Foreword

Y-axis shows million operations per second...

This article describes how you can speed up the MC56001-DSP in the Atari Falcon to 50MHz. This gives it a processing-power of totally 25mips and 150mops. Compared to the original 16mips and 96mops it's a speed increase of 56,25%. The graph illustrates the speed of the DSP before and after this upgrade.

Disclaimer

I do not take any responsability whatsoever. If you choose to follow these instuctions, you do it at your own risk. I don't earn any money on this, and I have no intentions to do so either.
All I can say is that in my case it worked, but we don't have any guarantee that it'll work in your case...

Equipment:

• A pair of pliers
• A sharp knife or scalpel
• A soldering iron, preferably a 15W
• A multimeter.
• Some thin solder.
• A thin wire.
• One CMOS quartz-oscillator up to 50MHz (or maybe higher?!).
• One heatsink which approximatly fit the DSP (May not be necessary).

Remove casing

Before you can do anything else, you have to remove all the casing and all the metal-shielding in your Falcon. That's because you need to access the bottom of the motherboard! This means a lot of work, and you have to remember where all the screws went, but it's worth it!

Locate chips

Then you must locate the DSP and the 32MHz quartz-oscillator. They are positioned at the right side of the motherboard (Figure 1), right beneath the floppy drive.

The DSP is the small chip (approx. 1.5x1.5cm) marked U38 at the side of the squared oscillator(U37), and the DMA is the big chip marked U36.

U37, the quartz-oscillator, supply both the DMA and the DSP with a 32MHz clock-signal. Therefore you can't simply change the 32MHz clock with a 50MHz clock. It's very important that the DMA gets its 32MHz signal, otherwise the computer won't function properly.



Fig.1 Overview over DMA, quartz-oscillator and DSP.

Note as a curiosity that the DSP actually has 88 pins and not only 80 as Atari have printed on the PCB...

So, how do we get around this problem? Well, it's very simple; We have an extra set of ground and clock that we'll use for this upgrade (see figure 2).


Fig.2 U37-pinout

The DSP and the DMA clock have separate solder points which are connected by a small track on the bottom side of the motherboard.

Locate track

Ok, lets find that track... Turn the motherboard upside down (with the cartridge port to the right) and locate the pins from U37 as figure 3.


Fig.3 Underside the U37

Cut the track gently with a knife!
It's hard to cut too deep, but be careful anyway.

Now the DMA get it's 32MHz clock, and we can supply a new clock to the DSP.

Fit the clock

The best way to fit the new clock, is to simply bend pin 7 and 8 on the new quarz and piggyback it on the old one (figure 4.)

Fig. 4 Oscillators seen from left

Now take the wire and solder it to +5V on the quarz and to the + pole on the capacitor C121.

The pin configuration of the quarz-oscillator is the same as figure 2. The black dot on the quarz indicates the NC.
Now solder these two pins so that the quartz sits firmly onto the motherboard.

The End

If nothing happens when you turn on our computer, then you should turn it off immediately and check everything thoroughly again! If you get the Atari-logo but nothing else happens, it's possibly because the DSP don't get the new clock-signal.
If you can get it to work at all, you can simply remove the new quartz and solder a new wire between the two pin-holes where you cut the track.