Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!vsi1!wyse!mips!mash From: mash@mips.COM (John Mashey) Newsgroups: comp.arch Subject: Re: looking for >32-bit address space Message-ID: <16544@winchester.mips.COM> Date: 4 Apr 89 04:24:22 GMT References: <1032@myrias.UUCP> <3830004@hpcuhb.HP.COM> Reply-To: mash@mips.COM (John Mashey) Organization: MIPS Computer Systems, Sunnyvale, CA Lines: 34 In article <3830004@hpcuhb.HP.COM> gupta@hpcuhb.HP.COM (Mayank Gupta) writes: > >>Are there any micros or chipsets out there that support an address space >>larger than 32 bits? The current trend in micros seems to be toward 64-bit >>data paths but only 32-bit address paths. In a large-scale parallel >>processor, this starts to feel a bit like a PDP-11. >It was gonna come around sooner or later. HP saw this coming five years ago >when we developed our HP-PA (Precision arcitecture "RISC"). This gives you: > >32 bit virtual and 32 bit physical addressing : Level 0 compliance. >48 bit virtual and 32 bit physical addressing : Level 1 compliance. >64 bit virtual and 32 bit physical addressing : Level 2 compliance. > >with a very comprehensive memory management system, including levels (> 2) of >protection. > >HP has been shipping 64 bit virtual address machines. All of the above are >32-bit integer and IEEE compliant floating point machines. 1) can you say more about what this "Level x compliance" means? (Does that mean that you can build HP PA machines with 32/32, and that's called Level 0? or does it mean something other than compliance with an HP-internal spec?) 2) I suspect that the original question was looking for machines more like some supercomputers, i.e., with 64-bit integers and addresses that are used directly as such (which I don't think HP PA does: correct me if I'm wrong, but aren't there segment registers that can be controlled by the compilers, rather than 64-bit flat addresses?) -- -john mashey DISCLAIMER: UUCP: {ames,decwrl,prls,pyramid}!mips!mash OR mash@mips.com DDD: 408-991-0253 or 408-720-1700, x253 USPS: MIPS Computer Systems, 930 E. Arques, Sunnyvale, CA 94086