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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
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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
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
7-1 Register and Load Enable Register with load enable by clock gating
7-1 Register and Load Enable Register with load enable directly through input
7-2 Register transfer • 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
7-2 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
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
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
7-3 Register Transfer Operations More register transfer operation executed at the same time: K3: R2 ←R1, R1 ←R2
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
Arithmetic Microoperations Fig. 7.6 Implementation The control variable X selects the operation, and the control variable K1 loads the result in to R1.