There's a socket soldered to my ST's cpu?

[Globox]

Was looking at the motherboard of one of my Atari ST's, and it seems like the previous owner did something to it.
There's a socket soldered to the CPU, but nothing is plugged in there.
Does anyone know what the purpose of this socket could have been?
Maybe debugging?

Schermafbeelding 2020-09-19 om 20.02.48.png

[czietz]

Many 3rd party extensions are connected in parallel to the CPU. Soldering a socket on top of the CPU is a common way of doing that.

For example this photo is from the Lightning ST / Storm ST / Cloudy installation guide. (http://wiki.newtosworld.de/index.php?title=Lightning_ST, http://wiki.newtosworld.de/index.php?title=Storm_ST)

[Globox]

Hmm I wonder what it was for, previous owner said it was sitting in his attic since the 90's

[czietz]

Like I said: A lot of add-ons were/are connected in that way. Vofa graphics card, maybe? PC Speed for MS-DOS compatibility, perhaps? There really were many add-ons back then.

In case you're wondering what to do with it: You can simply leave it as it is, it won't cause any issues. Or you can use it as a starting point to install your own set of add-ons.

[Globox]

Good to know, might come in handy! :D

[rubber_jonnie]

Yep, had a couple of PC emulators that fit this way.

[exxos]

Looks wonky ?

But yep, can plug in expansions that way..

[dgw]

Had to do this to install the PCspeed emulator board (and cutout top shield). Never used it much so removed it. Be interested to hear of any possible uses for piggy-backing something more useful onto it :-)

pcspeed.jpg