Hi,

While the pattern of the graphical corruption looks very similar to memory errors if it is only happening in one game it is most likely an issue of how that game handles the display. Note that Keen Dreams was developed by ID Software to fulfil a commitment to Softdisk, so it is less well tested than the other Commander Keen games in regards of HW compatibility and it is missing the compatibility switch that Keen4 and later has in their options.

You can still do checks with programs using similar video modes, note that this game uses EGA graphics, so if you wish to do further checks you should do it with other EGA programs.

Is this Keen Dreams Shareware 1.13? Try running the game as:

1kdreams.exe detour /comp

The screen update code of Keen Dreams (and Commander Keen 4-6) has issues with some old SVGA cards mainly ones with Tseng chips. The developers have added a workaround for this (see quote by John Carmack here). On Commander Keen 4-6 this option is available in the settings menu as "SVGA compatibility" but it is probably missing in the menu of some Keen Dreams versions. It can be activated using a command line switch (/comp).

hxt59 wrote on 2026-06-21, 07:52:

Is this Keen Dreams Shareware 1.13? Try running the game as: […]
Show full quote

Is this Keen Dreams Shareware 1.13? Try running the game as:

Copy code to clipboard

1kdreams.exe detour /comp

The screen update code of Keen Dreams (and Commander Keen 4-6) has issues with some old SVGA cards mainly ones with Tseng chips. The developers have added a workaround for this (see quote by John Carmack here). On Commander Keen 4-6 this option is available in the settings menu as "SVGA compatibility" but it is probably missing in the menu of some Keen Dreams versions. It can be activated using a command line switch (/comp).

Thank you for sharing this, I was unaware of this switch, the versions of Keen Dreams I have doesn't mention this flag in the documentation, and neither have the options in the in-game menu.

MagefromAntares wrote on 2026-06-21, 09:39:

hxt59 wrote on 2026-06-21, 07:52:

Is this Keen Dreams Shareware 1.13? Try running the game as: […]
Show full quote

Is this Keen Dreams Shareware 1.13? Try running the game as:

Copy code to clipboard

1kdreams.exe detour /comp

The screen update code of Keen Dreams (and Commander Keen 4-6) has issues with some old SVGA cards mainly ones with Tseng chips. The developers have added a workaround for this (see quote by John Carmack here). On Commander Keen 4-6 this option is available in the settings menu as "SVGA compatibility" but it is probably missing in the menu of some Keen Dreams versions. It can be activated using a command line switch (/comp).

Thank you for sharing this, I was unaware of this switch, the versions of Keen Dreams I have doesn't mention this flag in the documentation, and neither have the options in the in-game menu.

You will have same issues with dangerous dave haunted mansion and others

It is a well known issue with all ET4ooo and ET6000 chips that DOS compatibility is far from perfect and they often compare badly with many competitors in this regard. Keen games are one where those chips tend to fail.
https://gona.mactar.hu/DOS_TESTS/

CharlieFoxtrot wrote on 2026-06-27, 17:09:

It is a well known issue with all ET4ooo and ET6000 chips that DOS compatibility is far from perfect and they often compare badly with many competitors in this regard. Keen games are one where those chips tend to fail.
https://gona.mactar.hu/DOS_TESTS/

For dos and isa, in my opinion nothing beats CL cards and trident

The 8900D 0WS is fastest card i ever used in DOS, faster than my ET4000, same as CL5424 but with hercules emulation, that CL cards dont have

I only recommend CL cards over trident in 286+win 3.1, the 286 trident drivers sucks

OAK cards have same problem ET cards, every realtek card i tried are slow as hell

I want to try western card, i read they are fast and compatible

theelf wrote on 2026-06-27, 19:58:

For dos and isa, in my opinion nothing beats CL cards and trident […]
Show full quote

CharlieFoxtrot wrote on 2026-06-27, 17:09:

It is a well known issue with all ET4ooo and ET6000 chips that DOS compatibility is far from perfect and they often compare badly with many competitors in this regard. Keen games are one where those chips tend to fail.
https://gona.mactar.hu/DOS_TESTS/

For dos and isa, in my opinion nothing beats CL cards and trident

The 8900D 0WS is fastest card i ever used in DOS, faster than my ET4000, same as CL5424 but with hercules emulation, that CL cards dont have

I only recommend CL cards over trident in 286+win 3.1, the 286 trident drivers sucks

OAK cards have same problem ET cards, every realtek card i tried are slow as hell

I want to try western card, i read they are fast and compatible

These Tseng Labs cards are certainly not bad, on the contrary. The issue with compatibility usually arises with games that do something little bit out of the ordinary and majority of the games work just fine (no one would’ve probably bought them back in the day, if they constantly fail to deliver working graphics). Often DOS compatibility issues get exaggerated IMO, but it is certainly worth checking it out depending on what games you want to play and if you only going to have one system for DOS.

CharlieFoxtrot wrote on 2026-06-28, 07:07:

theelf wrote on 2026-06-27, 19:58:

For dos and isa, in my opinion nothing beats CL cards and trident […]
Show full quote

CharlieFoxtrot wrote on 2026-06-27, 17:09:

It is a well known issue with all ET4ooo and ET6000 chips that DOS compatibility is far from perfect and they often compare badly with many competitors in this regard. Keen games are one where those chips tend to fail.
https://gona.mactar.hu/DOS_TESTS/

For dos and isa, in my opinion nothing beats CL cards and trident

The 8900D 0WS is fastest card i ever used in DOS, faster than my ET4000, same as CL5424 but with hercules emulation, that CL cards dont have

I only recommend CL cards over trident in 286+win 3.1, the 286 trident drivers sucks

OAK cards have same problem ET cards, every realtek card i tried are slow as hell

I want to try western card, i read they are fast and compatible

These Tseng Labs cards are certainly not bad, on the contrary. The issue with compatibility usually arises with games that do something little bit out of the ordinary and majority of the games work just fine (no one would’ve probably bought them back in the day, if they constantly fail to deliver working graphics). Often DOS compatibility issues get exaggerated IMO, but it is certainly worth checking it out depending on what games you want to play and if you only going to have one system for DOS.

What i feel with the tseng cards is "if it fail with this... what else?"

I like tseng cards, solid drivers, specially with 286, but i found trident and CL cards even faster and trouble free

Ahrle wrote on 2026-06-20, 07:29:

Just wanna check whether it's software or a potential hardware problem?

See this post on details: Re: VGA behavior when "scrolling over the edge" (and the whole thread in general).

The original EGA and VGA cards had 256KB of memory maximum. Addressing beyond this range would wrap around to zero. Mathematically this wrap lets the programmer pretend that they have a continuous 256KB window to an infinite canvas of memory.

When SVGA cards added > 256KB of VRAM, most graphics card vendors did realize (unlike to what John Carmack likes to state in interviews) that retaining the "wrap address at 256KB mark" was still important to retain behavioral compatibility.

Trident, Alliance Semi and Tseng are the three vendors that did not, and they botched their SVGA gfx card implementation: their cards would not wrap at 256KB mark, but would instead begin to address the expanded memory even in regular VGA operation modes, breaking compatibility with these VGA games.

Trident had the bug in 8800, and immediately fixed their graphics card hardware in time for launch of 8900. So did Alliance Semi.

Tseng Labs possibly may have observed that Carmack et. al. shipped a software workaround for their popular game, and did not bother to fix their hardware throughout the time that they designed new Tseng card iterations. The last sold Tseng ET6000 still has that same VGA compatibility problem that the ET3000 had.

theelf wrote on 2026-06-28, 13:24:

What i feel with the tseng cards is "if it fail with this... what else?"

I like tseng cards, solid drivers, specially with 286, but i found trident and CL cards even faster and trouble free

I have been playing a (S)VGA card bug collector/connoisseur on my graphics card test page at https://oummg.com/manual/adapters.html.

In the Tseng section I've collected together notes about Tseng's failures: https://oummg.com/manual/adapters.html#tseng

The ones I know about:
- Tseng cards fail the VGA memory wrap at 256KB mark, requiring the Commander Keen SVGA workaround.
- Tseng cards fail at setting the adapter in 8 vs 9 dot mode (controls whether text modes have an extra 9th column for VGA readability. Theirs is always forced on, IBM originally made it toggleable to enable original EGA behavior),
- Tseng cards do not support disabling the VGA cursor blink bit (to get extra background colors), but blink is always on. Result looks like this: https://oummg.com/manual/imgs/SpeedStar24_ET4000/PLASMA.png when it should look like this: https://youtu.be/ZEhANTFWbWU
- Tseng cards do not correctly decode 16-bit ISA I/O writes to address 03D5h, but only supports 8-bit ISA I/O writes to that address. This causes issues with Apogee's Crystal Caves, Secret Agent and Mike Wiering's Mario game.
- Tseng ET6000 card (I miss in my notes if I tested other Tsengs) latches the Horizontal Shift count register at noncompliant stage, at Vsync start, when original IBM VGA adapter latched it at Vsync end.
- Tseng ET6000 card has a so far unidentified pixel write bug that makes it incompatible with Jazz Jackrabbit: Jazz Multimedia G-Force 128 (Tseng ET6000) can't play Jazz Jackrabbit, https://youtu.be/Hb7zuzRKAIw

hxt59 wrote on 2026-06-21, 07:52:

Is this Keen Dreams Shareware 1.13? Try running the game as: […]
Show full quote

Is this Keen Dreams Shareware 1.13? Try running the game as:

Copy code to clipboard

1kdreams.exe detour /comp

The screen update code of Keen Dreams (and Commander Keen 4-6) has issues with some old SVGA cards mainly ones with Tseng chips. The developers have added a workaround for this (see quote by John Carmack here). On Commander Keen 4-6 this option is available in the settings menu as "SVGA compatibility" but it is probably missing in the menu of some Keen Dreams versions. It can be activated using a command line switch (/comp).

Man, thank you so much!
Relaunched the game twice and yep - works excellent every time with the detour thing 😳
Normally it's launched through START.EXE so didn't even expect kdreams.exe to work.
Thanks again! =)