----- Original Message ----- From: David VanHorn To: Sent: Saturday, October 07, 2000 12:01 AM Subject: Re: [OT]: M$; former [PIC]: Serial Communication > > > > Since the processors of that time only supported a 1 megabyte > > memory map > >and they had to draw the RAM/ROM line somewhere, is not 640K a reasonable > >place to put it? > > Sure, but structuring the whole system around the idea that this limit > would never change was pretty silly. Actually, the 'whole system' wasn't structured that way. In fact, there were products that would extend the _contiguous_ usable memory beyond the 640K line, and 'well-behaved' programs would work just fine with it. V Communications, the maker of sourcer, created one, IIRC. The real problem that prevented programs from easily moving up to 286 protected mode was segment register arithmetic and similar things. OTOH, M$'s own 16-bit Fortran, for example, managed to be _very_ portable to 16-bit protected mode by dealing with segment arithmetic in an intelligent manner. Bob Ammerman RAm Systems (contract development of high performance, high function, low-level software) -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! use mailto:listserv@mitvma.mit.edu?body=SET%20PICList%20DIGEST