iAPX 432 Interface Processor Architecture Reference Manual
The IP's function set permits the I/O controller to: o alter windows;
oexchange messages with GOP processes via the standard 432 interprocess communication facility;
o manitulate objects.
These functions may be viewed as extensions to the Attached Processor's instruction set, which permit the I/O controller to operate in the 432 system.
The combination of the IP' s function set and windows, the AP' s instruction set, am possibly additional facilities provided by a Peripheral Subsystem operating system, permits great flexibility in designing I/O models. By using the more sophisticated IP functions, powerful I/O controllers can be built which are capable of relieving the 432 system of much I/O-related processing. On the other hand, by utilizing only a subset of the available IP functions, relatively simple I/O controllers can also be constructed.
1-4 •. I/O IDDEL Sur-MARY
DATA E'I1mSUMMARY
Figure 1-6 summarizes the relationship of the hardware and software components that cooperate to I1'Ove data between an I/O device and 432 system menory. Notice how the Peripheral Subsystem interface not only bridges the 432 system/peripheral Subsystem boundary, rut also can "hide" the characteristics of the one from the other. As far as a device task is concerned, its job is to I1'Ove data between memory and an I/O device; it may be completely unaware that it is connected to a 432 system. This means that existing device tasks may be utilized in a 432 system with little or no m:Xiification, and that progranmers working on device tasks need not be trained in the operation of the 432. Similarly, a GOP process which needs an I/O service need have no knowledge of the details and characteristics of the target I/O device. As far as it is concerned, it "performs" I/O in the same way it communicates with a co-operating process; by sending and receiving messages via the standard 432 interprocess communication facility.
