Jameco Electronics Rabbit 3000 - Manual (Page 293)

284 Rabbit 3000 Microprocessor
B.1.5 Memory Protection
The ability to inhibit writes to physical memory was added. The sixteen 64 KB physical
memory blocks can be individually protected, and two of those blocks can additionally be
subdivided and protected at a granularity of 4 KB. When a write is attempted, a new
Priority 3 write-protection interrupt request is generated.
The write-protection can be enabled for the User mode only or for all modes (see
Appendix C for more information).
Figure B-1. Sample Memory Protection Layout
The new memory-protection registers are listed in Table B-6 through Table B-11.
Table B-6. Write Protect Control Register
Write Protect Control Register (WPCR) (Address = 0x0440)
Bit(s) Value Description
7:1 These bits are reserved and should be written with zeros.
0
0 write-protection in User mode only.
1 write-protection in System and User modes.
0x00000
0xFFFFF
0x40000
0x4FFFF
0x48000
WPHR = 0x85
WPLR = 0x6C WPSAR = 0x04
WPSAHR = 0x07
WPSALR = 0xCC