What is this unused port for on A1200 mobo?

[AndyFC]

I saw this picture http://www.amiga.org/gallery/images/4660/1_4001.jpg

earlier and noticed the surface-mount solder pads to the right of the picture, near the kickstart sockets (labelled U8?). What was this used/intended to be used for please?

Thanks.

[Krischan76]

Co-Pro?

[Matt_H]

Would've been for an FPU.

[arnljot]

I think it´s for a FPU. Co-processor. I even once saw an e-bay a1200 which claimed to have one mounted and working. Don´t know if it was a custom job, or a variation from C or Ainc. Also, I don´t know if it was really working

[Zac67]

U0 is for the optional FPU - don't think any 1200 came with it, but can see no reason why it shouldn't work.

[gklinger]

This thread (at EAB) might be of interest to anyone wanting to know what's what on a 1200 motherboard.

[AndyFC]

Thanks for clarifying it. I imagine that it is much easier to add a co-pro to a plug-in accelerator.

As for cost, adding an FPU to an unexpanded A1200, plus the work to get it soldered on perhaps isn't worth it. I would spend a bit more and buy at least a fast-RAM expansion (if I didn't already have an A1230 Mk IV).

[A6000]

Without looking at the schematics, I would expect an FPU soldered on the motherboard to run at the same speed as the CPU, 14mhz, but an FPU mounted on an accelerator card can run at up to 50mhz with the appropriate crystal installed.

[mike-]

I was looking at this recently too, i had the a1200 open in front of me for a few days so it was inevitable, while looking inside i wanted to put a 25 or was it 30 mhz 020 and a fpu in there after a while, but it would require some hefty modification. as the cpu/fpu is 16 mhz, but it runs at 14, the only crystal in there is 28, which is also used to sync the video signal.

[rkauer]

 The original Amiga 1200 CPU is the 68EC020 running at 14MHz. No point in swap it for another 16MHz CPU (who will run in 14MHz, anyway).

[delshay]

FPU does not work,at least when i try to get it going,but i may have a faulty FPU,as it was taken from a faulty accelerator card.

14Mhz OSC signal is detected on one of the A1200 pads.

there also seems to be some signals missing ( to be comfirmed ).

[mike-]

rkauer

No not a 16 mhz on no, a 25 mhz, the one in there is 16.  =)

Looking at the schematics now, breaking the pin 5 connection and put a faster crystal in there might work.  

[delshay]

rkauer wrote:
 The original Amiga 1200 CPU is the 68EC020 running at 14MHz. No point in swap it for another 16MHz CPU (who will run in 14MHz, anyway).

there are 25Mhz 68EC020

[mike-]

Looks like commodore had plans to slap a 030 in there too. i saw something that looked like jumper configurations on one page there, "System configuration bits" and the 1 1 config would allow a 030>14mhz