parallel ata with disk and DVD-RW on same cable

[William Owens]

Good Day,

I have long had problems with putting disk drives and old CD-ROM drives 
on the same parallel IDE cable and have avoided doing so with more 
current DVD-RW drives till now. Is this to be expected or must I presume 
that IDE drives and ATAPI drives just cannot coexist on the same cable?  I 
have a particular need to put both on a single cable. Do I have a chance?  

Currently I have (from 'atacontrol')
atacontrol reinit ata1
Master:  ad2 <<ST3300831A/3.03> ATA/ATAPI revision 7
Slave:  acd0 <<NEC DVD RW ND-3550A/1.07> ATA/ATAPI revision 0

Because the NEC DVD drive is capable of UDMA33 as a maximum 
I have tried a 40 pin cable to limit both devices to UDMA33.
FreeBSD 7.1 recognizes this and prints a message. The problem
exists with either 40 ping or 80 cables.

If I write to the NEC DVD from the ad2 disk, both get very slow.
Writing from other devices to the DVD also causes the DVD drive
to sometimes get very slow ( ~ 1.3 Mb/sec ). The writing is done 
with 'growisofs' and uses the atapicam kernel module which turns 
/dev/acd0 into the SCSI device /dev/cd0.

Resetting with the 'atacontrol' command brings back a more normal 
speed (4-9 Mb/sec) for a time.  

So, the question, Do I have any right to expect disk drives and 
DVD (atapi) drives on the same parallel cable to work?

Thanks for your consideration.

Will Owens