Initialize all registers to 0 ( set 6 and 7 to appropriate values )
Initialize MIR/MPC to 0
Initialize main memory to 0

registers = 16 * 16bit
MIR/MPC = 32 bit each
main memory = 256 * 16bit

Loop:	1) Load instruction pointed to by MPC into MIR (MPC is in # of words)
	2) MPC += 1, put values on A and B busses
	3) ALU produces output, shifter does what it must.  (amux passes
	        correct value to A-input of ALU) if MAR is set, MAR loads value
		from the B bus
	4) if MBR is set, MBR gets loaded from the C bus.  if ENC is set,
		the appropriate register is set from the C bus.  read or write
		as neccesary. 

alu has zero and negative output flags

control word format:

amux cond alu sh mbr mar rd wr enc c b a addr

amux:	0 = A latch, 1 = MBR
cond:	0 = no jump, 1 = jump if N, 2 = jump if Z, 3 = jump
alu:	0 = A+B, 1 = A&B, 2 = A, 3 = !A
sh:	0 = no shift, 1 = shift right 1, 2 = shift left 1
addr:	absolute 8 bit value

registers: 0=pc, 1=ac, 2=sp, 3=ir, 4=tir, 5=0, 6=1, 7=-1, 8=amask,
	   9=smask, 10=a, 11=b, 12=c, 13=d, 14=e, 15=f