spim simulator pcspim : error setting value at an address

Hi I am using spim simulator pcspim and I am trying to set a value at an address using the set value option under the simulator menu.

When I try to set a value which has an msb of 1 for ex. oxb1234567 the value at that address is defaulted to 7fffffff, can anyone explain the reason for this behaviour.

Any help app开发者_开发知识库reciated

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In MIPS, addresses starting with 1 (MSB = 1) indicate kernel memory space. You cannot access kernel space from user space (which has MSB = 0) without using syscalls.