STraTOS 1997 April & May/STraTOS 1 - 1997 April & May.iso/CD01/UTILS/@FALCON/DIYDSP/DSP.ASC

Text File | 1996-02-07 | 5.9 KB | 144 lines

How to clock the Falcon DSP to 50 MHz.

This article describes how to speed up the MC56001-DSP in the Atari Falcon030,
from 32MHz to 50MHz. Thus giving it a processing-power of totally
25mips and 150mops, instead of just 16mips and 96mops,
a speed increase of 56,25%.
In my case it worked, but I don't take any responsability whatsoever.
All you do with your computer, is your problem.

Tools you'll probably need:
    A small wire-cutter, or simply your teeth!
    A sharp knife, preferably a small one.
    A low-powered soldering iron (15-16W).
    Glue.
    A multimeter.
Materials you'll need:
    Some thin solder.
    3 thin wires, like 10cm each.
    One quartz-oscillator up to 50MHz (or maybe higher?!).
    One heatsink which approximatly fit the DSP (possibly not necessary).
    One 14 pin DIL IC socket (maybe 2 sockets).
    In case, some double-sided-adhesive tape.

   WARNING !
 Because I don't know for 100% sure that the partnumbers are the same
 in all revisions of the motherboard, this list applies only to Rev. D/C !


NOW TO WORK!

Before you can do anything else, you have to remove all the casing
(surprise, surprise), and all the metal-shielding in your falcon because you
need to access underneath the motherboard! This means a lot ot work, and you
have to remember where all the screws where.
Then you must locate the DSP, DMA 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. 2x2cm) marked U38 at the side of the
squared oscillator(U37)(Even on other revisions it shouldn't be too hard
to spot them.). The DMA is marked U36. The U37, quartz-oscillator,
usually supply both the DMA and the DSP with a 32MHz clock-signal.
Therefore you cannot just take away the 32MHz quartz-oscillator and
put in a 50MHz oscillator.
It is very important that the DMA gets it's 32MHz signal,
else the computer wouldn't function properly. So, how to get pass this problem?
Well, engineers at Atari have been so kind that they've made separate soldering
points for the DMA and the DSP, but since both use the same oscillator,
there has to be a connection. And, believe me, there are!

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

Note that figure 1 is precise except that the DMA and DSP is not marked with
text, only with their U-number.

The pin-configuration in figure 2 is as follows:
1    Not Connected
4    0 Volt
7    0 Volt
8    DSP clock input
11    DMA clock input
14      +5 Volt
Fig. 2  Outline of the pin-configuration on U37

Note: The 32MHz quart-oscillator occupy pin 1, 4, 11 and pin 14 of U37!!!

Underneath the motherboard there is a connection between the two soldering-
points 'Clock DMA' (pin 11) and 'Clock DSP' (pin 8).
You have to cut this connection , but be careful as the falcon has a multilayer
PCB, and by cutting too deep, you easily can ruin the computer.
To be sure that the connection is cutted properly, you better check it with a
multimeter.
The next you should do, is solder one wire to pin 7, and one to pin 8 of U37.
The third wire, you must solder to a +5Volt source.
Just use the multimeter to find one. Put one probe at the +5Volt cable (or pin)
at the powersupply, and use the other probe to find a +5Volts source some where
around the DSP. I used one of the pins in the keyboard connector at the
motherboard, the third pin one from the front and backwards i guess it was,
but you better check before you use it.
If your falcon have a 14 pin quartz-oscillator instead of a 8 pin,
you can use the same technique for the DMA's quartz as for the DSP's new quartz.


THE OCSILLATORS

This is the pin configuration of the quartz-oscillators:
1    Not connected
                4    0 Volt
11    Clockoutput
14    +5 Volt
    Fig.3 8 pin DIL oscillator

1    Not connected
7    0 Volt
8    Clockoutput
14    +5 Volt
     Fig.4 14 pin DIL oscillator

Now you can find a place to have the new quartz-oscillator,
and cut the wires so they will all reach that place (leave some more just
in case). Solder the wire from pin 7(U37) to pin 7 on the socket,
pin 8(U37) to pin 8 on the socket, and the +5 Volt wire to pin 14 on the socket.
Then you can cut the unused legs and maybe bend the wired legs to make it lower.

 Place the 50MHz quartz-oscillator in the socket, with pin 14 on pin 14,
 pin 8 on pin 8, and so on. Isolate the whole thing with electro-tape,
 or similar, and fix it on to the motherboard with doublesided adhesive-tape.
 If you unfortunately have a standard Falcon case, you must carefully consider
 where you put the new oscillator, luckily there are numerous places.

Here's an overview over the connections to be made:
14 pin quarz-oscillator    U37
Pin 1    Not Conected
Pin 7    Pin 7 (U37) 0 Volt
Pin 8    Pin 8 (U37)- DSP clk
Pin 14    A +5 Volt source

As a good rule, you should go over it all once again and
check for any mistakes you might have done, and remove all loose bits of solder
or anything else that could short-circuit your computer!

The DSP can get very hot, so some kind of cooling might be necessary,
but this isn't always the case. I let my machine open, and tried a lot of
mpeg movies, and felt with my finger on top of the DSP.
If you can hold your finger on it without it getting to hot after several
minutes of mpeg movies, theres likely no need for cooling.
Preferably, a heatsink should be used(I'm installing one as soon as I get one).
Just put a thin layer of glue on top of the DSP, and press the heatsink on top
of it. If you can afford it, use heat-conductive glue!

Now you can put everything back together.

If nothing happens when you turn on our computer,
then you should turn it off immediately and check everythingv 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.

    Geir ▓yvind Vælidalo
    Alpinveien 2B-2
    N-8500 NARVIK
    NORWAY

    E-mail: [e-mail] -or- [e-mail]