Persistence: a proposal
Thu, 22 May 97 23:39 PDT
>>>>> "David" == David Gadbois <email@example.com> writes:
David> [Scott, Kelly, and Patrick discuss Smalltalk 80-style
David> object tables. It is kind of weird to think that all of
David> this stuff, which still seems so cutting-edge, was
David> originally proposed 20 year ago when I was still in grade
Think of this: Xerox had in-house publishers running personal
workstations with bitmapped displays, WYSIWYG editors, laser printers,
and ethernet in 1974.
David> Will the tots of today be raving about parametric
David> polymorphism in the 2010's? I don't think so.]
Which is why a brand-new OS should be aggressively challenging the
standards of the 80's.
David> Having object-table handles does make it easier...
One thing to keep in mind is that things are never quite what they
seem. Although the "Smalltalk-80" programming model presents object
tables and Gemstone carries that idea forward conceptually, a lot of
tricks are played to make it really work.
David> It also does give up half the address space, already a
David> precious commodity on 32-bit machines.
But, like the Texas Persistent Store from U. Texas (damn, another
reference to "research"), a 64-bit address space can be swizzled into
a 32-bit system. The effective address space doesn't have to be limited
to 32-bits. Especially if the LispOS should run on Alphas, the
upcoming 64-bit Intel/HPs, the 64-bit SPARCS, etc. Then a 64-bit
address space can map into 64-bit systems and 32-bit systems
Which is another reason starting with RScheme and Texas is an idea to
consider. Although I don't know if Texas is already a 64-bit system or
simply an idea.
Another idea tossed around for 64-bit addresses is to use 64-bit IEEE
floating point as the OID format. All non-float addresses are encoded
within NaN format. Does someone have a reference to what this looks
like. I haven't found anything on the net that describes the actual
layout of the bits for NaN.
Patrick Logan mailto:firstname.lastname@example.org
Voice 503-533-3365 Fax 503-629-8556
Gemstone Systems, Inc http://www.gemstone.com