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On Apr 20, 8:24am, John H. Kim wrote:
> Subject: Re: Parallel port sound card?
> On Thu, 20 Apr 95 08:39:57 -0400 you wrote:
>
> >stop telling me I don't get sound with Doom on a 755C. I am running the
> >original shareware episode on my 755C in a DOS full window with full
> >sound.
>
> 1) I've never gotten Doom's sound (digital or music) working under DOS.
The audio support works fine on the ThinkPad 750/755C's if you have the IBM
SoundBlaster emulation TSR's running *AND* you are running a program in real-
mode. For instance, Castle Wolfenstein sounds great.
> 3) Doom's digital audio routines are broken -- it doesn't work on
> virtually all OS/2 machines, and in some DOS machines. Has anyone
> looked into a possible relationship between this and the sound
> problems Doom has on the TP? Or are they unrelated?
The sound chip that IBM chose for the 750 and 755C's is register incompatible
with the SoundBlaster OPL-1 chip. They therefore supplied a real-mode TSR
which intercepts SB interrupt requests and re-routes the call to the IBM SB
emulation routines.
Games like DOOM and Links386, and operating systems like OS/2 run in protected
mode -- they cannot access the real-mode TSR's. This does not mean that Doom's
audio routines are broken -- they are just incompatible.
If IBM ever re-wrote their SB emulators to run in protected mode, games like
Doom would run fine.
Robert
--
--
| Robert George | Army Research Laboratory |
| robertg@assb01.arl.mil | AMSRL-SS-IC |
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For in much wisdom is much grief: and he that increaseth knowledge increaseth
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