Speaking of 64bit ...

Note the address in the slide if you want to see the PDF files detailing the technical details of Intel's implementation. There is some question of exactly how much memory is addressable under what circumstances (AMD will only be addressing memory to 48bits), and hopefully these documents will clear that up.

In trying to understand exactly why Intel has done things the way they have, our research has turned up a couple interesting tidbits. The Intel validation process is a grueling one (as one could well imagine would develop after something as embarrassing as the original Pentium's FDIV error). It is possible that a lack of availability of software (specifically 64 bit drivers for 64 bit windows) is preventing Intel from properly completing its validation process and enabling the hardware. We have also heard rumors that Intel couldn't enable the 64 bit extensions in Prescott without the added connections provided by LGA775. This doesn't quite seem to fit either as Nocoma won't be launching with a new socket.

But we'll keep digging.

Final Words

Wednesday was mostly about Intel spreading the word about how things are moving forward as planned. There were customers for Itanium there (HP, IBM, and Dell) who mainly just spent time talking about how much their company liked Itanium. There was mention of continued adoption of hotspots throughout through out the country.

The bright side of yesterday was the Technology Showcase and meetings with some of the other companies that are here at IDF. We will be bringing you a fun filled wrap up with all the juicy goodness of the show floor and other meetings tomorrow (as we still have a few meetings to cover today), but expect to see an article on Pat Gelsinger's keynote later today.

Index
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  • TrogdorJW - Friday, February 20, 2004 - link

    Actually, a single-channel memory bus is 64-bits wide, and a dual-channel is 128-bits. DDR200 which is equivalent to 400 MHz transfers 3.2 GB/s of data. 3200 MBps / 400 MHz = 8 bytes, which is 64-bits.

    Technically, you could create 256-bit channels like they do on graphics cards, but with the trace lengths on motherboards, it's expensive and difficult to pull off. In fact, I remember one server motherboard manufacturer making a 128-bit SDRAM implementation of a P3 Xeon chipset. Back in those days, it was a pretty big deal, as it allowed you to use PC133 SDRAM and get the same performance as DDR266. Actually, performance was even faster as CL2 PC133 was available, whereas DDR266 was only available in CL2.5 at the time. It cost a lot, though: $450 or something just for the motherboard, although it was dual-proc.
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  • Pumpkinierre - Thursday, February 19, 2004 - link

    I was talking about the same thing on another post, trog #3, and someone else said that the pentium already had a 64bit wide data bus. So you wouldnt even have to double up. The extra memory on the address bus is going to be missing but you dont need that now. Really 64 bit is totally internal with the extra registers etc. so as you say a BIOS upgrade or rewrite should do it even on Sckt 478 mobo. Reply
  • GonzoDaGr8 - Thursday, February 19, 2004 - link

    I thought that the extra pins for A64 were for the dual-channel memory. Reply
  • XPgeek - Thursday, February 19, 2004 - link

    i was thinkig that the extra pins on the A64's were for increased power delivery... Reply
  • TrogdorJW - Thursday, February 19, 2004 - link

    Simple, Jeff: Like they did with the 386SX, which was a 32-bit processor core on a 16-bit memory bus. In that case, when you needed to access a 32-bit instruction, address, etc. you had to get it in two pieces.

    Really, though, AMD64/IA32e do not have as many 64-bit accesses as you might imagine. Instructions are still 32-bits, and most integers will be 32-bit. Pointers might be 64-bit (not positive), but since FP / MMX / SSE / SSE2 / SSE3 are all 64-bit or 128-bit, I think it would be quite simple (relatively speaking) to have a 64-bit processor run on the current motherboards. The biggest problem would be getting the motherboard BIOS to understand the New World Order, which would require a BIOS update at the very least, I think.
    Reply
  • Jeff7181 - Thursday, February 19, 2004 - link

    I'd be amazed if enabling 64-bit extensions didn't require a new socket (socket 775). If I'm not mistaken, isn't the increased pincount of socket 754 for the extra memory address bus width? And the added pincount of socket 940 due to the extra HT links? Why would it be any different for Intel? If they're using 478 pins right now, how could they increase the size of the memory bus without adding more pins? Reply
  • Pumpkinierre - Thursday, February 19, 2004 - link

    You're on the right track, happy digging! Reply

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