Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cwjcc!gatech!udel!mmdf
From: Chizmadia@dockmaster.arpa (David M Chizmadia)
Newsgroups: comp.os.minix
Subject: Re: PC Minix/64KB limit
Message-ID: <8920@louie.udel.EDU>
Date: 16 Feb 89 16:30:17 GMT
Sender: mmdf@udel.EDU
Lines: 56


 >  Why should he shed a tear?  Minix would be much more useful if
 >  applications could be >64k.  More usefulness means even more
 >  users!!  More users means (more money) more applications!!
 >  
 >  Actually, I think the point of Minix has changed.  It used to be
 >  a teaching OS, but it's fastly turning into a real OS (as
 >  evidenced with version 1.3 which is "self-supporting").  Any
 >  real OS on a machine needs to be able to handle the resources of
 >  the machine and I don't think 64k is even close to the resources
 >  of the PC.
 >

    Actually, as far as Andy is probably concerned, the point of
MINIX hasn't changed.  He still seems to want it to be small enough
to be understandable, so that it can be used in the classroom as an
example of how an OS manages a computer's resources.  What has
changed is the expectation of the most vocal group a contributors
to this newsgroup.  Having gotten psyched for GNU and never seen
it, they've jumped on minix as the most readily and lowest cost
realware and started trying to change it into GNU (ie. "all the
world's a VM").

     Personally, I like minix and the philosophy behind it - keep
the base system small and understandable and break the applications
into easily understandable and logically simple elements.  The only
place that I'd like Andy to reconsider the basic design of minix is
in the way it handles dynamic memory allocation - specifically, I'd
like to have the ability to dynamically request more than one
segment of memory at a time for my current process.  This would
allow large data spaces (which are perfectly reasonable for things
like editors, spreadsheets, comm programs, and databases - you
know, the stuff that makes the computer useful :-) but still force
the designer to keep the programs themselves small and to the
point.  It also keeps the compiler relatively simple since the code
generator stays the same and just the pointer size changes.  Of
course I'm biased, since most of these features are supported by
the 286 AT hardware - which is what I'd like to see MINIX run on
efficiently.

 >  I'm no engineer, but can't the PC address 1 meg?  Would it be
 >  difficult to change Minix to use this much space?  Since it
 >  isn't Messy-Dos, could it address 1 meg without those funny
 >  little LIM boards?
 >  

     Since most of the address space above 640K is preallocated to
hard- and firm-ware, yes it would be difficult to get MINIX to use
this space, however the ideas of minix, swapping, and multiple data
segments do go together well, since MINIX could just be designed to
use the LIM memory as the swap space and only swap in the current
process' data memory.

 >  Jason Coughlin

Dave Chizmadia @ DOCKMASTER.ARPA