This site is no longer active and is available for archival purposes only. Registration and login is disabled.

64-bit MIPS...


64-bit MIPS...

Postby Robotbeat » Jan 28, 2001 @ 4:52pm

Okay, while I was thinking about my e-115's 64-bit MIPS processor, I came up with these questions:<br><br>1)What are the advantages to using a 64-bit processor?<br><br>2)Is it possible to write a program (without a new OS) that takes advantage of the 64-bit CPU?<br><br>3)If a new OS must be written, then how is the Linux 64-bit port going? (I heard someone mention some sort of work going on with this)<br><br>4)I think that FPU emulation would be much faster with 64-bits. Am I correct?<br><br>5)Are there any 64-bit MIPS compilers out there,  must this be done in machine language, or does the programming have nothing to do with 64-bits?<br><br><br>Please, all you experienced programmers, answer these questions. If Quake could be made to compile or somehow take advantage of the 64-bit processor, this would probably make Quake very playable on Cassiopeia devices, maybe better than Ipaq.
Die, Palm, Die. If that offended you, then get rid of your Palm OS device.
User avatar
Robotbeat
pm Member
 
Posts: 827
Joined: Jan 28, 2001 @ 4:52pm
Location: In your mind...


Re: 64-bit MIPS...

Postby Christian Amor Kvalheim » Jan 28, 2001 @ 7:21pm

The MIPS core in the E105/E115 is not a 64 bit processor. Rather it is a 32 Bit processor with the ability to handle 64 bits of data in its registers. As I remeber the actual data transfer inside the chip is 32 bits wide. The only real 64 bit processors available (correct me if I'm wrong) is the 64 bit Alpha chip from DEC (Compaq). The new Intel chip (Iter..ium somthing) is also a 64 chip, but is not available on the market.<br><br>I think that the data bus on most PDAs (the bus connecting the CPU to the videomemory, etc.) are 16 bit and not 32 and driven at low frequence. The goal of a PDA design after all is strike a balance between the performance of the device and its ability to sustain operation using standard of the shelf bateries.<br><br>All this talk brings back the good old days of demo programming. Making demos to fit in 4k with as many effects as possible.. Maybe the 'scene' on the Pocket PC's will move towards that after a while. I think you can tweak quite a bit of power out of a E125 or IPAQ.<br><br>One thing you could do to make Quake run better on MIPS hardware is to develop a new MIPS compiler. The Microsoft compiler is one of the worst code generators around and does not produce optimized code.
Christian Amor Kvalheim
 


Re: 64-bit MIPS...

Postby Dan East » Jan 28, 2001 @ 9:41pm

Well, one of the misconceptions about data-width is that more is always better or faster (32 bit processors are faster than 16 bit, etc).  32 bits (IMO), is the magic number.  A 32 bit processor can handle a numerical value large enough to be useful for most real-world applications.  There are cases when binary operations (AND, OR, shifting, etc) could be performed on a 64 bit value, where with a 32 bit processor two steps would be required.  But in most cases the programmer does not need to handle numbers larger / smaller / with more precision than what can be stored in 32 bits.<br>Further, unless a specific attempt was made to optimize the code by using 64 bit values whenever posible then no improvement will probably be seen running the applicatin on a 64 bit processor.<br>Floating point emulation should be no faster on a 64 bit processor.  Again, it is all about ranges.  If the programmer is not working with values beyond what can be handled in 32 bits, then no improvement should be seen with the 64 bit processor.<br>It all comes down to this: say I can only add numbers if they are less than 10, but you can add numbers if they are less than 100.  Say you and I were in a race, and the question was, who can add the numbers 3 and 4 together faster?  My limit of 10 would have no impact, so I would not be handicapped (if we were running at the same clock speed we would tie).  However, if asked to add 25 and 30, then I would have to cleverly use several steps within my range to accomplish what you can do with one single step, thus you would win.  My point is that programmers seldom need to deal with values larger than 32 bits (which can store a signed integer between -2,147,483,648 to 2,147,483,647), so the ability of a 64 bit processor to handle the larger values in one step is not realized often.  Again, when talking about binary operations, 64 bit processors can make a difference, but binary operations are not usually performed on floating point numbers.<br><br>I agree completely with Christian about Microsoft's MIPS compiler.  I have had to try to bend over backwards to code in such a way that data is aligned on 16 bytes, otherwise the MIPS processor runs several times slower.  The compiler should handle that automatically.  That is a big advantage of the ARM processor - it is happy as long as data is even-byte aligned.<br><br>Dan East
User avatar
Dan East
Site Admin
 
Posts: 5264
Joined: Jan 25, 2001 @ 5:19pm
Location: Virginia, USA


Re: 64-bit MIPS...

Postby Robotbeat » Jan 28, 2001 @ 9:54pm

Are you sure? <br><br>I'm quite sure that it is the Pocket PC OS that is 32-bit, but the VR4121/VR4122 (or any other "VR-series" NEC cpu) is 64-bit. On the website of NEC (chip manufacturer), the chip is classified as 64-bit. I have never seen any 64-bit software for e-xxx but, I heard of someone who was going to port Linux 64-bit to e-125. <br><br>Are you positive that the chip is only 64-bit? I mean the core.<br><br>If the person who mentioned the Linux 64-bit e-125 port is reading this, could he/she please reply?<br><br>I am going out on a limb here (meaning: I haven't read technical stuff): I think that the Nintendo 64 is 64-bit! The Playstation 2 is really 128 bit, but the Dreamcast is just made with, like, 4x 32-bit thingies. <br><br>I don't want to make you mad, and I appreciate your reply!<br><br>I will also appreciate any new replies!!!
Die, Palm, Die. If that offended you, then get rid of your Palm OS device.
User avatar
Robotbeat
pm Member
 
Posts: 827
Joined: Jan 28, 2001 @ 4:52pm
Location: In your mind...


Re: 64-bit MIPS...

Postby Robotbeat » Jan 28, 2001 @ 9:58pm

Sorry, I made my last post before I saw that Dan replied! My reply is meant to be directed at Christian Amor... (It won't let me edit my post!)
Die, Palm, Die. If that offended you, then get rid of your Palm OS device.
User avatar
Robotbeat
pm Member
 
Posts: 827
Joined: Jan 28, 2001 @ 4:52pm
Location: In your mind...


Return to Pocket Quake 1 and 2


Sort


Forum Description

Discuss Pocket Quake 1 and 2 by Dan East

Moderators:

Dan East, sponge, James S

Forum permissions

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

cron