On Wednesday 26 February 2003 11:11, someone, possibly Ron Andreasen, typed:
> Primary Master - IBM 40 gb hard drive
> Primary Slave - Liteon CD-Rom
> Secondary Master - Maxtor 20 gb hard drive
> Secondary Slave - HP CD-Writer Plus 9100i

The problem here is with the UDMA (Ultra-ATA) standards. Drives that do UDMA 
above UDMA3  want to use an 80-conductor cable, as opposed to the 
40-conductor cable used by standard ATA.

Another problem is that UDMA devices (especially UDMA3+) should not be 
connected together with non-UDMA devices. While this should work according 
to the standards, many systems and driver/hardware combinations do not 
support it. According to the standards, these devices should also be 
willing to work on a 40-conductor cable, albeit at slower speeds. This is 
also not always the case. I have seen drive/controller combinations where 
systems refuse to boot if an 80-conductor cable is not used. The best way 
to solve this would be to make some changes to your configuration, here is 
a sugestion:

On an 80-conductor cable:
Pri. Master:    IBM 40GB drive, at highest UDMA mode
Pri. Slave:             Maxtor 20GB drive, at highest UDMA mode

On a 40-conductor cable:
Sec. Master:    HP CD-Writer+ 9100i, PIO4 mode
Sec. Slave:     Liteon CD-ROM, PIO4 mode

Note that while most CD-ROM/R/RW devices claim to support UDMA these days, 
very few of them actually do, and even with devices that do, PIO4 is still 
faster in the case of CD-ROMs, because of the way they work.

The problem that this set-up creates is that your drives are all still 
sharing cables. While there is nothing wrong with this, it will degrade 
performance, as IDE busses do not interleave. For a better solution, I 
would sugest you add a second ATA controller to your system

I have a controller based on the CMD649 chipset. Past CMD chipsets are 
famous for giving all sorts of trouble, but this one seems to behave, 
albeit that I need to disable write caching. The CMD649 comes on extremely 
cheap controllers, most in the sub $25 catagory, but they work just fine 
for what is needed.

If you can get your hands on such a controller, you should use a set-up like 

Motherboard ATA controller:
Pri. Master:    Liteon CD-ROM           (PIO4, 40-c cable)
Sec. Master:    HP CD-Writer+ 9100i     (PIO4, 40-c cable)

Here we make the HP secondary, because most boards will want to boot from 
the first CD-ROM, and you should be saving the writer for writing. The same 
could apply for my example earlier.


Offboard ATA controller:
Pri. Master:    IBM 40GB                (highest UDMA, 80-c cable)
Sec. Master:    Maxtor 40GB             (highest UDMA, 80-c cable)

Note that your BIOS will not directly list these drives as bootable. The 
offboard ATA controller will have its own BIOS. To get your motherboard 
BIOS to hand booting over, set it to boot from "SCSI Boot Device" or 
"SCSI". The ATA controller will then grab controle and do the boot.

You can also invert the order of devices, and have the CD-ROMs on the 
offboard controller, but because it is newer, the offboard will most likely 
support higher UDMA speeds than the onboard one, and only the onboard 
controller will be able to perform a CD-ROM boot.


Willie Viljoen
Freelance IT Consultant

214 Paul Kruger Avenue, Universitas
South Africa

+27 51 522 15 60
+27 51 522 44 36 (after hours)
+27 82 404 03 27 (mobile)


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