[protomyth]

I've been wondering about it since like every other programmer I hit that time when I'm really looking at programming languages and VMs (in the "what would I design" sense). Looking to Lisp Machines to see what they were about leads me to the question: would concentrating on hardware memory management / garbage collection be a starting point to answer your question?

[hga]

One indication is that Azul, after 3 generations of ccNUMA systems with zillions of custom chips and a memory infrastructure that gives each one "mediocre" access speed to all the system's memory for running Java with gonzo GC ("generic" 64 bit RISC chips with things like a custom read barrier instruction), has given up and is doing their thing on x86-64 systems with their Zing product, albeit at least initially with tricks like kernel extensions to do bulk MMU operations before a single TLB invalidation. Look up their papers on the Pauseless and C4 GCs. The former was done in time to make it into the 2nd edition of sorts of the book on GC: http://www.amazon.com/Garbage-Collection-Handbook-Management...

Or to put it another way, without exhausting my bank account I could build from parts I can purchase today on Newegg a many CPUs 3/4ths TiB DRAM Supermicro system. Supermicro has standard boards with more memory, and has a monster you can only buy complete that'll hold 4 CPU chips and up to 6 TiB DRAM on daughter boards; I think based on some Googling that has a starting price of less than $35K.

Moore's Law is our friend. But its economics is not the friend of custom CPUs in competition with commodity ones.