difference between 16-bit & 32-bit OPERATING SYSTEMS

difference between 16-bit & 32-bit OPERATING SYSTEMS

Post by Spiros Ioann » Sun, 15 Feb 1998 04:00:00



: Hi,
:
:       I am kishor. what exactly the difference between 16-bit & 32-bit
: operating systems. because there are lot of applications that run only on
: the 32-bit operating systems. Actually these 16-bit & 32-bit matter is
: related to HARDWARE. the operating system is more or less software. So
: how much significant it is to relate this bit's matter with operating
: system.

Well, this is mainly for 80x86 cpus which work either in protected or real
mode . The difference is memory addressing (in real mode it's divided into
pages -> slower addressing) but with 8-bit/16-bit registers you can't
address a lot of memory...(leftolfs from early 80x86=> I HATE compatibility)
So, talking about msdos (LINUX is runing in protected mode) a 32bit operating
system is a 16-bit operating system, recompiled with a 32 bit compiler!
(without the "far" declarations in C e.t.c. and some other minor modifications
of course) A Lot of marketing noise about nothing...

-Spiros

 
 
 

difference between 16-bit & 32-bit OPERATING SYSTEMS

Post by Kaz Kylhe » Tue, 17 Feb 1998 04:00:00




>Hi,

>    I am kishor. what exactly the difference between 16-bit & 32-bit
>operating systems. because there are lot of applications that run only on
>the 32-bit operating systems. Actually these 16-bit & 32-bit matter is
>related to HARDWARE. the operating system is more or less software. So
>how much significant it is to relate this bit's matter with operating
>system.

Discussing 16 versus 32 bit *operating systems* these days makes sense only
when you are talking about the PC operating systems from Microsoft such as
MS-DOS; DOS is one of the last operating systems that was written
in assembly language exclusively for a single processor architecture.

UNIX has always been written in a high level language which, to some
extent, makes the specific ``bitness'' of the processor *somewhat*
irrelevant when we are discussing UNIX, at least on a broadly general level.

A good example to look at is the XINU operating system (a miniature,
experimental UNIX-like OS) which was originally implemented on an DEC LSI-11
16 bit microcomputer, but was later ported to 32 bit systems based on the 68K
and 386 family.

Quote:>    I am very greateful to you if you provide a single line of clarification.

How significant is it to relate the hardware bitness to the operating
system?

First of all, there is the issue of address space. A computer which addresses
memory wit 16 bit addresses has a very restricted address space of 64
kilowords: far too small for all but trivial applications. In the 8086
architecture, the limitation is partially overcome by the use of segments,
which allow the processor to address a megabyte in an awkward way, rather than
a flat address space. This is still very restricting. Under a 32 bit
architecture, the addressable memory is huge. Address space doesn't mean that
you have a lot of memory; it is the potential to access a lot of memory.
Virtual address translation (virtual memory) can give you the illusion that
you have a lot of space---but only if the address space is there to begin
with!

This brings us to something that as important as address space size: memory
management hardware.  The 8086 processor family, for which the MS-DOS and 16
bit Windows operating systems were exclusively written (with, admittedly, some
weak, ``ehanced'' support for the 386 in Windows 3), does not support memory
management; there is no distinction between user and supervisor processes,
there is no virtual memory, and no protection between memory regions belonging
to different tasks.  Combined with ill design and poor engineering on the part
of you-know-who, this creates an extremely unstable computing environment.

[ Note that the Macintosh systems have been ``32 bit'' for a long time,
but have always been extremely unstable due to their underutilization of the
memory management hardware! The Amiga and Atar ST operating systems
were just as bad! Bitness isn't everything. ]

It is convenient to blame the limitations and instability on ``16 bit'' and
market ``32 bit'' as the holy grail---evidence of which can be seen
in the mass advertising enjoyed by the Wintel culture.

If you really want to understand, you should delve into the study of computer
architectures; there exist some excellent introductory textbooks.

 
 
 

1. difference in operating system interface in 32 bits and 64 bits mode

Hi, The title says it all!
Does operating system interface (Services,system calls) change during the move
to 64 bits mode.
Also, what are the types that change size (I know long and void * chage, but
I think there are operating system types that also change).

Thanks for your help!!

2. Internet Provider & PPP

3. SpeedStar64 on 16-bit & 32-bit modes

4. ftp,telnet

5. I need to run 16-bit executable on 32-bit OS

6. HOW I CAN TRANSLATE THIS

7. Gcc/Assembler Dumps Core

8. How to run a 16-bit executable on a 32-bit OS?

9. Can't use 16-bit, 32-bit modes

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11. mrand48() returning 16-bit longs, instead of 32-bit

12. Calling 16-bit PM code from 32-bit PM Kernel Driver