A friend would like to know when logic vs will be shipping and how much it will be? thx weld Ray Keefe wrote: > From: "Ray Keefe" <ray@a...> > > Hi, > > maybe I should give a bit more info. > > 1. bus mastering helps because it lets the controller do more of the work > and offloads effort from the CPU so bus mastering is definitely a good thing > in general. > 2. DMA can actually harm things if the bursts are log enough because the CPU > is halted during the DMA transfer which means it cannot service IRQs nor can > it move data itself. The advantage of DMA is that, like bus mastering, a > whole bunch of stuff happens wiythout CPU overhead, state saves and restores > etc. So Small burst DMA combined with bus mastering can really improve > performance. > > The main issue I was addressing was that of moving data from one spot on a > hard to disk to another spot on the same hard disk. This is where the disks > on board cache and controller can play an important part in the equation. > The normal process is to move the data off the hard disk via the on board > cache, then move it back onto the hard disk via the on board cache. > Provided the data all fits in the cache there is no problem. Once the data > exceeds the cache size then you end up with it going externally, then back > onto the drive. This is obviously slower. Because the original destination > is in a different spot to the final destination then the heads must also > move more. > > If you have a separate hard disk, you avoid many of these problems. This is > also where bus mastering can help more. The data can be run off one hard > disk and onto another without much CPU intervention. > > This is why it is recommended that the hard disk your system runs from is > physically different to the one that the audio data is streamed from. > > Ray > > -----Original Message----- > From: owner-logic-users@m... [mailto:owner-logic-users@m...]On > Behalf Of Pipeline@c... > Sent: Wednesday, 1 September 1999 10:45 > To: logic-users@m... > Subject: 2nd hard drive > > Also Ray suggested that DMA and Bus Mastering do not come into play unless > you are transfering audio from one drive to another, so is in fact useless > for playing back audio. > > Is this correct? No, This is not correct > > I thought that bus mastering was supposed to take the load of the cpu for > basic hard disk tasks > > This is correct > > Frank W Kooistra > . > > --------------------------- ONElist Sponsor ---------------------------- > > ONElist now has T-SHIRTS! > For details and to order, go to: > <a href=" http://clickme.onelist.com/ad/tshirt1 ">Click Here</a> > > ------------------------------------------------------------------------