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Control Subsystem

  By monitoring the conditions issued by the data subsystem and activating appropriate control signals, the control subsystem is able to control the data subsystem. This results in an implementation of the algorithm.

The control subsystem is a state machine with state diagram shown in Figure 90 (control signal outputs not shown). Its operation table is as follows:

PS	NS	ldX	ldY	selX	selY
wait	setup if start=1	0	0	$\phi$	$\phi\phi$
	wait if start=0
setup	abs val	1	1	0	00
abs val	chk iter	0	1	$\phi$	01
chk iter	iterate if k=1	0	0	$\phi$	$\phi\phi$
	multiply if k=0
iterate	chk iter	1	1	1	10
multiply	wait	0	0	$\phi$	$\phi\phi$

The controller state machine can be implemented using any of the standard methods we have learned; e.g. with flip flops and combinational logic.

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