The PCI standard requires devices to be operational even with a bus clock of zero Hz. In other words, compliant PCI cards and modules must be able to be operated statically. Hence an Atmel AVR microcontroller should be sufficient to execute PCI bus cycles step by step. Speed will be low. Nevertheless, it should be enough for relay cards and the like...
A PCI host based on the PCI/104 form factor:
The PCI slot platform allows for inserting up to three 32-bit / 5 V PCI cards:
Bring-up of the PCI project:
A relay card is used as an experimental target:
Unpopulated bus slots make good probing points...