9/18 bit Cpu May 16,2009

This is a 9/18 computer about 1978 ish. This one will have a
a real front panel / switches /leds and single instruction step
operation. CPU,64Kb memory+Boot Rom and a uart will be standard.
The cpu is three 128 cell CPLD's and one 128 cell CPLD for the control logic
and one 64 cell CPLD for data bus swap and buffering.

 With a 4 MHZ clock,instruction times are 1.25 us or 2.50 us long.

Registers  A,C,X,S    C is A with carry
MQ is swap with AC only for extended use
Index  0,#,B/S,X    
   B-ase  S&770000 +offset
   S-tack  S+ - offset
   .

8 7 6   5 4 3   2 1 .  9 8 7   6 5 4   3 2 1
_ _ _   _ _ _   _ _ _  _ _ _   _ _ _   _ _ _ 
.op.    J I X   b A C  # # #   # # #   # # #  opcode normal, immedate short
# # #   # # #   # # #  # # #   # # #   # # #  immedate word


OP:J=1		j=0
  jmp/scc 	memory
0 X<0		and
1 Z		xor
2 S     	or   
3 S|Z   	ld
4 C    		add/adc
5 C|Z   	sub/sbc
6 lea  		st
7 opr  		jmp/jsv

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