Questions regarding IDE cable plugs, allocating primary and secondary IDE
I got 2 hard disk drives(HDD), ie:
160GB Western Digital 7200rpm 8MB Cache ATA100
- clean new disk (it is empty now)
- I am going to install Wins XP in the future
20GB Maxtor 5400rpm 2MB Cache ATA100
- old disk (some data are inside)
- the operating system is Wins 98 now
And one CD-RW:
- Ricoh CD-RW


I don't know much about computer.
Questions:
1. For the UltraDMA cable containing 3 plugs. A simple graph to show the outlook of the cable:
A+ ------------------- B+ -------- C+

Where:
+ = plug
A+,B+,C+ = plug A, B, C
--- = cable (more "-" means longer)

I would like to ask what the plug A, B, C are for?
Where should I plug?

[newly edited]
2. I wonder how to share the UltraDMA cable. I have to set primary IDE and secondary IDE. In each IDE, I have to set master and slave. Both master and slave will affect the performance mutually. How to optimize the allocation of IDE, and *why*?

In my opinion, I will set as follows:
Primary IDE
Master - 160GB
Slave - {nil}

Secondary IDE
Master - 20GB
Slave - CD-RW

Some sub-questions:
a) what's the difference in setting one as master or slave? Will the setting affect perofrmace, or anything else?
For secondary IDE, should I put master as 20GB, or the CD-RW? Which is better? and why?

3. How do I know if a cable supports UDMA 33/66/100/133?

Ultra DMA cables are 80 wire/40-pin flat ribbon cables and will feel stiffer then older 40 wire/4o-pin ATA cables. In order to take advantage of ATA66/100/133 speeds you need these to connect your drives. In a non-cable select configuration it doesn't matter which connector A,B,C you use, although most computer builders will plug A into the motherboard and B and C into the devices depending on where they may be located when mounted in the case. The Ultra DMA cables typically have A coloured blue, B coloured gray, and C coloured black. It is suggested, though I don't know if it really makes that much of a difference, that the blue connector connects to the motherboard, the gray to the slave drive and the black to the primary drive. I would put both hard drives on the primary channel and both optical drives on the secondary channel. By default your BIOS will boot from the primary master drive. But you can change the order in the BIOS.

Dear peachy,
Thanks for your answer.

I would like to know why you choose to put both HDD together, and optical drive in another IDE.

Better performance, traditionally. However, with full bus-mastering capabilities on the ATA controller it really doesn't make a difference in the benchmarks I've run.

If your using a CD-RW and a CD-ROM, and you copy cds, then you should put them on different cables.

This speeds copying up for me !