Tomb Raider without FPU? \ VOGONS

Tomb Raider without FPU?

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First post, by kool kitty89

Posted on 2012-07-13, 06:21

kool kitty89 Offline

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Does anyone know if DOS Tomb Raider can run on a CPU lacking an FPU (ie 386 sans 387, or 486SX)? I read an anecdote a while back about getting TR running on a 386-20 (very slow, but functional), but it wasn't mentioned whether a 387 was installed. (at the time, I'd assumed it wasn't since 386 systems rarely had them, and I think there was some mention of quake nor working either)

It would be really interesting to find this out as it would make TR the most advanced/intensive commertial PC game to work with integer (or fixed-point) computation alone. (of course, the Saturn, Playstation, and several early/mid 90s arcade boards also made do without FPUs, though they also had exceptional integer computational resources -SH2s in the Saturn with very fast 32-bit multiplier, DSPs in arcade boards, GTE in PSX)

Reply 1 of 4, by SarahWalker

Posted on 2012-07-13, 08:20

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IIRC Tomb Raider makes fairly heavy use of FP.

Reply 2 of 4, by elianda

Posted on 2012-07-13, 11:46

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Well for a proof of principle this doesn't matter.

So to check if Tomb Raider uses FPU run a debug version of the dosbox emulator and dump the disassembled opcodes to a file. Then check for FPU instructions.

For a 386 you can install a TSR that hooks illegal instruction exceptions and executes FPU instructions by integer emulation. This is of course several orders of magnitudes slwoer than a real FPU. Or you might do this in a Win 3.x dos window.

Or run Tomb Raider in the Dosbox Emulator on a 386 under Win95.

Still every attempt would be just a proof of principle...

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Reply 3 of 4, by leileilol

Posted on 2012-07-13, 15:55

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You could try running Tomb Raider on PCem using any "SX" processor in there.

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Reply 4 of 4, by Garrett W

Posted on 2021-03-13, 13:19

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Massive bump, but I stumbled upon this thread a while ago and decided to give it a try. So for the sake of posterity, Tomb Raider runs on my TX486DLC (Cyrix 486DLC chip) without any FPU. Less than a frame per second, but it doesn't seem to require an FPU.

That being said, I just installed a FasMath FPU at 40MHz and it produced a far higher framerate, although still single digit. I tried lowering the screensize and level of detail while without an FPU and it didn't really seem to help any, whereas with the FPU installed, the framerate reached what I believe was double digit numbers in some instances.

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