.

Thanks.

Reason I ask is because when at 640x480 in DOSBox on games like Doom, there's a black bar at the top and bottom of the picture, and requires me to everytime adjust the vertical size of the monitor which is annoying.

Reply 1 of 3, by lnx64

Posted on 2013-09-20, 05:06

lnx64 Offline

Rank Newbie

Rank: Newbie
Posts: 6
Joined: 2013-09-18, 20:41

UPDATE: It worked! Sweet!

Only flaw, Jazz Jackrabbit won't trigger 640x480@60Hz, and instead triggers 640x400@70Hz. Even though the game is 320x200, on my real 486, the game runs in 480 line mode 60Hz, though drawn as 320x200.. (A odd way to do things it seems, but that's definitely what the game ran in on real hardware).

Reply 2 of 3, by ripa

Posted on 2013-09-20, 16:06

ripa Offline

Rank Oldbie

Rank: Oldbie
Posts: 559
Joined: 2005-04-18, 00:53
Location: Finland

Even though the game is 320x200, on my real 486, the game runs in 480 line mode 60Hz, though drawn as 320x200.. (A odd way to do things it seems, but that's definitely what the game ran in on real hardware).

How do you figure that?

By the way, you can get rid of the black bars at other resolutions by using aspect=true, except in text mode.

Reply 3 of 3, by lnx64

Posted on 2013-09-20, 23:24

lnx64 Offline

Rank Newbie

Rank: Newbie
Posts: 6
Joined: 2013-09-18, 20:41

ripa wrote:
Even though the game is 320x200, on my real 486, the game runs in 480 line mode 60Hz, though drawn as 320x200.. (A odd way to do things it seems, but that's definitely what the game ran in on real hardware).

How do you figure that?

By the way, you can get rid of the black bars at other resolutions by using aspect=true, except in text mode.

Scaling has some artifacts and won't look true to the original.

And I figure that because of a few things for Jazz.
1. Jazz Jackrabbit when on DOSbox in a refresh rate of 70Hz, isn't completely smooth or VSynced, but the menus are. In 60Hz the game runs nice and fluid, but the menus aren't (the menus in Jazz are regular 320x200@70Hz).

2. On my old 486 playing this game, the monitor flat out says 70Hz in the menu, and 60Hz in the game.

3. When adjusting an old IBM VGA monitor, it has two vertical size POT's inside, and they are labeled 400 line, and 480 line. 480 line controls.. 400 line POT will control also 320x200 and text mode because they are double scanned to 400 lines.. 480 line POT can also control ModeX 320x240 because that's also double scanned to 480 lines. In Jazz, the 480 line POT is in control once the game starts.. (internally according to the IBM 8512 VGA monitor service manual, the POT's are truly a 70Hz/60Hz adjustment, it doesn't really know how many lines there are, it's just about the vertical refresh rate).

Go to top of page Go to top of page

Back to DOSBox General