Mac Mini and DDR Ram

papuapapua
Posted:
in Current Mac Hardware edited January 2014
Hi Everyone



As you can see I am new to AI. I did a search for this topic but it didn't return anything.

Is it true that the G4 doesn't take advantage of DDR? If so why does Apple have DDR in the Mini?

I'm sorry if I got it wrong but I did read it somewhere I'm sure.



Thanks

Guinea

Comments

  • Reply 1 of 6
    thttht Posts: 5,452member
    The G4 CPU in many of Apple's machines have 133 to 167 MHz single data rate front side buses. Their peak bandwidth is half of the bandwidth that PC2100 and PC2700 memory can deliver. Apple couldn't convince Motorola to change it, and thus the current situation.



    Apple is most likely using DDR SDRAM in all of its G4 systems because of availability and pricing issues compared to PC133 SDRAM, or nonexisting PC167 SDRAM. And there is a certain level of marketability involved too.
  • Reply 2 of 6
    papuapapua Posts: 2member
    Thank you for your reply THT.



    Does it cause much of a bottleneck in the system?



    Guinea
  • Reply 3 of 6
    wingnutwingnut Posts: 197member
    Interesting, I had no idea.



    As far as bandwidth limitations go, it doesn't seem too bad. I ripped a bunch of CDs on my mini today, and it burns a song to MP3 format very quickly (maybe 10sec/song by my estimates). Encoding is typically a high-bandwidth application, but it seemed to hold up pretty well.
  • Reply 4 of 6
    lundylundy Posts: 4,466member
    The G4 desktop towers used DDR, but only between the memory and the controller. The frontside bus itself was, as mentioned, 167 mhz - that's the design of the 60x Moto bus.



    Does anybody know if the mini uses the same controller as in prior G4s, namely one that actually does support DDR speed to the memory?
  • Reply 5 of 6
    skatmanskatman Posts: 609member
    Ideally, the controller-memory bandwidth should be greater than controller-CPU bandwidth so that the processor doesn't compete with DMA access from other periphery.



    Taking into account the pipeline length of the G4 and its width, I would venture to guess that the current FSB bandwidth is enough for the 1.5 GHz chip, but barely.
  • Reply 6 of 6
    beigeuserbeigeuser Posts: 371member
    Quote:

    Originally posted by lundy

    The G4 desktop towers used DDR, but only between the memory and the controller. The frontside bus itself was, as mentioned, 167 mhz - that's the design of the 60x Moto bus.



    Does anybody know if the mini uses the same controller as in prior G4s, namely one that actually does support DDR speed to the memory?



    That's true. The DDR bandwidth was utilized in PowerMac G4s in limited ways. But it made practically no difference in everyday use as shown at this page here:



    http://www.barefeats.com/pmddr.html



    It did make a difference in a highly unusual situation like this:



    http://www.barefeats.com/pmddr5.html





    For the mini, it seems that DDR RAM is used for cost and marketing reasons only.
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