Motorola MPC823e User Manual

Memory Management Unit
11-10 MPC823e REFERENCE MANUAL MOTOROLA
MEMORY MANAGEMENT
11
UNIT
V—Valid
0 = Segment is not valid.
1 = Segment is valid.
11.5.2 Level Two Descriptor
The following table describes the hardware-assisted level two descriptor format that
minimizes the software tablewalk routine.
RPN—Real Page Number
This field contains the physical address of the page mapped in by this entry.
PP1—Protection for the First 1K Subpage in a 4K Page
This field contains protection code for the first subpage in a 4K page. Depending on Bit 22
of the PP2 field, the same protection code has different protection schemes.
LEVEL TWO DESCRIPTOR FORMAT
BIT 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
FIELD RPN
RESET —
R/W R/W
ADDR SYSTEM MEMORY
BIT 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
FIELD RPN PP1 PP2 PP3 PP4 LPS SH CI V
RESET — ————————
R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W
ADDR SYSTEM MEMORY
NOTE: — = Undefined. The default values depend on the state of system memory.
4K PAGES WITH 1K RESOLUTION PROTECTION
PP1
SETTING
INSTRUCTION PAGES DATA PAGES
PRIVILEGED MODE PROBLEM MODE PRIVILEGED MODE PROBLEM MODE
00 No access No access No access No access
01 Executable No access Read/Write No access
10 Executable Executable Read/Write Read-only
11 Executable Executable Read/Write Read/Write

Motorola MPC823e Specifications

General

Brand	Motorola
Model	MPC823e
Category	Computer Hardware
Language	English