B.1.7 ram segment relocation – Jameco Electronics Rabbit 3000 User Manual
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User’s Manual
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B.1.7 RAM Segment Relocation
Normally when instruction/data separation is enabled, instructions are stored in flash
memory and data are stored in RAM memory. This can present a problem for the Interrupt
Service Routine area, which often requires run-time modification. The RAM Segment
Register (RAMSR) allows a 1, 2, or 4 KB segment of the logical memory space to be
mapped as data would be mapped, even for program execution.
Table B-15. RAM Segment Register
RAM Segment Register (RAMSR) (Address = 0x0448)
Bit(s)
Value
Description
7:2
Compare value for RAM segment limit checking.
1:0
00
Disable RAM segment limit checking.
01
Select data-type MMU translation if PC[15:10] is equal to RAMSR[7:2].
10
Select data-type MMU translation if PC[15:11] is equal to RAMSR[7:3].
11
Select data-type MMU translation if PC[15:12] is equal to RAMSR[7:4].