Tech Talk (02/08)
64 Bit Computing--Pros and Cons
by Brian K. Lewis, Ph.D.*
Member of the Sarasota Personal Computer Users Group, Inc.
In July 2005 I wrote an article for the Monitor on
using the 64 bit version of Windows XP. My
conclusions at that time were that most users should wait the arrival of
Microsoft’s next operating system before leaping into 64 bit computing. So
Vista’s 64 bit version (Vista x64) has now been here for about a year,
should you be considering a change from your 32 bit processor to a 64 bit
processor? I’ll lay out some of the pros and cons of this so you can make a
decision.
First, let’s consider why 64 bit processing is in the
future of computing. To do this we need to consider some very basic
information on how computers function. As most of you are well aware,
computers process information as either a 0 or a 1. Or in the really old
days of computing, these were switches that were either "on" or "off". Each
value constitutes one one binary "bit" or instruction. A central
processor with a 32 bit instruction set can process 32 bits per clock cycle.
Thus if you have a CPU that runs with a 2 GHz (2 billion cycles per second)
clock cycle, it is processing 64 billion bits per cycle. That’s the theory,
in practice there are limitations which may reduce the actual processing
speed. Anyway, a 64 bit processor could handle twice the number of bits per
second as a 32 bit processor. Again, because of other limitations, the
actual processing speed advantage is less.
There is another major advantage to 64 bit computing and
that is the size of the address space or the amount of memory that can be
used. For a 32 bit processor, working memory is limited to 2 raised to the
32nd power (2^32) or 4 GB of memory. A 64 bit processor can address 16
Exabytes of Ram. That's, 2 to the 64th power (2^64) or 16 Million
Gigabytes! At the present there are no machines that support this much
RAM. For one thing the cost of that much memory would be excessive. So
manufacturers are generally limiting motherboards and chipsets to 128 GB of
RAM or less as Vista x64 can only address up to 128 GB of RAM. The maximum
RAM is usually greater than the 4 GB limitation of the motherboards designed
for 32 bit processors.
So the question becomes, why do computers need any amount
of memory even close to any of these figures? The answer relates to how
people use their computers. A lot of users, and I’m one of them, open more
than one application at a time. This can have a definite effect on the speed
of operation of the computer. When you open an application in either Windows
XP or Vista, the operating system sets aside a 4 GB memory space for the
application, drivers and other required information. So each application
that is open has its own 4 GB memory space. It is a rare personal computer
that has 4GB or more of RAM. In fact, Windows XP can not address more that 4
GB of RAM and it uses almost one GB for its own components. So how is this
handled?
The solution to the requirement for very large RAM space
for each application is called "Virtual Memory". The computer stores much of
the required information for an application on the hard drive. It then moves
data back and forth between RAM and the hard drive as it is needed. A paging
table is used to track the locations of data on the hard drive and in RAM.
So, even when you open only a single application, a large part of it will be
stored on the hard drive or in "virtual memory". When information on the
hard drive is needed, the paging table remaps it to RAM memory and also
moves data from memory to the hard drive. Because read/write access to the
hard drive is much slower than read/write access to RAM, the overall
processing time is much slower. If you are simply doing word processing or
writing e-mail, then the speed difference is not really noticeable. If you
were doing calculations using a large spreadsheet while setting up a Power
Point presentation with complex graphics, then you would probably notice a
slight slow down in the overall operation of your system.
So the primary advantage of 64 bit computing is the
tremendous increase in address space. This advantage is also present when
running 32 bit software on a true 64 bit machine. Running 32 bit software on
Vista x64 is referred to as running on the Windows on Windows64 or WoW64. By
utilizing the added address space of x64, the time required for loading,
unloading and switching processes can be greatly reduced or eliminated. This
can also eliminate the frequent hard drive cycling that is referred to as
"thrashing", which can occur in a 32 bit system.
If you decide to move to a 64 bit system, just be sure to
add plenty of RAM. Certainly you should have a minimum of 8 GB. The
motherboard should also have a system bus designed to work with a 64 bit
processor. Otherwise the bus can become a major bottleneck. In fact, you
really should not try to upgrade a 32 bit machine by installing Vista x64.
To really be successful, you should buy a machine which is designed from the
ground up to run Vista x64. Also, the upgrade version of Vista x64 will only
upgrade the 64 bit version of Windows XP.
That brings us to the "cons" about Vista x64 and 64 bit
computing in general. 64 bit processors have been available for four or five
years for desktop computers. However, when we relate this to machines with
Windows operating systems, the big problem is slowness of the adoption of 64
bit hardware and software by manufacturers. One example is the lack of
device drivers for peripheral hardware. So just what do you need drivers
for? The one that affects most people is the printer driver. Operating
systems don’t always include a printer driver because of the great variety
of makes and models. Although I know that many HP printer drivers are
delivered along with the 32 bit Windows OS. However, this is not true for
the 64 bit version. If a 64 bit driver is available for your printer you may
have to download and install it yourself.
With Windows Vista, you not only must have a 64 bit
driver, it must be a "signed" driver or Vista will reject it. A signed
driver contains a digital signature or a certificate in the program code
which meets Microsoft’s requirements and is from a company that has a
license (Publishers Identity Certificate) from Microsoft. You may have
already encountered an "unsigned driver" message when you tried to install
software or drivers. In Windows XP and 32 bit Vista you were able to
continue the installation in spite of the lack of the signed driver. In
Vista x64 this is not possible. Vista will discontinue the installation
after advising you of the lack of the signed certificate. This procedure was
implemented to try to stop "rootkit" malware from installing itself in the
heart of the operating system – the kernel. Rootkits are able to hide within
the computer by altering register keys and processes. By blocking the
installation of unsigned device drivers Microsoft is hoping to reduce the
rootkit problem.
A driver is also needed for your graphics cards. Both ATI
and NVidia released 64 bit drivers for their newest cards in December, 2007.
There is considerable doubt that they will produce 64 bit drivers for any of
their older cards. Another reason why you have to consider new hardware when
you are thinking of transitioning to a 64 bit OS. Other hardware that needs
64 bit drivers include scanners, sound cards, modems, serial ATA (SATA) /
RAID and just about any other hardware peripheral. So you may need to update
all of your hardware in order to get 64 bit drivers. Also, since the
graphics drivers have only appeared almost a year after Vista’s debut, other
hardware manufacturers may still be working on drivers. You definitely need
to do your homework if you are considering the purchase of an x64 system.
Software is another area that is slow to take advantage
of the extra processing capacity of Vista x64. Although, as I mentioned
earlier, x64 can run 32 bit software it is done in an emulation mode. The 32
bit application can not take advantage of the wider data path that is
available in x64. Although there is some advantage due to the added memory
in an x64 machine, the software is not using the hardware to full advantage.
Just as happened when computers shifted from 16 bit processors to 32 bit
processors, there was considerable delay before manufacturers moved solidly
into the 32 bit realm.
So what applications are currently most likely to have 64
bit applications that can use the full capacity of x64?
-
Applications for creating digital content in
computer-aided design and digital video editing.
-
Applications that require mathematical precision and
floating-point performance.
-
Applications that involve large, high-performance
databases.
-
Vision acquisition and analysis applications with
large amounts of data moving directly into memory at rapid rates.
I suspect it will still be several years before 64 bit
computing will be the mainstream for personal computers. So, unless your
requirements are similar to the above list, I would suggest you stick with
32 bit systems for a while longer.
*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 2008. This article is from the
February 2008 issue of the
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