System state Input signals
Shift-and-Add Multiplication ASM
Note the concatenation notation
From the ASM we can write out the RT description of the system in terms of:
The table on the following slide allows us to deduce the design of each register:
CSU22022, 11th Lecture, Dr. M. Manzke, Page: 1
Control and Sequencing
Two distinct aspects in control unit design Control of micro-operations
Sequencing
We separate the two aspects by providing:
A state table
Defines signals in terms of states and inputs
A simplified ASM chart Represents only state transitions
CSU22022, 11th Lecture, Dr. M. Manzke, Page: 2
System state Input signals
Register Transfers
From the ASM we can write out the RT description of the system in terms of:
By gathering together the RTs loading each register we may easily deduce the design of each register.
CSU22022, 11th Lecture, Dr. M. Manzke, Page: 3
Control Signals for Binary Multiplier
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Sequencing Part of ASM Chart
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Sequence Register and Decoder
This method uses:
Sequence Register:
That holds control states
Register with n flop-flops has 2n states
Decoder
Provides output signal for each state. An n-to-2n decoder has 2n outputs
CSU22022, 11th Lecture, Dr. M. Manzke, Page: 6
DM0=IDLE • G + MUL1 • Z DM1 =MUL0
State Table
Derived from the Sequencing Part of ASM Chart
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Control Unit for Binary Multiplier
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