instruction_set.txt

instructions:
number is the opcode
fields with no instruction intentionally left blank

0  mov 	R0, R1/imm8 	# R0 <-- R1/imm8
1  ldw 	R0, R1/imm8 	# R0 <-- M[R1/imm8]
2  stw 	R0, R1/imm8 	# M[R1/imm8] <-- R0
3  rdw  R0, R1/imm8 	# R0 <-- P[R1/imm8]
4  wrw  R0, R1/imm8 	# P[R1/imm8] <-- R0
5  jmp 	    R1/imm8 	# IP <-- R1/imm8
6  jnz 	R0, R1/imm8 	# if(R0 != 0) IP <-- R1/imm8
7  jz  	R0, R1/imm8 	# if(R0 == 0) IP <-- R1/imm8
8  add 	R0, R1/imm8 	# R0 <-- R0 + R1/imm8
9  sub 	R0, R1/imm8 	# R0 <-- R0 + R1/imm8
A  not 	R0, R1/imm8 	# R0 <-- ~R1/~imm8
B  and 	R0, R1/imm8  	# R0 <-- R0 & R1/imm8
C  or  	R0, R1/imm8  	# R0 <-- R0 | R1/imm8
D  xor 	R0, R1/imm8  	# R0 <-- R0 ^ R1/imm8
E  sll 	R0, R1/imm4  	# R0 <-- R0 << R1/imm4
F  slr 	R0, R1/imm4  	# R0 <-- R0 << R1/imm4

it is big endian

M[] means read from memory address
P[] means read from port number

each instrucion is 16bits
each instruction is specified in this format
	AAAABBBC XXXXXXXX

	AAAA - opcode
	BBB  - R0 id
	C    - if 1 then second operand is immiediate, otherwise its register
	X3   - R1
	X4   - imm4
	X8   - imm8

	Xn meaning last n bits of X

	if some part is unused then bits should be set to 0

8 16bits registers
	R0 GP register 0 
	R1 GP register 1 
	R2 GP register 2 
	R3 GP register 3 
	R4 GP register 4 
	R5 GP register 5 
	R6 GP register 6
	R7 GP register 7

auxilary registers
	IP instruction pointer
	controlled with jmp, jz and jnz

smallest addresable unit is 16bit word
memory layout, inclusive ranges
0x0000 - 0x0FFF # instructions
0x1000 - 0x???? # general purpose 
not decided yet