Jameco Electronics 2000 Network Card User Manual


 
User’s Manual 291
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].