Author: James T. Walker
Date: 09:33:03 03/14/02
Go up one level in this thread
On March 14, 2002 at 11:06:59, Alessandro Damiani wrote: >On March 14, 2002 at 07:34:59, James T. Walker wrote: > >>On March 14, 2002 at 05:56:02, Alessandro Damiani wrote: >> >>>On March 13, 2002 at 22:49:35, Robert Hyatt wrote: >>> >>>>On March 13, 2002 at 21:50:56, James T. Walker wrote: >>>> >>>>>On March 13, 2002 at 14:12:29, Robert Hyatt wrote: >>>>> >>>>>>On March 13, 2002 at 00:29:21, martin fierz wrote: >>>>>> >>>>>>>aloha! >>>>>>> >>>>>>>here's something i found on a german computer magazine website: >>>>>>>(http://www.heise.de/ct/english/02/05/182/) >>>>>>> >>>>>>> >>>>>>>"Under Windows we made use of Visual Studio 6 (with Service Pack 5), with which >>>>>>>in all probability most Windows applications have been created. The SPEC results >>>>>>>obtained with the new compilers such as the current GCC 3.0 or Intel's in-house >>>>>>>compiler are better by between ten and more than twenty percent. >>>>>>>[snip] >>>>>>>With a SPECint_base value of 306 Apple's 1 GHz machine under Mac OS X ran almost >>>>>>>head to head with the equally clocked Pentium III, combined with Linux and GCC, >>>>>>>with a SPECint_base value of 309. Under Windows, the bad quality of Microsoft's >>>>>>>run-of-the-mill compiler, which pushed the system down to a SPECint_base value >>>>>>>of 236, below the 242 value of the PowerMac running at a clock cycle of 800 MHz, >>>>>>>came back to haunt the Intel processor." >>>>>>> >>>>>>>and then there is the link http://www.heise.de/ct/english/02/05/182/qpic01.jpg >>>>>>>which shows the specint crafty result which is a whopping 444 for GCC and >>>>>>>only 293 for MSVC. >>>>>>> >>>>>>>is this really possible?? i remember i once tried GCC for my checkers program, >>>>>>>and of course it's long ago, but it was clearly worse than MSVC at the time. i >>>>>>>just can't remember anybody posting anything like this here, GCC being 50% >>>>>>>faster than MSVC... but usually, this magazine is good... >>>>>>> >>>>>>>cheers >>>>>>> martin >>>>>>> >>>>>>>PS: just another question: is linux 32-bit or 64-bit? can i use more than 2-4GB >>>>>>>ram under linux? >>>>>> >>>>>> >>>>>>1. I've never seen GCC within 10% of the speed of MSVC. I doubt it has >>>>>>suddenly happened. >>>>>> >>>>>>2. Linux is _both_. On intel (non-IA64 machines) it is a 32 bit operating >>>>>>system. On 64 bit processors like that Alpha or IA64 it is a 64 bit operating >>>>>>system. The RAM limit is not an OS issue, it is an architectural issue. Except >>>>>>for a bizarre hack Intel added a couple of years back, the 32 bit machines are >>>>>>limited to 4 gigs (2^32). With a kludge they added, this goes to 32 gigs I >>>>>>believe, but only for (at the time) the Xeons... >>>>> >>>>>Hello Bob, >>>>>Can you confirm that the P3/P4 and AMD Athlons have only 32 address lines? My >>>>>understanding of microprocessors is that the memory limit is due to the number >>>>>of address lines and not the number of data bit lines. Meaning that a 32 bit >>>>>processor can pass 32 bits in parallel but the amount of memory that it can >>>>>address is 2^X where "X" is dependent on the number of address lines the cpu >>>>>has. I remember the Motorola 68000 had something like 21/23 address lines even >>>>>though it was a 16 bit processor(Don't tie me to that exactly). I have tried to >>>>>look up the Pentium and have been unable to get a pin-out of it. >>>>>Jim >>>> >>>>I'm not sure either. I only know that the xeons have 4 extra bits that are >>>>usable, although it might be that _all_ the processors have 36 bits but they >>>>don't function on anything but xeons... no idea... I'll try to find out... >>> >>>The 68000 was 32bit (defending it :). And yes, the address space was not 2^32, >>>as Jim wrote. IIRC something like 2^24? But I never met the limit at that >>>time... >>> >>>Alessandro >> >>I believe the 68000 was a 16 bit processor (externally) but handled 32 bits >>internally. This made it a kind of bastard processor since it had a 16 bit data >>bus but operated on 32 bit words inside. The 68020 was a real 32 bit processor >>(in/out). I studied/worked with cpu's many years ago and I rember that the data >>bus being either 16 bits or 32 bits did not determine the amount of memory it >>could address. That is dependent on the number of address lines it had which >>could be any number the designers decided were required. And of course in the >>binary system the amount of memory it could address was 2^X with "X" being the >>number of address lines available. >>Jim > >You are right, but if you say "it was a 16bit processor" that means to me you >also mean internally, which is - as you say now - not true. I looked at it from >a programmers point of view. And then I had the internal 32bit to work with. >Yes, the data bus was 16bit. I did not say something against not being 32bit >externally. I thought my text was not misleading...still thinking it. But don't >worry, Jim, it was not an affront, just a detail. > >Alessandro Hello Alessandro, I did not take it as an affront. I was just trying to jog my memory as I was writing my post. Bob mentioned this before about the 4 Gig limit and I tried to find a "pin-out" of the pentium processors but could not. If the limit is truely 4 Gig then it must also have 32 address lines. It is also possible to double this with a trick of using another logic circuit to give an additional "1" or "0". This would allow you to select another 4 Gig block so that in the "0" state you can use "4Gig block A" and with the "1" state you can use "4Gig block B". It's better if the designers make another address line if more memory is needed. I have been away from electronics for quite a while and in that business a few years behind puts you in the stone age. Jim
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