Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!hplabs!hpda!hpcuhb!hp-ses!wunder
From: wunder@hp-ses.SDE.HP.COM (Walter Underwood)
Newsgroups: comp.arch
Subject: Re: looking for >32-bit address space
Message-ID: <580006@hp-ses.SDE.HP.COM>
Date: 4 Apr 89 23:59:03 GMT
References: <1032@myrias.UUCP>
Organization: HP SW Engineering Systems - Palo Alto, CA
Lines: 23


   Somebody had Motorola build a 68012 at one point, which was a 32 bit
   address bus 68010.

In the 68010, all 32 bits of address were brought out to pads on the
silicon.  The 64-pin DIP package only had room for 24 address lines.
The pin-grid package had 68 pins, but still only 24 address lines.  HP
asked Motorola to make up a few specials with four more address lines
brought out (making 28 bits of address).  Later Motorola stuck the
number 68012 on that configuration.

I'm not sure why HP asked for it, though it may have been in
conjunction with some LISP work that could use *lots* of VM.  The boot
ROM on the s200 boxes did some fancy work to distinguish between a
68010 and a 68012.

And yes, the HP Precision Architecture (called "Spectrum" in
development, not "Prism") has segmented memory with 32 bit segment
offsets and 0, 16, or 32 bits of segment number.  The HP9000/840 had
16 bit segment numbers.  I think that the current machines have 32
bits.

wunder