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Commander Keen 4 Tandy 320x200 16 color version

Eudimorphodon

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May 9, 2011
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I finally got around to trying the EGA version on my Tandy 1000HX with a VGA card, and all I can say is I'm impressed, the music is remarkably close to the Adlib soundtrack. (Considering the limitations of the 1000's audio chip.) Performancewise I think there is a slight periodic "hitching" of character animation compared to running the stock EGA version with no music, but it's very subtle; is there some kind of music cache that's being refilled? It's not enough to really be noticeable, at least on the first level.

(I honestly haven't gotten a chance to get very far into the game at all so I don't know how badly the original version slows down when there are more objects on the screen, it mostly just amazes me that it's playable on a partially-7.16mhz machine at all.)

A nice-to-have hack on the EGA versions might be to eliminate the colored border. That really tweaks out most LCD monitors, preventing them from centering the screen correctly. :p
 

Frenkel

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Jan 1, 2022
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I'm not sure if the game works on a PCjr. Does ADJMEM work on a PCjr? The game needs a lot of memory to run. Levels 1 and 15 use the most memory, level 18 the least.
Start the game as KEEN4T.EXE hard tedlevel 15 and press F10+M to see how much free memory (with purging) is left. Use KEEN4T.EXE easy tedlevel 18 to start the level that needs the least amount of memory. Disabling sound and/or music frees up some memory. When you start the game with tedlevel you need to press Ctrl+Q to quit the game, exiting the usual way will hang the system.

Press A+2+Enter to enable debug mode and then press F10+B to change the border color. 0 should disable the border / makes the border black.

The Tandy music uses code that's very similar to the Adlib music code, so I don't think that causes "hitching". Does it only happen when Tandy music is played?
 

Eudimorphodon

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Messages
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The Tandy music uses code that's very similar to the Adlib music code, so I don't think that causes "hitching". Does it only happen when Tandy music is played?

When I get a chance I'll try it again with the sound turned off and see if the behavior is the same as with it enabled.

I may also try playing it in with the CPU set to 4.77mhz to see how it'd behave in the "worst case" scenario (short of a PCjr), although an EX/HX is pretty close already. (In those machines the 256k of RAM shared with video effectively runs at 4.77mhz even in the "fast"mode, only the expansion RAM runs at full speed. Even in a machine with a VGA card like my HX the RAM timing for the top 256k is still locked at the lower speed because video read cycles continue to provide the refresh.)
 

Frenkel

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Jan 1, 2022
Messages
20
Nerdly Pleasures posted a video on YouTube showing the CGA, Tandy and EGA versions of Commander Keen 4 running on a Tandy 1000 TX.

For me it's comforting to see fading in and out in the EGA version on a Tandy 1000 is also slow, even the AdLib music slows down.

Trixter commented he's surprised to see screen tearing in the Tandy version. (There's also screen tearing in Castlevania 🤭). He says it's trivial to do page flipping. I'll have to investigate that further...
 
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