I made some money in the 80's by drilling holes in a very specific spot on a package moulded around the chips in Philips 27 MC rigs. They were originally intended for the US market and had 40 channels, the modifications reduced that to 22 channels. But the switch still had 40 positions, which was a giveaway that this was a mod rather than a redesign. I figured out where to drill in the plastic package that was moulded around the original chip (and to what depth!), and charged 50 guilders for the mod (which took about 5 minutes with an appropriately designed jig).
Fun days, all I was after was to destroy that extra circuit so accuracy wasn't too important.
As far as the SX is concerned the wp article you linked states fairly explicitly:
"If testing showed that the central processing unit was working but the FPU was defective, the FPU's power and bus connections were destroyed with a laser and the chip was sold cheaper as an SX; if the FPU worked it was sold as a DX."
If they needed more SXs and used their laser on the die then I guess that was a pretty hard to reverse operation :)
I made some money in the 80's by drilling holes in a very specific spot on a package moulded around the chips in Philips 27 MC rigs. They were originally intended for the US market and had 40 channels, the modifications reduced that to 22 channels. But the switch still had 40 positions, which was a giveaway that this was a mod rather than a redesign. I figured out where to drill in the plastic package that was moulded around the original chip (and to what depth!), and charged 50 guilders for the mod (which took about 5 minutes with an appropriately designed jig).
Fun days, all I was after was to destroy that extra circuit so accuracy wasn't too important.
As far as the SX is concerned the wp article you linked states fairly explicitly:
"If testing showed that the central processing unit was working but the FPU was defective, the FPU's power and bus connections were destroyed with a laser and the chip was sold cheaper as an SX; if the FPU worked it was sold as a DX."
If they needed more SXs and used their laser on the die then I guess that was a pretty hard to reverse operation :)