iAPX 432 Interface Processor Architecture Reference Manual
The performance of a function may be considered fram the AP point of view as a sequence of three phases, as shown in figure
The IP executes functions serially; requesting execution of ~ second function before ~ prior function has been completed produces an undefined result. The function completion state subfield of the function state field (see appendix A) indicates the IP' s readiness
to accept a function request. A typical IP controller implementation will assign responsibility for requesting functions to a single routine (task) which will serialize the requests.
Given appropriate Peripheral Subsystem bus arbitration, function requests (which are identical to all windowed transfers) may be
issued concurrently with other window activities. For example, consider a IJ.1A controller driving a block rrode transfer through
window O. If the IJ.1A controller relinquishes the Peripheral Subsystem bus .between transfer cycles, the IP controller (running on the Attached Processor) can use the rus for a function request (or for any other purpose).
PROCESS SELECI'ICN
The IP controller must specify that a function be performed in one of the IP process environments which exist in the 432 system. To select a process, the IP controller must deposit a process selection index into a designated slot in the function request facility area of the processor data segment. Wi th this index, and the process list in the IP's processor object, a process object can be located. The IP will attempt to qualify and lock the specified process as soon as a function opcode is written.
FUNCrICN OPCODES
Each function is uniquely identified by a
