I'm not 100% sure on this (someone *please* correct me if I am wrong!) but I believe only one device at a time can be active on a given channel, primary or secondary. The result is that when both the hard drive and CD-ROM drive are on the same channel either the hard drive can be active, or the CD-ROM drive, but not both. Thus, it is usually better to place the CD-ROM drive on the secondary channel; they can then operate independently.
I would also be interested in any online info on this subject. Anybody find anything?
As far as my limited knowledge goes, is that PC's handle up to two IDE ports, Primary and Secondary. Each port can handle two devices, Master and Slave, such as a hard drive, cd-rom drive, zip drive, etc. as long as they are IDE. As to performance, I have seen nothing that designates a Master as faster than the Slave on either the Primary or the Secondary port. My guess is that if there is a difference in transfer rate, it would be to small to matter. I agree with Schultzz, let me know if I am wrong!
"Oh Bother," said Pooh, as Windows crashed for the umpteenth time.
as far as I am aware of the system cannot use both devices at the same time on the same channel, which is why IDE CD-R manufacturers recommend you have the reader as Pri-Slave & the CD-R as Sec-Master. The Master device on each channel takes priority over the Slave as it is the frist device the system checks when calls are made to the IDE channels.
To check this out try working on a file on a ZIP drive whilst copying a CD on the fly. The 2 cd's will run fine together ( if they are on seperate channels ) and the HDD ( runining the program that is using the ZIP file )will run the ZIP file exactly the same apart from the depletion of system resources obviously.
In response to Stevet below.
All the systems I build will boot from the cd-rom if enabled in the bios from master or slave regardless of the channel. I don't know what board you are using but this works on all the Giga-Byte range & the Asus range.
Who got game???? I know I do!!!!!!!
To give a more technical (Yet terse) explainantion as to why primary slave is quicker than secondary master...
Your IDE bus performs at 33MHz (Some new ones are at 66) and usually have a throughput of up to 60MB/sec.
If you are using your hard drive for anything, it will steal that bandwith from your CD-ROM and vise-versa. Both IDE channels will have the same processor bus, but the memory bus is seperate. It is all just a processes/second and throughput/sec issue. Kind of like how 2 100MHz Pentium machines can compute faster than 1 Dual-100MHz Pentium machine.
Has anyone heard of Bus Mastering?..Here is the deal. Long before the chipsets from Intel (82371FB, 82371SB, 82371AB, 430FX, 430HX, 430TX, 430VX,440FX, 82371FB, 82371SB, 82371AB)came out, the CDROM had to wait until all info came out from the HD in order to get access to it. But there is a controller called PCI Bus Master that allows the CDROM to be accesed at the same "time" as the HD. Want more info about it?.. here is a link. www.windrivers.com/company/intel/bmide.htm