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FPU Speed

Started by 98pacecar, July 09, 2014, 10:47:58 AM

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I just got a hold of a second 68881 capable board and have 2 different models of the 68881, one 16 mhz and one 20. The crystals on both are at 16 mhz, so I assume both will run at that speed regardless of the speed the chip is capable of. But, is there any reason to keep the fast chip over the slower?


Shouldn't make any difference.

Logically, under clocked processors would be less prone to failure due to heat i guess as it's not pushed to its limit.
But it wouldn't make much difference in such case. Processors are typically sold for a value under the maximum clock speed it can reach to assure optimal working condition.

And personally, i have yet to see a dead FPU :)


Curious as to what you're even doing with an FPU.  I have one installed in my XVI because it has a socket for it built in so why not, but otherwise doesn't seem to do much.

Xak II and Crossfire EX are the only games that actually support one, and Crossfire wont even bother with it if you are running at 16mhz or faster.  I do have my SX Windows partition setup to use it, but I've not noticied any real peformance boost from it....


 Hi SuperDeadite !


They are Math drivers and are required for performing arithmetic operations within programs. They are almost essential because a lot of games require them.

FLOAT2.X is for stock X68000
FLOAT3.X is for X68000 + coprocessor
FLOAT4.X is for X68030 + coprocessor

Edit your Config.Sys so that it uses FLOAT3.X and you should see a difference. Try Prince of Persia to test it.

Keep the scene alive !
X68000 personal computer is called, "X68K" or "no good good" is called, is the PC that are loved by many people today.


I'm not doing anything big with these. The first one I got because it was cheap and I wanted to play with an expansion board. The second one is on the RAM card I'm using, so I didn't see any reason to not use it.

I've been running the float3.x as opposed to float2.x for a while now, but haven't noticed much difference. I don't think it can hurt anything, so I just leave it running.


Geographic Seal and Star Wars would benefit from hardware floating precision.


I need to try both of those and see how they run. I was really hoping that an FPU + 6mb ram would get Mahou Daisakusen running better, but it didn't seem to make that much of a difference. It may be *slightly* smoother, but still gets pretty laggy when there's a lot going on.


I have an 030 and its still a tad choppy. So the best bet would be a Red zone or an 030. still frameskips less than the FMT port.


Wow, it's choppy even on an 030? It's really too bad the ports are so lousy.