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Date: Wed, 10 Jan 79 20:26:00 GMT
Original-Date: 10 Jan 1979 1226-PST
From: Dick Gabriel <RPG at SU-AI>
To:   bug-lis at MIT-AI

 09-Jan-79  2038	Scott Fahlman at CMU-10A (C380SF50) 	Stretching TOPS-10 MACLISP  
To:   BUG-LISP    
Date: Wed, 10 Jan 79 03:18:00 GMT
Original-Date:  9 Jan 1979 2218-EST
From: Scott Fahlman at CMU-10A (C380SF50)
Subject: Stretching TOPS-10 MACLISP
To:   bug-lisp @ mit-ai
Message-ID: <09Jan79 221816 SF50@CMU-10A>

It appears that the low segment in TOPS-10 MACLISP is limited to 128K,
even though the high seg is only 28K or so.  Is this a fundamental
limitation or is there a way to get at some of the unused space for the
low seg?  As it is, the extra space available to UCI Lisp more than
compensates for the more compact code of MACLISP (sigh!).  Even if this
can't be changed dynamically, a static change to give more to the low seg
would be helpful.
-- Scott Fahlman @ CMUA

This seems to be a problem that many people would like to solve, including
SAIL. Earlier this fall there was a scheme afoot to get HIC and BH (Brian Harvey)
together at SAIL to solve this for SAIL (and presumably for TOPS-10 as well).
This has fallen through. Since we run 2.5 million words (2500k) of memory now,
we favor a 1 segment scheme. A simple possibility is to have the hiseg located
at <top-of-memory>-<size-of-hiseg> in a faked 2 segment system. U of Illinois does
this. Demand paging systems don't mind this either. The other tactic is to
put the hiseg below the loseg. Perhaps SAIL, CMU, MIT and other interested
parties could co-operate on a solution.