> It's possible that NetBSD doesn't use DMA for you disk on the tower.
> Can you post your dmesg to see what chipset this is exactly ?

Sure.  Here are ~20 relavent lines from near the top.  (The rest can be
provided if really desired.)  Note that it claims to be using DMA.


pchb0: VIA Technologies product 0x0305 (rev. 0x02)
ppb0 at pci0 dev 1 function 0: VIA Technologies product 0x8305 (rev. 0x00)
pci1 at ppb0 bus 1
pci1: i/o space, memory space enabled
pcib0 at pci0 dev 7 function 0
pcib0: VIA Technologies VT82C686A (Apollo KX133) PCI-ISA Bridge (rev. 0x22)
pciide0 at pci0 dev 7 function 1: VIA Tech VT82C586A IDE Controller (rev. 0x10)
pciide0: bus-master DMA support present
pciide0: primary channel configured to compatibility mode
wd0 at pciide0 channel 0 drive 0: <Maxtor 52049H4>
wd0: drive supports 16-sector pio transfers, lba addressing
wd0: 19541 MB, 16383 cyl, 16 head, 63 sec, 512 bytes/sect x 40020624 sectors
wd0: 32-bit data port
wd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 5
pciide0: primary channel interrupting at irq 14
wd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 2 (using DMA data transfers)
pciide0: secondary channel configured to compatibility mode
atapibus0 at pciide0 channel 1
cd0 at atapibus0 drive 0: <ATAPI 48X CDROM, 48XCDROM Ver3.30, VER-3.3> type 5 cdrom removable



  ``I probably don't know what I'm talking about.'' --rauch@math.rice.edu