64 Bit Mac OS X...?

Convert

Convert

Tech
Hey, I need this to shut a PC User-friend up. Lol.

Basically, I showed him the Powermac and told him it was 64 bit. He said that wasn't true, the only machine with 64 bit processors was a Windows machine.

I showed him the information about it, showing that it was indeed 64 bit. SO YAY!

But, he brought up a valid point, there's no OS for 64 bit. Is there a special edition of Mac OS X for 64 bit? Or does it just work on 64 bit processors anyhow?

Thanks
 
The whole point of Apple's XTools development system, that was released with Panther (OS X 10.3), is to enable the development of applications that can run in 32 bit mode on G3s and G4s and 64 bit mode on G5s. There are already parts of Panther that are capable of doing just that. In Tiger much of the OS will be capable of either 32 bit or 64 bit operation, but very likely there will be parts of Tiger that will still be 32 bit only, simply because there is little or no benefit to be gained from using the full 64 bits.
 
Tell your Windoze using friend that Windows XP 64-bit isn't out officially for consumers to use, so his point is moot. Windows XP is still causing Athlon 64s to run in 32-bit mode, so he's in the same situation as Mac OS X users currently. Besides, you could also tell him that Linux has been supporting RISC based processors like the PowerPC and POWER processors for a while now, and that will run natively in 64 bits.
 
Convert said:
He said that wasn't true, the only machine with 64 bit processors was a Windows machine.
Click to expand...
Guess he's never heard of Sun Microsystems or the 64bit machines & OS they've been producing for years.
 
mdnky said:
Guess he's never heard of Sun Microsystems or the 64bit machines & OS they've been producing for years.
Click to expand...

Or DEC Alphas or Intel Itaniums.

64 bit OSes have existed for ages. Solaris has been 64 bit for as long as I can remember. Linux has been 64 bit since '99 as I seem to recall seeing a demo of it running on the Alpha.

One of ways people who need 64 bit OSes today is to run Linux on their Powermac. I know Linus Trovalds does it.
 
I would also question your friend's knowledge of what 64-bit actually does for a machine. If he thinks 64-bits will blow the top off the computer with speed, he's sorely mistaken.

A Google search for "32 vs 64 bit" should yield a lot of hits, most of which say 64-bit computing, for the desktop, will provide little improvement other than being able to address larger amounts of RAM and disk space.
 
However, there _is_ Windows 64bit for Itanium... But that's not just a 'PC', then. According to c|net, Windows XP x64 will debut in the first half of 2005, so Tiger and Win x64 will be out about the same time. No need to pat on anyone's shoulder, anyway...

However, applications can - as mentioned - already use the 64bit-ness of the G5 partially.
 
So anybody want to go out on a limb & guess when both Windows & OSX will be completely 64 bit for all their apps. that the" general public" will be buying.
 
The 386 was introduced in 1985. It took 10 years before Window 95 was released, a consumer OS that was 32 bits. Even then, it still depended a lot on 16 bit stuff. Only when Windows XP was released (2001) did we finally have a fully 32 bit OS for the consumers.

So 16 years from the introduction of the first 32 bit consumer processor to the introduction of the first consumer 32 bit OS. Pretty long time, no?

I guess the move to 64 bits should be faster, but then the benefits of moving to 64 bits aren't as pronounced as the move to 32 bits. Since 32 bit machines will be around for a long time, your guess is as good as mine as to when they'll finally move to 64 bits completely.
 
Well, I guess it comes down to when Apple decides they can get away with dropping support for G3 and G4 processors. Could be a long time indeed.

I mean, what CPU target is XP built for? If you had a year to spare, would it boot on a 386?
 
Well, im not sure how much the base is different, but windows server 2003 will run on a P2 400 (not screaming, but it runs). It only REQUIRES (from microsoft.com) a 133mhz cpu and 128mb ram. don't forget XP was released in 2001. That's 3 years ago. we certainly didn't have 3ghz P4s then.
 
As for when everything will shift to 64 bits, the answer is never. The simple reason is that 64 bit code runs slower because it effectively doubles the traffic over the memory bus. So if your program can fit into a 32bit world it should be compiled to be 32bit. For example on my Ultrasparc which has been 64 bit for years you can count the programs compiled to run in 64 bit address spaces on one hand.

Have fun!
 
lurk said:
The simple reason is that 64 bit code runs slower because it effectively doubles the traffic over the memory bus.
Click to expand...
Actually the memory bus is a parallel bus and when you have a 64 bit machine with 64 bit registers in the processors, and a 64 bit memory bus the bandwidth (volume of data moved in a single operation) is doubled. So an operation that on a 32 bit machine would require two RAM operations can be done in one on a 64 bit machine.

If you question this take a look at the G5 iMac. If there are two unmatched RAM modules (each module is a different size) the G5 iMac operates in 32 bit mode, but if there are two matched modules it operates in 64 bit mode. Testing has shown that a G5 iMac with matched RAM modules is significantly faster than the same machine with unmatched RAM. In other words the 64 bit operation is a lot faster.
 
perfessor101 said:
Actually the memory bus is a parallel bus and when you have a 64 bit machine with 64 bit registers in the processors, and a 64 bit memory bus the bandwidth (volume of data moved in a single operation) is doubled. So an operation that on a 32 bit machine would require two RAM operations can be done in one on a 64 bit machine.
Click to expand...

Precisely, I did not say that the 32 bit machine would be faster but that the 32 bit operations moved less data. Think about it this way if you are performing computations that will fit into 32 bits. Then every int and pointer on you 64 bit machine will have 32 bits of zeros on the top. So on one 64 bit memory load you could get two 32 bit values instead of just one 64 bit value. The fact that memory access is one of the most expensive things a processor can do avoiding copying lots of useless zeros is a good thing.

So on a per process level the processor can be put into "32 bit mode" where it automatically assumes the upper 32bits of everything is 0 and then only loads or stores the lower 32 bits of data. The only time a 64 bit pointer helps you is if you need to operate on more data than will fit into a 32 bit address space. So for the vast majority of programs like 'ls' and 'cat' that would never begin to need that much space it is better to use 32 bit pointers and pull two values at a time down that 64 bit bus rather than just one.

perfessor101 said:
If you question this take a look at the G5 iMac. If there are two unmatched RAM modules (each module is a different size) the G5 iMac operates in 32 bit mode, but if there are two matched modules it operates in 64 bit mode. Testing has shown that a G5 iMac with matched RAM modules is significantly faster than the same machine with unmatched RAM. In other words the 64 bit operation is a lot faster.
Click to expand...

This is just plain wrong. The fact that the performance is faster with matched memory rather than unmatched memory is that in the matched case the system can interleave the memory between banks and in the unmatched case it cannot. When the memory is interleaved one word comes from one bank and then the next word comes from the other. Because the memory is 32 bits wide a 64 bit read takes two accesses, if the memory can be interleaved this is done in parallel if not it is done sequentially.

The important thing is that this has absolutely nothing to do with whether the system is running 32 or 64 bit code. 32 bit code that wanted to access two consecutive words in memory would show the same speedup.

Don't worry Perfessor I wont tell the tenure committee. ;)
 
FYI: x86-64 claims to be able to run both 32 and 64 bit code natively and simultaneously but there is a caveat. Your OS has to be in 64 bit mode (the 64 bit edition) and only then will in run both 32/64 bit software in an instance. But if you run a 32-bit OS on x86-64 hardware you will not be able to run 64 bit apps.

The G5 architecture however, I'm not 100% sure how it works in terms of how and when you can intermix the 2 types of software bitness. If in fact it can run 64 bit code while still in a 32 bit OS, then they have that much more leverage over the PC couterpart.
 
You must log in or register to reply here.
Back
Top