Tech Talk (09/08)
Is It Time to Switch to 64 Bit Windows?
by Brian K. Lewis, Ph.D.*
Member of the Sarasota Personal Computer Users Group, Inc.
In my February 2008 article in the Monitor
comparing 32-bit and 64-bit computing, I was still advising caution for those wishing to upgrade. Today
every new computer is capable of running a 64-bit operating system. As a
result there are many voices saying if you have the capability to run a
64-bit operating system, you should take advantage of it. Microsoft had
previously indicated that Windows 7 would be available only in a 64-bit
version. However, they now say both 32 & 64-bit versions will be sold.
There is some speculation in the computer industry that Windows 8 may
only be 64-bit. So it appears to be time to reconsider the move to a 64-bit operating system (OS). There are many advantages for 64-bit over 32-bit, but in order to better understand them, we need to take a brief
look at how these will affect your decision.
To start with we should recall a little history. In
the early days of personal computing the processors instruction sets
were designed for 8-bit "words". This was the data size that could be
used to express a single character. A bit is either a "1" or a "0".
Eight bits were then referred to as a "byte" and that was considered a
computer "word". In those days the CPUs we had were the Intel 8080, the Zilog Z80, Motorola 6800, and the MOS Tech 6502. These were all 8-bit
processors with 8-bit data paths. The Apple I/II/IIe and Commodore Pet
all used the 6502. IBM designed the first x86 CPU which was called the
8086 and it was a 16-bit processor. However, when IBM produced their
first personal computer in 1981 it used their 8088 processor which was
an 8-bit version of the 8086. The next step was to the 16-bit processor
with the 80286 processor in 1984. The software changes rapidly followed
this advance. The change to 16-bit processing allowed the central
processor and the data bus to transfer data in increasingly larger
sizes, referred to as double words. The 32-bit processor arrived in 1989
followed by the 64-bit in 2005. As this history shows, the 64-bit
computer is just one more generational step in processing power. In
addition, a computer "word" is now considered to be 16-bits, not 8-bits.
So a 64-bit processor can handle a quadruple word (4x16). Naturally, the
increase in the width of the CPU/data path does increase processing
speed.
Every time the hardware has changed, there has been a
delay while the software manufacturers play catch-up. Applications have
to be rewritten to take advantage of the hardware changes including the
new instructions in the CPU instruction set. Only then can the
application take advantage of the added processing power. Although
Windows has been available in a 64-bit form since XP was released, it
adoption has been quite slow. Many software manufacturers did not make
64-bit versions of their applications. This coupled with the limited
acceptance of Vista has markedly slowed the shift from 32-bit to 64-bit.
Another factor in this process is the development of 64-bit drivers for
peripherals such as printers, scanners, graphics cards, wireless modems,
network cards, etc. Microsoft has also indicated that Windows 7 will not
install 64-bit drivers unless the software is "Microsoft Certified".
Some manufacturers have obtained certification for some of their 64-bit
drivers. For example, my Brother multi-function machine has a certified
driver for 64-bit Windows. If you don’t have a 64-bit certified driver,
your peripheral will not work under Windows 7. Neither Vista64 nor
Win7-64 will accept 32-bit drivers. Something to check out before you
pop for a 64-bit OS. However, if you are buying an upgrade version of
Windows 7, several of them are supposed to come with both the 64-bit and
32-bit versions in the box, but not in the OEM versions. This
specifically applies to the Home Premium, Professional and Ultimate
versions (as of this writing and may be subject to change by
Microsoft.).
Another advantage of a 64-bit processor is in its
memory management. By now I would hope that everyone understands that
the 32-bit generation of computers can address a maximum of 4 gigabytes
of RAM. This is the maximum number of addresses that can be handled and
is calculated from 2^32 or two to the thirty-second power. This includes
addresses needed by the system as well as the data. A 64-bit processor
can address 2^64 addresses or roughly ten billion more than the 32-bit
processor. The catch here is that both the hardware manufacturers and
Microsoft have imposed limitations on the addressable memory. Generally,
new personal computer’s are limited to 128 GB of memory or less. Some
manufacturers configure their laptops for a maximum of 4 GB of RAM.
Windows OS software is also highly variable in its limits. Some versions
of Vista limit addressing to as little as 8 GB (Home Basic & Premium).
It is expected that these limits will be raised in Windows 7. For the
present, these levels should be more than adequate for most people. If
not keep in mind that it is the Ultimate versions of Vista and Windows 7
that have the maximum addressing ability.
The next thing to consider is the software
compatibility. Just because you have a new operating system, no one
really wants to have to upgrade all their software from 32-bit to 64-bit. For that reason both Intel CPU’s and AMD CPU’s are not true native
64-bit processors. They are, in fact, hybrids. By this I mean that they
allow 32-bit code to run in an emulation mode. Consequently, 64-bit
Windows has an emulation mode, Windows on Windows, which allows 32-bit
software to be run. WOW intercepts system calls to the operating system
made by a 32-bit application and switches the CPU to 32-bit mode. It can
switch the CPU between 32-bit and 64-bit as needed. This also allows the
64-bit AMD/Intel CPU’s to run a 32-bit OS. The only true 64-bit,
non-hybrid operating systems for PC’s are found in Intel’s Itanium
processor (IA64) and the various 64-bit versions of Linux. Systems using
these CPUs will give you all the benefits of 64-bit computing, but
require all 64-bit software. Windows WOW64 also allows for some 32-bit
software to run on the IA64 CPU by converting 32-bit calls to 64-bit.
Windows XP, Vista and Win7 contain large numbers of
dll files. These are system libraries, many of which are loaded into
memory when the computer is booted. In the 64-bit OS, these libraries
can not be used by 32-bit software so instead, there are duplicate
libraries written in 32-bit code included in Windows. Microsoft has
devised a system so that these libraries can co-exist on the hard drive
and in RAM without overwriting the files or accessing the wrong file so
that 32-bit code can be run under the 64-bit OS. Sounds good, doesn’t
it? Yes, it does work, but with some caveats. Adding an emulation layer
does slow the overall processing of software instructions. Also, there
is an increase in the amount of memory (virtual memory included) needed
for the additional 32-bit libraries that are loaded along with the
64-bit dlls at boot time.
There are other problems, but to a somewhat lesser
extent as it affects fewer software applications. Some 32-bit
applications still use 16-bit loaders. Since Windows 64 does not support
ANY 16-bit code, these applications will not run, unless
Windows can transparently substitute an installer with 32-bit code.
Hopefully, all 32-bit software will eventually have 32-bit loaders or be
replaced with 64-bit code. Additionally, some 32-bit software requires
the use of 32-bit drivers. These drivers will not run on any 64-bit
Windows platform. So until the drivers are available in a 64-bit form,
these applications can’t be used with Windows 64.
Another consideration is that any utility software
that works at the hardware level must be 64-bit. This generally includes
anti-virus software and other anti-malware products. Those few
manufacturers I have checked do have 64-bit versions of their
applications available. This includes some which provide free utility
applications. This is just one more item that should be checked before
you decide to move to a 64-bit OS.
If you decide you want to upgrade to the 64-bit
version of Windows 7 when it is available, then you have several more
things to consider. No matter which 32-bit Windows version you are
currently using, you will have to do a "clean" install of the 64-bit
version. That means backing up your data to an external medium and
formatting your hard drive or at least a part of it (one partition). You
can install Windows 7 in a new partition and dual boot with it and your
current Windows version. Or you can install the new version in the space
reclaimed from your old version. Either way you will have to reinstall
software and drivers. Then you can restore your data. Only if you
upgrade to the Windows 7 32-bit version from Vista can you do an
"in-place" upgrade. If you are still running XP you have no choice but
to do a clean install to convert to the 64-bit version. Of course, if
you buy a new computer with the 64-bit Windows 7 installed that reduces
your problem to just installing applications and data from your old
computer.
I have already pre-ordered a 64-bit version of Windows 7. So, you
see, I have answered the question I posed in the title of this article.
When it arrives, in October, I will be installing it, then testing
drivers and applications. You probably won’t see any of my experience
until the December Monitor. In the meantime, I have obtained a 64-bit
version of the Linux OS, Ubuntu. Over the next few months I will be
installing and testing it on my computer. So you will be seeing more
about 64-bit computing. I hope it will help you as the entire industry
continues to move into a fully 64-bit era. Just think, the next move, in
a few years, will probably be to 128-bit computing!
*Dr. Lewis is a former university and medical school professor of physiology. He has been working with personal computers for over thirty years, developing software and assembling systems. He can be reached at bwsail at yahoo.com.
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Copyright 2009. This article is from the
August 2009 issue of the
Sarasota PC Monitor, the official monthly publication of the Sarasota
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