nut version 2.0

change from 0.1

1  have global variables
2  improve microarchitecture: no rt, use pushe (one cycle faster), no F, new -> sys 3

syntax for global 
(let var1 var2 ... varn)

n-code add: ld, st, ldy, sty   to handle global variable.

ld.a =  M[a]
st.a v = M[a] = v
ldy.a i = M[ M[a] + i ]
sty.a i v = M[ M[a] + i ] = v

DS is relocated when object is loaded in the simulator.  The compiler generate address relative to 0.

both eval4() and evalmp() are updated to work with these new instructions.  (the microprogram is updated).

5 Jan 2005
P. Chongstitvatana