2. Overview Part 1 - Registers, Microoperations and Implementations
Registers and load enable
Register transfer operations
Microoperations - arithmetic, logic, and shift
Microoperations on a single register
Multiplexer-based transfers
Shift registers
Part 2 - Counters, Register Cells, Buses, & Serial Operations
Part 3 – Control of Register Transfers

3. Registers
Register
a collection of binary storage elements
included a set of flip-flop
n-bit register store n-bit binary information
Frequently used to perform simple data storage and data movement and processing operations

4. 7-1 Register and Load Enable
Register with load enable by clock gating
States: 22 = 4
Input Combinations: 22 = 4
Output Combinations: 22 = 4
Y = A
A(t+1) = IN
Moore
States = 2n
Input Combinations = 2n
Output Combinations = 2n

5. 7-1 Register and Load Enable
Register with load enable directly through input

6. 7-2 Register transfer Datapath: performs data-processing operations
Large digital systems are hard to be designed by using state table in Chap. 5
Large digital systems are often designed by modular, hierarchical approach
Large digital systems are partitioned into two types of modules
Datapath: performs data-processing operations
Control unit: determine the sequence of those operations

7. 7-2 Register transfer
The registers are assumed to be basic components of the digital system
Register transfer operation: movement on the data stored in register and the processing performed on the data
Three basic components
The set of registers in digital systems
The operations performed on the data
Control on the sequence of operations

8. 7-3 Register Transfer Operations
Notation for register: uppercase letters (sometime followed by numbers)
AR: address register
PC: program counter
IP: instruction register
R2: the register 2

9. 7-3 Register Transfer Operations
Data transfer from a register to another one
R2 ←R1
Data transfer with conditions
If (K1=1) then (R2 ←R1)
K1: R2 ←R1
Hardware implementation

10. 7-3 Register Transfer Operations
More register transfer operation executed at the same time:
K3: R2 ←R1, R1 ←R2

11. 7-4 A note for VHDL and Verilog

12. 7-5 Microoperation
An elementary operations performed on data stored in registers or in memory.
Transfer
Arithmetic
Logic: perform bit manipulation on data in register
Bitwise AND, Bitwise OR ….
Shift

13. Arithmetic Microoperations

14. Arithmetic Microoperations
The control variable X selects the operation, and the control variable K1 loads the result in to R1.
Fig. 7.6 Implementation