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First post, by darry

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Sorry if this is not the most appropriate forum, but it felt like the best place for this, since the PC is newer than the affected game .

I have a "retro" PC (Pentium 3) on which I use a mechanical USB keyboard . This usually works fine in DOS thanks to the BIOS routines for legacy keyboard emulation .

Doom, Duke Nukem 3D and others work fine under DOS too. BUT, when I tried Jazz Jackrabbit, I realized that any time a key is pressed, the animation starts to stutter . I plugged in a spare PS/2 keyboard (did not even bother unplugging the USB one), tried using it instead of the USB one and everything worked fine .

Moral of the story : PS/2 keyboard emulating BIOS code is not always perfect and having an actual PS/2 keyboard is better .

Last edited by darry on 2020-09-13, 02:50. Edited 1 time in total.

Reply 1 of 6, by darry

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darry wrote on 2020-09-13, 01:47:
Sorry if this is not the most appropriate forum, but it felt like the best place for this, since the PC is newer than the affect […]
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Sorry if this is not the most appropriate forum, but it felt like the best place for this, since the PC is newer than the affected game .

I have a "retro" PC (Pentium 3) on which I use a mechanical USB keyboard . This usually works fine in DOS thanks to the BIOS routines for legacy keyboard emulation .

Doom, Duke Nukem 3D and others work fine under DOS too. BUT, when I tried Jazz Jackrabbit, I realized that any time a key is pressed, the animation starts to stutter . I plugged in a spare PS/2 keyboard (did not even bother unplugging the USB one), tried using it instead of the USB one and everything worked fine .

Moral of the story : PS/2 keyboard emulating BIOS code is not always perfect and having an actual PS/2 keyboard is better .

Found a workaround. Using the drivers from here : http://www.bretjohnson.us/ fixed the issue completely in Jazz Jackrabbit .
All I needed to do is

a) Download and unzip http://bretjohnson.us/programs/usbdos.zip
b) Create and run a small batch file that invokes usbuhci.com and usbkeyb.com in sequence
c) Confirm that I wanted to run usbuhci.com even if I have legacy keyboard support enabled in BIOS (running usbuhci.com kills the keyboard in DOS, but running usbkeyb.com re-enables it, hence the batch file).

After that, Jazz Jackrabbit runs fine on my system with a USB keyboard .
The drivers have a rather large memory footprint, but they load high automatically if they can, which they did on my system .

EDIT: I used usbuhci.com , because my machine has a UHCI USB controller, so anyone with an OHCI USB controller would need to use usbohci.com instead .

Reply 3 of 6, by darry

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Azarien wrote on 2020-09-22, 11:10:

Maybe that keyboard can work in PS/2 mode with an adapter?

I tried the keyboard with a passive adapter, but it does not work .

An additional curiosity;running the game under Windows 98 SE results in the game giving a warning at startup, but also solves the issue with the USB keyboard . Running a DOS games under Windows in order to bypass a BIOS bug/issue is one strange workaround in my book .

Reply 4 of 6, by Shreddoc

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I found this to be one of the very few games which did not work with Bret's USB joystick drivers for DOS. Not on my machine and setup, anyway. From that, I assumed that Jazz is probably coded using some non-standard conventions for the control interface. This thread finding Jazz to be uniquely weird with a USB keyboard is further evidence supporting my vague assumption. Those Epic Megagames coders were very skilled and creative, among the top of the league at the time.

Reply 5 of 6, by BeastOfSoda

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I stumbled here because I believe I'm having the same, exact issue with Wing Commander 3. I have a Microsoft USB mouse/keyboard combo, and at first I noticed that whenever I moved the mouse, the game would freeze. Swapped RAMs, unloaded all sorts of crap, nothing.

Then after changing mainboard (to one which incidentally doesn't have USB mouse legacy support), the issue was STILL happening with keyboard only. So I briefly tested the game with my wife's PS2 keyboard (which is still her daily driver after decades of use), and lo and behold, no crash. This warrants further testing.

Reply 6 of 6, by BeastOfSoda

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Update: after some more extensive testing, I have found out that the USB keyboard is manifesting a similar problem to the OP, but only when the caps lock key is pressed (games stutter for a fraction of a second). Funny thing is, this also happens in Windows 98: if I move the mouse around and press caps lock in the meantime, the pointer will freeze briefly.

Moral of the story: no more USB keyboards and mice for me on legacy systems.