Intel iapx 432 manual

The Interface Processor windCM mechanism provides the Per ipheral Subsystem with protected access to the contents of objects located in the 432 system. There are five windows, labeled 0-4. Each

windCM can be used to access one (single segment) object. To prevent the possible manipulation of access descriptors as ordinary data and corruption of the protection mechanisms, the windCMed object must be of base type data segment. Access descr.iptors, the basis for the 432 protection system, may he manipulated only by IP

operations supplied by the IP function request facil:i.ty. These operations are described in the next chapter.

All IP windows are sfmilar in that they support the transfer of ~ata across the subsystem boundary; this chapter first describes the characteristics corrmon to all windows. The first section covers the attributes that define windCMs; these are gener.ally specified when the windCM :i.s opened with the ALTER MAP AND SELECl' MTA SEG1ENT

function. The second section descrlbes the operation of a data transfer through a windCM that has been defined with a given set of attributes.

Three of the windCMs have special capabilities; these are covered after the basic properties of all windows have been descr ibed II WindCM 0 may be used to perform high speed block transfers. WindCM 1 may be opened onto the processor-memory interconnect address space and thus provide access to interconnect objects. Window 4-the control window--is dedicated to providing the data path for the Interface Processor function facility; this is covered in chapter 4.

Throughout this chapter conditions for correct use of windCMs are described. When any of these conditions are violated, the Interface Processor detects a fault. The !pI s fault detection, reporting and handling facilities are covered in chapter 6.

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