sj2_2.asm(7): error A40: INVALID REGISTER

This error message indicates that there is an attempt to use an invalid register in line 7 of the sj2_2.asm file.

Registers are used to store data and perform operations in a computer's CPU. There are a limited number of registers available, and each has a specific purpose and size.

To fix this error, you should check the register used in line 7 and ensure that it is a valid register.