PCIPeek 2.1 is a PCI diagnostic utility program that is useful for peeking and poking at your PCI device in its configuration, IO, and or memory space. The main commands are Display and Set, which are similar to DB/DW/DL/DP and SB/SW/SL from MacsBug. The difference is you need to append the space type to the end, so for example: if you want to Display a Byte from configuration space, you use DBC. The second argument in these commands B, W, L, and P are for byte (8-bits), word (16-bits), longword (32-bits), and P (default page of 128, 8-bit bytes).
When the program is launched, it displays: Enter new node name =>. The first step is to enter the PCI device's node name which can be found with Display Name Register utility, an example name may be: pci1000,3. If there are two PCI cards with the same node name, you can distinguish a device by appending its unit-address, such as: pci1000,3 7000. The unit-address is found in the reg property with Display Name Register.
Note, memory and IO space must be enabled before its data can be Set or Displayed. Check the Command register in configuration space 0x4 with the "C" command.
Command register bit 0 - I/O Access Enable. When this bit is set to one, the device responds to PCI I/O accesses.
Command register bit 1 - Memory Access Enable. When this bit is set to one, the device responds to PCI memory accesses.
To access ROM base memory, the ROM base register, configuration space 0x30, must have bit 0 set to one.