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Yes — the fragment makes no assumptions about what is in temp registers after the subroutine call.

Other Registers

The registers are grouped into those used as variables and arguments in subroutines ($0, $v0-$v1, $a0-$a3, $t0-$t9, $s0-$s7), and those used for other purposes. Subroutines are discussed in a future chapter. The other uses are discussed as the topic arises.

The most fundamental part of an operating system is the kernel. The rest of the OS is mostly implemented using the functions provided by the kernel. Two registers, $k0 and $k1, are reserved for the kernel. Applications programs (and most OS subroutines) should not touch them.

SPIM does not come with an OS. But it loads a trap handler, if requested, which uses $k0 and $k1 as well as several of the temporary registers.

The registers $gp, $sp, and $fp are used as base registers to access to various parts of memory.


What does the following assembly language instruction do?

addu $t5,$zero,$t7

It the contents of register into register .