ACA 1233n re stamped CPU ?

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bundyboy123

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Joined
Feb 23, 2015
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Australia
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Victoria
Hi,

I have purchased an ACA 1233n accelerator.
My question is, could the CPU be re stamped with a higher frequency rating.
The mask is 1F91C part number QEA0325.
The stamp is a light purple color and does not look like the original stamp.
Motorola stamp their 030 cpus in the middle of the gold cover, but this is stamped on the side of the ceramic.
I think this is a 25mhz cpu clocked and stamped at 40mhz.


IMG_2685.jpg
 
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Hi

I plan to replace the CPU with a socket and 68030 50Mhz.
There is a small oscillator on the right of the card that says 80 Mhz.
Is this halved for the 40Mhz cpu clock ?
Is it as simple as replacing it with a 100 Mhz for 50 mhz cpu clock ?
The card is no longer under warranty because I have install a socketed FPU.
I have a desoldering station with good suction so removing the soldered CPU is pretty straight forward.
 
Last edited:
bundyboy123 said:
Hi

I plan to replace the CPU with a socket and 68030 50Mhz.
There is a small oscillator on the right of the card that says 80 Mhz.
Is this halved for the 40Mhz cpu clock ?
Is it as simple as replacing it with a 100 Mhz for 50 mhz cpu clock ?
The card is no longer under warranty because I have install a socketed FPU.
I have a desoldering station with good suction so removing the soldered CPU is pretty straight forward.
Click to expand...
In theory, yes, it is as simple as replacing the CPU and oscillator as you suggest. In practice, the glue logic, RAM and even the impedance of the traces on the board may not be able to keep up.

There are many Amiga accelerators which used a flip-flop to divide the oscillator's frequency. The Mercury for A3000 used a 70MHz oscillator yet ran at 35 MHz.
 
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