1. A method for implementing non-standard input/output (I/O) adapters in a standardized I/O architecture, the method comprising: receiving, at an I/O hub, a request from a requester to perform an operation on one of the I/O adapters; determining that the request is in a format other than a format supported by an I/O bus; determining that the requester requires a completion response for the request; determining whether the operation generates the completion response; based on determining that the operation generates the completion response: transforming the request into the format supported by the I/O bus; transmitting the request to the I/O adapter; receiving the completion response from the I/O adapter, the completion response comprising an indicator that the request has been completed, the completion response in the format supported by the I/O bus; and transmitting the completion response to the requester; and based on determining that the operation does not generate the completion response: generating a new request, the new request in a format supported by an I/O bus; transforming the header of the new request to include the address of the I/O adapter; and sending the new request to the host system via the I/O bus, wherein the completion response is in a format not supported by the I/O bus and the new request is in a format not supported by the I/O adapter and a requester, the requester initiating the request.