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From: louie@umd5.UUCP
Newsgroups: net.micro.pc
Subject: Re: 80286 microprocessor problems
Message-ID: <260@umd5.UUCP>
Date: Wed, 5-Dec-84 11:27:23 EST
Article-I.D.: umd5.260
Posted: Wed Dec  5 11:27:23 1984
Date-Received: Sat, 8-Dec-84 06:33:09 EST
References: <457@intelca.UUCP> <1838@sun.uucp>
Reply-To: louie@umd5.UUCP (Louis Mamakos)
Organization: U of Md, CSC, College Park, Md
Lines: 22
Summary: 

In article <1838@sun.uucp> gnu@sun.uucp (John Gilmore) writes:
>
>I believe the original author wanted to write programs that dealt with
>more than 64K of data.  That is, he didn't want to be protected, he
>wanted to get at his data.  Given that, the question is:  how can a
>compiler generate code to subscript a (say) 128Kbyte array, such as a
>bitmap of a 1024x1024 screen, without somehow knowing how the operating
>system is going to allocate segment descriptors?  On the 8086, it was
>easy:  You take the address you want to get to, shift it down 4 bits,
>and load that into a segment register.  Then use the low 4 bits to get
>at the element you want within that segment.

This is EASY??  With microprocessors like the 68000 and the 32000 available,
with large linear address spaces, why bother?  Will this hardware induced
software rot never end?

Louis A. Mamakos
Computer Science Center - Systems Programming
University of Maryland, College Park

Internet: louie@umd5.arpa
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