A question about 32-bit apps running in 64-bit WIndows 7

[Al Dykes]

Does a 32-bit application run on a 64 bit machine use any sort of a
compatibility layer, not that this is a horrible thing.

Has anyone benchmarked the performance of a heavy application such as
32-bit Photoshop under 32-bit and 64-bit Windows?

(I dunno if there *is* a 64-bit build of Photoshop yet.)

 

[LouB]

Does a 32-bit application run on a 64 bit machine use any sort of a
compatibility layer, not that this is a horrible thing.

Has anyone benchmarked the performance of a heavy application such as
32-bit Photoshop under 32-bit and 64-bit Windows?

(I dunno if there *is* a 64-bit build of Photoshop yet.)

The main advantage of 64 bit is that it allows use of large amonts of
memory easily. So if Photoshop likes to use a loy of memory 64 bit
might help.
Try Google for more info/ideas

 

[Al Dykes]

The main advantage of 64 bit is that it allows use of large amonts of
memory easily. So if Photoshop likes to use a loy of memory 64 bit
might help.

I understand that and know that 32 bit apps are compiled into segments
and the is overhear in inter-segment calls. From what I know of
mainframe memory, the 64 bit flat memory model is a win for apps that
are compiled for it.

My question stands, is there any sore of compatibility layer between a
32 bit app and 64-bit Windows?

 

[Dave]

I understand that and know that 32 bit apps are compiled into segments
and the is overhear in inter-segment calls. From what I know of
mainframe memory, the 64 bit flat memory model is a win for apps that
are compiled for it.

My question stands, is there any sore of compatibility layer between a
32 bit app and 64-bit Windows?


--
Al Dykes
News is something someone wants to suppress, everything else is
advertising.
- Lord Northcliffe, publisher of the Daily Mail

Can't answer the question, but I ran 32 bit Photoshop in a 64 bit OS and it
seemed to run fine. Did not do any benchmarks. When I got 64 bit Photoshop
it seems to be faster when dealing with large documents so what Lou posted
would be applicable here. Again, I didn't do any benchmarks.
HTH,
Dave

 

[Jasper]

Can't answer the question, but I ran 32 bit Photoshop in a 64 bit OS and
it seemed to run fine. Did not do any benchmarks. When I got 64 bit
Photoshop it seems to be faster when dealing with large documents so what
Lou posted would be applicable here. Again, I didn't do any benchmarks.
HTH,
Dave

64 bit Windows uses WoW64 (Windoes on Windows) for running 32bit
applications. 32bit Windows uses WoW to run 16bit apps. WoW64 dropped
support 16bit so you cant run 16bit apps on 64Bit Windows.

From my own experiance 32bit apps on 64bit run as fast as on 32bit Windows.

http://en.wikipedia.org/wiki/Windows_on_Windows

 

[Dave]

64 bit Windows uses WoW64 (Windoes on Windows) for running 32bit
applications. 32bit Windows uses WoW to run 16bit apps. WoW64 dropped
support 16bit so you cant run 16bit apps on 64Bit Windows.

From my own experiance 32bit apps on 64bit run as fast as on 32bit
Windows.

http://en.wikipedia.org/wiki/Windows_on_Windows

Thanks Jasper, that would explain what (one of) the technical differences
are between 32 bit and 64 bit Windows. First intelligent answer I've seen
since that question was posted in a different thread.
Dave

 

[Char Jackson]

64 bit Windows uses WoW64 (Windoes on Windows) for running 32bit
applications. 32bit Windows uses WoW to run 16bit apps. WoW64 dropped
support 16bit so you cant run 16bit apps on 64Bit Windows.

Thanks, that's good to know. I have a 16-bit checkers game that I've
dragged along through 15 years of upgrades. I guess if/when I move to
a 64-bit platform I'll finally have to leave it behind.

 

[Tim Slattery]

Thanks, that's good to know. I have a 16-bit checkers game that I've
dragged along through 15 years of upgrades. I guess if/when I move to
a 64-bit platform I'll finally have to leave it behind.

Not necessarily. Check www.dosbox.com, a free DOS emulator. They say
it runs on 64-bit Vista, which doesn't run 16-bit programs, so I'd
guess it will run on 64-bit Win7 also.

 

[Zaphod Beeblebrox]

Not necessarily. Check www.dosbox.com, a free DOS emulator. They say
it runs on 64-bit Vista, which doesn't run 16-bit programs, so I'd
guess it will run on 64-bit Win7 also.

Also, AIUI the XP Mode add-on for Windows 7 (if your hardware supports
it) is 32-bit so you can run it that way.

It's amazing how far we've come, isn't it? We are casually discussing
how to run a 16-bit app in an emulator on a 32-bit emulator inside of
a 64-bit OS.

 

[Char Jackson]

Also, AIUI the XP Mode add-on for Windows 7 (if your hardware supports
it) is 32-bit so you can run it that way.

It's amazing how far we've come, isn't it? We are casually discussing
how to run a 16-bit app in an emulator on a 32-bit emulator inside of
a 64-bit OS.

Thanks, guys. Yes, we've come a long way indeed.

 

[Al Dykes]

64 bit Windows uses WoW64 (Windoes on Windows) for running 32bit
applications. 32bit Windows uses WoW to run 16bit apps. WoW64 dropped
support 16bit so you cant run 16bit apps on 64Bit Windows.

From my own experiance 32bit apps on 64bit run as fast as on 32bit Windows.

http://en.wikipedia.org/wiki/Windows_on_Windows

http://en.wikipedia.org/wiki/WoW64

 

[GreyCloud]

Thanks Jasper, that would explain what (one of) the technical
differences are between 32 bit and 64 bit Windows. First intelligent
answer I've seen since that question was posted in a different thread.
Dave

There is one more advantage to 64-bit that seems to have escaped many
people: any program compiled on a 64-bit Intel processor gets to have
access to the extra 8 general purpose registers. These extra registers
are faster than the cache memory on the chip and faster than having to
store temporary results from a calculation into main ram. That is of
course if the compiler compiles the app as a 64-bit app.
32-bit apps can't access the extra 8 general purpose registers, so there
is more overhead.

 

[LouB]

There is one more advantage to 64-bit that seems to have escaped many
people: any program compiled on a 64-bit Intel processor gets to have
access to the extra 8 general purpose registers. These extra registers
are faster than the cache memory on the chip and faster than having to
store temporary results from a calculation into main ram. That is of
course if the compiler compiles the app as a 64-bit app.
32-bit apps can't access the extra 8 general purpose registers, so there
is more overhead.

Thanks

 

[Dave]

There is one more advantage to 64-bit that seems to have escaped many
people: any program compiled on a 64-bit Intel processor gets to have
access to the extra 8 general purpose registers. These extra registers
are faster than the cache memory on the chip and faster than having to
store temporary results from a calculation into main ram. That is of
course if the compiler compiles the app as a 64-bit app.
32-bit apps can't access the extra 8 general purpose registers, so there
is more overhead.

Thanks, that makes it more logical to run 64 bit if you have a capable
machine.
What I was referring to was a post where the OP wanted to install 32 bit and
64 bit Windows on the same machine. My point was if you have the 64 bit OS
then you can run any 32 bit program or 64 bit program so (implied) you
really don't need the 32 bit since you have and can utilize the 64 bit.
I got called on this and was told I was wrong, replied with a request to
explain why that was so and no response.
So, it looks like the only limitation so far is the ability to run 16 bit
programs native on a 64 bit OS, but if the emulator will run the 16 bit
programs then it's probably back to 64 bit being the way to go.
Just my thoughts,
Dave

 

[Yousuf Khan]

Does a 32-bit application run on a 64 bit machine use any sort of a
compatibility layer, not that this is a horrible thing.

Has anyone benchmarked the performance of a heavy application such as
32-bit Photoshop under 32-bit and 64-bit Windows?

(I dunno if there *is* a 64-bit build of Photoshop yet.)

As others have pointed out, WoW64 is what is used to run 32-bit apps
under 64-bit Windows. However, it's not an emulation layer, it's just a
remapping layer. In computer science they call it "thunking". It takes
32-bit application calls and simply redirects them to the 64-bit API,
properly formatted and mapped to the right memory addresses. All 32-bit
system DLL's are simply just stub binaries that do this thunking,
passing it on to the appropriate 64-bit DLL's.

One thing to note is that all 32-bit apps will be mapped to their own
individual full 32-bit environment in 64-bit Windows. In a native 32-bit
Windows, each app would get only a partial section of a single 32-bit
memory map. So each app will think it is the only thing running on the
machine and have access to more memory by themselves.

So regarding whether there is a performance difference between 32-bit
apps in 64-bit Windows, it probably depends on what the 32-bit app is
limited by. If the app makes a lot of system calls, then it might be
limited by the thunking process, which I expect to add maybe less than
1% in overhead to the system calls. If the app is memory limited, then
it's going to find it's faster under 64-bit Windows.

Yousuf Khan

 

[Zootal]

Not necessarily. Check www.dosbox.com, a free DOS emulator. They say
it runs on 64-bit Vista, which doesn't run 16-bit programs, so I'd
guess it will run on 64-bit Win7 also.

Dosbox works great on 64 bit Windows 7. And for stuff that doesn't run in
Dosbox, you can use VirtualBox (http://www.virtualbox.org/). I run Win2000
in a VirtualBox VM for the few things I want that don't run in Win7 64 bit
or dosbox.

 

[GreyCloud]

Thanks, that makes it more logical to run 64 bit if you have a capable
machine.
What I was referring to was a post where the OP wanted to install 32 bit
and 64 bit Windows on the same machine. My point was if you have the 64
bit OS then you can run any 32 bit program or 64 bit program so
(implied) you really don't need the 32 bit since you have and can
utilize the 64 bit.
I got called on this and was told I was wrong, replied with a request to
explain why that was so and no response.
So, it looks like the only limitation so far is the ability to run 16
bit programs native on a 64 bit OS, but if the emulator will run the 16
bit programs then it's probably back to 64 bit being the way to go.
Just my thoughts,
Dave

I'm sure that the old 16-bit programs can be run somehow on win7.
Searching around with google usually yields pretty good results.

 

[Zootal]

Thanks, that makes it more logical to run 64 bit if you have a capable

machine.
What I was referring to was a post where the OP wanted to install 32
bit and 64 bit Windows on the same machine. My point was if you have
the 64 bit OS then you can run any 32 bit program or 64 bit program so
(implied) you really don't need the 32 bit since you have and can
utilize the 64 bit. I got called on this and was told I was wrong,
replied with a request to explain why that was so and no response.
So, it looks like the only limitation so far is the ability to run 16
bit programs native on a 64 bit OS, but if the emulator will run the
16 bit programs then it's probably back to 64 bit being the way to go.
Just my thoughts,
Dave

The other limitation is the lack of drivers for one-off and older hardware.
I have a few odds and ends laying around that I can't use with XP 64 of
Windows 7 64. I have a spare machine with XP32 for those things - video
capture devices, a few older webcams, and a couple of bluetooth dongles, to
be precise. None of them work with 64 bit XP or Win7.

 

[Dave]

The other limitation is the lack of drivers for one-off and older
hardware.
I have a few odds and ends laying around that I can't use with XP 64 of
Windows 7 64. I have a spare machine with XP32 for those things - video
capture devices, a few older webcams, and a couple of bluetooth dongles,
to
be precise. None of them work with 64 bit XP or Win7.

Don't know much about this, but OP wanted to install 32 and 64 bit on one
box. If it were possible to install 32 bit and 64 bit both on one machine
then I assume you'd be able to run older stuff by booting into 32 bit?

 

[John]

The other limitation is the lack of drivers for one-off and older hardware.
I have a few odds and ends laying around that I can't use with XP 64 of
Windows 7 64. I have a spare machine with XP32 for those things - video
capture devices, a few older webcams, and a couple of bluetooth dongles, to
be precise. None of them work with 64 bit XP or Win7.

I had assumed the same thing with a usb->rs232 connection - old device
- no w7 driver. However doing a search for RS232 - USB turned up a
vendor selling what appeared as the same device and who offered a Win7
driver. I installed that driver and things worked. It seems that
nearly everyone is offering Win7 support and since many devices, of
the same type, may well be built using the same internals it is
possible that with a little effort that most things can be made to
work with 7.

John B.