AT&T 3B2/300 Technical Reference Manual page 358

- - - - - - - - - - - - - - - - - - - - - - - - - - - FUNCTIONAL DESCRIPTION
Virtual to Physical Address Translation for Paged Segments.
Figure 3-31 shows the translation
of a virtual address to a physical address for a paged segment of physical memory. The Section
Identification (SID) field is used to find the base address of the required Segment Descriptor Table
(SOT). The base address of the SOT for each section is stored in the MMU. This base address and the
Segment Select (SSL) field are combined to index a Segment Descriptor (SD) within the SOT. The SD
is used as the base address of a Page Descriptor Table (PDT). This PDT address is combined with the
Page Select (PSL) field to index a Page Descriptor (PD). The PD contains the starting address of the
paged segment that is concatenated with the Page Offset (POT) field to form the required physical
address.
FUNCTIONAL DESCRIPTION 3-105