How to Read Characters in MIPS

The MIPS assembly language is a low-level programming language for processor development. Assembly is fast because it requires no compilation and works with a processor's native instruction set. However, programming in assembly requires knowledge of how to construct simple system calls that higher-level languages abstract from the programmer, such as input. For example, getting character input from the user requires loading values into appropriate registers and then manually forcing a system call from the computer.

Things You'll Need

• MIPS emulator
• Text editor

Instructions

1. Create the data for the program that will hold the character:

   .data:
   Character:
   .space 2
   .text

2. Load the integer "8" into the $v0 register, which the processor checks for system call values:

   .main:
   li $v0, 8

3. Load the reference for the "Character" variable into register $a0:

   la $a0, Character

4. Set the character limit to 1 in the $a1 register and then make the system call:

   li $a1, 2
   syscall

References

• Thomas Finley: MIPS Examples