Thank you David.  I remember the 286 and 386 machines and Windows 3.1  My how far we have come!!!

Between all of you I think I have the information I need.  Bottom line, I will have to find other programs but it looks like my printers will be okay.  

tannis z TN

--- On Thu, 10/29/09, David Gillett <[log in to unmask]> wrote:

> From: David Gillett <[log in to unmask]>
> Subject: Re: [PCBUILD] Dell Studio 17
> To: [log in to unmask]
> Date: Thursday, October 29, 2009, 6:27 PM
> On 26 Oct 2009 at 19:37, Dean Kukral
> wrote:
> 
> > There is a little confusion here that I think that I
> can clear up.  A
> > 64 bit system - "a 64 bit architecture" - refers to
> the word length
> > internal to the cpu.  It generally represents the
> number of memory
> > locations that can be addressed in one word, two to
> the sixty-fourth
> > power.  I believe that all home computer cpu's
> have had a  64 bit
> > architecture for a good number of  years.
> 
>   There are actually THREE numbers of interest here:
> 
> 1.  The size of integer data registers in the
> CPU.  When people 
> talk about a given CPU as being "X bit", this is almost
> always 
> the number they are actually referring to.  This is
> still 32 
> bits for most Intel and compatible processors unless they
> are 
> designated "64 bit" which, although becoming more and more
> 
> common, is still a minority.
> 
> 2.  The size of address registers in the CPU. 
> This used to 
> commonly exceed the size of the integer data
> registers:  most 8-
> bit CPUs used 16-bit addresses and the 16-bit PC CPUs (8086
> 
> through 80286) used 24-bit addresses.  32-bit data
> registers 
> with 32-bit addressing has kind of been a sweet spot for
> almost 
> 20 years.
> 
> 3.  The width of the physical memory address bus
> (collection of 
> pins) on the CPU, which is almost never wider than the
> address 
> register size.  This determines the actual maximum
> addressable 
> physical memory.  For instance, the 80386 SX and DX
> processors 
> both used 32-bit address registers, but the SX had only 24
> 
> physical address pins, limiting it to 16MB of physical RAM
> (but 
> making it easy to adapt tp motherboard designs intended for
> 
> 80286 CPUs...).
> 
>   Windows 3.x was a 16-bit OS.  Most of the
> machines that ever 
> ran it had 32-bit CPUs (80386 or better), and a popular 
> optimization trick was to use the 32-bit data registers
> (which 
> required at least an 80386) for arithmetic while sticking
> with 
> the 24-bit address architecture from the 80286.  The
> Pentium Pro 
> CPU had an optimized 32-bit core, but it's 16-bit subsystem
> 
> lacked performance and so it did poorly with Windows
> customers.  
> Intel corrected that in the Pentium II, and Microsoft
> finally 
> released Windows 95 and NT 4,
>   Now we have CPUs available which provide 64-bit data
> and 
> address registers, and since XP Microsoft has been shipping
> OS 
> versions which support and take advantage of those.  A
> 64-bit OS 
> version won't run on a CPU that isn't also 64-bit.  A
> 64-bit OS 
> knows how to manage RAM that could have physical addresses
> 
> bigger than 32 bits, so is a prerequisite for systems using
> more 
> than 4GB of total address space.  (But the only 64-bit
> CPU I 
> currently own is on a motherboard that is limited to 2GB of
> RAM, 
> so CPU and OS support while required is not sufficient.)
> 
>   Windows 95 was able to support 16-bit applications
> by running 
> them in one or more virtual 16-bit environments, and the
> 64-bit 
> versions of Windows are able to do similar (better,
> actually) 
> for 32-bit applications which are still the vast
> majority.  That 
> trick doesn't really work for the OS itself, though, or for
> 
> drivers which need to act as OS components.  If you
> are buying 
> or building a new system out of pretty standard components,
> that 
> shouldn't be an issue, but if you need to support some
> oddball 
> or legacy peripherals, lack of 64-bit driver support may
> rule 
> out a 64-bit OS version.  But you may still find the
> price/speed 
> of a 64-bit CPU and matching motherboard competitive with
> 32-bit 
> versions, and the 32-bit OS and drivers etc will work on
> them 
> just fine.
> 
> David Gillett
>  
> 
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