[jecel]

I think it is important to separate the several technical failures in wafer scale from the commercial one: Sinclair's Anamartic worked exactly as planned but the prices for conventional hard disks began to drop and that caused investors to pull out.

http://www.computinghistory.org.uk/det/3043/Anamartic-Wafer-...

The problem is that the real project was a massively parallel computer just like the Cerebras (scaled to 1989 technological limits) and the disk replacement was just a way to develop the needed techniques and finance further developments. If the investors had had a little more patience then computing in the 1990s might have been a bit more interesting.