[earthbee]

"Some 3rd parties produced boards that could contain a Blitter chip, but I’m not aware of anyone directly adding one to the board."

My 520ST was upgraded with 2.5MB of RAM and an added blitter chip, so it did happen. I still have the computer and it was still working the last time I powered it up a few years ago.

[OnlyMortal]

A school friend of mine added an fpu.

I’d lent him a Mac Plus with a copy of Excel on it. He was using it as a reference when writing his own spreadsheet.

He’d previously written one for the Spectrum called “TasCalc” and had done some GEM programming, a product he sold as “Proshare ST”.

It downloaded stock prices from Teletext via an adapter.

Smart lad.

[lokedhs]

There was no FPU for the 68000. This was supported by the 68010, which was not present in any Atari computers. Are you sure he didn't add it for the Falcon, which did have a slot for an FPU.

[OnlyMortal]

He had a straight 512ST and added manually a FPU. He bought some board to do that.