CSU22022, 11th Lecture, Dr. M. Manzke, Page: 1
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:
System state
Input signals
The table on the following slide allows us to
deduce the design of each register:
CSU22022, 11th Lecture, Dr. M. Manzke, Page: 2
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: 3
Register Transfers
From the ASM we can write out the RT
description of the system in terms of:
System state
Input signals
By gathering together the RTs loading each
register we may easily deduce the design of
each register.
CSU22022, 11th Lecture, Dr. M. Manzke, Page: 4
Control Signals for Binary Multiplier
CSU22022, 11th Lecture, Dr. M. Manzke, Page: 5
Sequencing Part of ASM Chart
CSU22022, 11th Lecture, Dr. M. Manzke, Page: 6
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: 7
State Table
Derived from the Sequencing Part of ASM Chart
DM0=IDLE • G + MUL1 • Z
DM1 =MUL0
CSU22022, 11th Lecture, Dr. M. Manzke, Page: 8
Control Unit for Binary Multiplier