TT-FPU-Übertakten

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Warning! I won't take any responsibility for hardware damages caused by this modification.
Please apply it on your own risk and treat components carefully as they are very sensitive against electrostatic charges.
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hiya !

haven't you ever thought about speeding up your TT030? hmm, as long as you're working with FPU intense applications such as raytracers there's an easy hack to accelerate the floating-point processor. How much it can be overclocked depends on your 68882 FPU itself. my FPU clock could be raised to 60Mhz running at 32Mhz, initially. ah, yes - talking about initial speed there's a slight limitation of machines the modification can be realized with, i.e. only newer TT revisions which were rated @ 32Mhz. there's a neat way to find out if it can be performed with your computer if you don't know if it runs at 16 or 32Mhz. you'll just need to get and run a tool called "centbench" reporting your CPU and FPU speed. you can get it at centek's site -> http://www.graphity.fr/centek/english/s_centbe.htm .

ok, so what is this all about? well, it is about the fact that similar to the Falcon030, if equipped with a FPU, it'll be driven asynchronuosly which means that the CPU and FPU clocks can differ. you'll only need to find out how much your FPU endures before it begins to work faulty. i have seen that a standard 68888FN33 (PLCC) as present in newer TTs can be driven at up to 60Mhz without any problems. you can try to glue a heat sink ontop of it in order to achieve higher speeds or to get an FPU that even works at higher clockrates (FN50) if socketed, alternatively.

the new clock will be selected by an additional oscillator that must be fixed somewhere. glue it piggypack onto the 32Mhz crystal placed beneath the CPU fx. getting hold of suitable oscillators, wires plus a soldering iron and opening your TT's casing might be a recommendable idea, at that point.

i'd suggest starting with a 48Mhz crystal. it must be connected the following way:

 (viewed from the pin site)
     _______
    |.     .| +5V
    |       |
    |       |
    |       |
    |       |
GND |.     .| CLK
     -------

GND and +5V can be drawn off from one of the yellow capacitors nearby. the 2. step involves connecting the new clock signal to the FPU: locate a jumper (or a solderpad in some TTs) called "W101":

  W101
 _
|.| 16Mhz
|.| FPU CLK
|.| 32Mhz
 -

remove the jumper (or solderbridge) which is intended to select between 16Mhz and 32Mhz default clocks btw. and attach the new CLK wire to pin 2 (middle). that was all, actually. in case you'd like to test more oscillators there's a simple trick to test if your FPU still works: just run centbench, again. now, if the FPU frequency reported equals the one of the crystal everything works. otherwise it will report astronomical results like 205Mhz which are obviously wrong - this indicates that your FPU is clocked too high. time to fix the oscillator somewhere and don't forget to close the TT, again. now go and have some fun with your quick FPU ! ;)

ray//.tSCc.