> 2 bits of tags, and they're thinking general purposes (e.g. GC) as well as security. That's big, something we haven't seen in hardware since Lisp Machines, to

> 2 bits of tags, and they're thinking general purposes (e.g. GC) as well as security. That's big, something we haven't seen in hardware since Lisp Machines, to my knowledge. The IBM AS/400 or whatever it is called this week uses tags too for security. (A bit is flipped if a pointer is written too thereby preventing changing pointers.) The PowerPC chip has optional support for tags because of this. Source: http://www.amazon.com/Inside-AS-400-Second-Edition/dp/1882419669 http://www.amazon.com/Inside-AS-400-Second-Edition/dp/188241...