Much16 - Simple 16-bit CPU.
==============================
An "word" is 8 bits.
Address is 16 bits, and data bus is 8 bits.
And all numbers are big-endian.

Registers
============
All registers are 16 bits.

Name   | Description
-------+------------
R0     | Generic
R1     | Generic
R2     | Generic
R3     | Generic
R4     | Generic
SP(R5) | Stack pointer
PC(R6) | Program counter

Op
=====
Should be:

Name     | Size (bits)
---------+------------
Mnemonic | 8
Mode0    | 8
Mode1    | 8

Mode1 must not be put if the op takes only 1 argument.
Mode0/Mode1 must not be put if the op does not take arguments.

Mode
=======
Should be:

Name            | Size (bits)
----------------+------------
Direct Number   | 1
Direct/Indirect | 1
High/Low/All    | 2
Reserved        | 1
Register index  | 3

High/Low/All selects if it should set/get the top 8 bits, bottom 8 bits, or all 16 bits.
High is 2, Low is 1, All is 3.

Mnemonics
============
Hex | Mnemonic  | Description
----+-----------+------------------------------------------
00  | NOP       | Do nothing.
01  | ASN M0,M1 | Assign M1 to M0.
02  | JMP M0    | Jump to M0.
03  | INC M0    | Increment M0.