I would recommend against learning MIX, and instead learn the successor, MMIX. MIX was designed in the 1960s, and as a result includes things that simply don't

I would recommend against learning MIX, and instead learn the successor, MMIX. MIX was designed in the 1960s, and as a result includes things that simply don't make sense today. For example, the number of bits in a byte is not specified. In fact, MIX is agnostic to whether or not it is a binary computer or a decimal computer! I believe for binary machines MIX says there are 6 bits in a byte, and for decimal machines there are two digits in a byte. Words are not uniform: a word consists of 5 "bytes" and a single bit, used to indicate the sign of the number. MIX has no stack manipulation instructions, and subroutines are implemented using self-modifying code. As in, in order to call a sub-routine you take your return instruction point and write it to a jump instruction in the sub-routine so it will jump back to where you want.