Information about the Hard drive and list all PCI devices

$ hdparm /dev/hda

                  /dev/hda:
                   multcount    = 16 (on)
                   IO_support   =  0 (default 16-bit)
                   unmaskirq    =  0 (off)
                   using_dma    =  1 (on)
                   keepsettings =  0 (off)
                   readonly     =  0 (off)
                   readahead    = 256 (on)
                   geometry     = 16383/255/63, sectors = 234375000, start = 0

or for SCSI - $ hdparm -i /dev/sda

/dev/sda:

 Model=ST3802110A , FwRev=3.AAJ, SerialNo=9LR2AE39
 Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs RotSpdTol>.5% }
 RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=4
 BuffType=unknown, BuffSize=2048kB, MaxMultSect=16, MultSect=?1?
 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=156301488
 IORDY=on/off, tPIO={min:240,w/IORDY:120}, tDMA={min:120,rec:120}
 PIO modes:  pio0 pio1 pio2 pio3 pio4
 DMA modes:  mdma0 mdma1 mdma2
 UDMA modes: udma0 udma1 udma2 udma3 udma4 *udma5
 AdvancedPM=no WriteCache=enabled
 Drive conforms to: Unspecified:  ATA/ATAPI-1,2,3,4,5,6,7

 * signifies the current active mode
               
How fast is your drive? - $ hdparm -tT /dev/hda

                /dev/hda:
                Timing buffer-cache reads:   128 MB in  0.41 seconds =315.32 MB/sec
                Timing buffered disk reads:  64 MB in  1.19 seconds = 53.65 MB/sec

Need to find your device?

$ mount
or
$ cat /proc/partitions
or
$ dmesg | egrep '^(s|h)d'

                      hda: IC35L120AVV207-1, ATA DISK drive
                      hdc: Lite-On LTN486S 48x Max, ATAPI CD/DVD-ROM drive
                      hda: max request size: 1024KiB
                      hda: 234375000 sectors (120000 MB) w/7965KiB Cache, CHS=16383/255/63, UDMA(100)

If you want to turn on dma - $ hdparm -d1 /dev/hda

                   setting using_dma to 1 (on)
                   using_dma    =  1 (on)

List all PCI devices - $ lspci -v

         00:00.0 Host bridge: ATI Technologies Inc Radeon Xpress 200 Host Bridge (rev 01)
        Subsystem: Intel Corporation Device d600
        Flags: bus master, 66MHz, medium devsel, latency 64
        Memory at (64-bit, non-prefetchable)
        Kernel modules: ati-agp 

              ... lots more ...

           Note, there is also lspci -vv for even more information.