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1. Register Transfer and Micro operation NAME : MADHU Roll : 22011A0512 Branch : CSE ( reg )

2. Register Transfer and Micro operations Arithmetic M i c r o - operations Logic Micro-operations Shift Micro-operations Arithmetic Logic Shift Unit Register Transfer Language Register Transfer Bus and Memory Transfers

3. Micro-operations Computer system micro-operations are of four types: Arithmetic micro-operations Logic micro-operations Shift micro-operations Register transfer micro-operations

4. R3  R1 + R2 R3  R1 - R2 R2  R2’ R2  R2 ’ + 1 R3  R1 + R2 ’ + 1 R1  R1 + 1 R1  R1 - 1 Contents of R1 plus R2 transferred to R3 Conte n ts of R1 m inus R2 tra n sferred to R3 Complement the contents of R2 2's complement the contents of R2 (negate) subtraction Increment Decrement The basic ari t h m e t ic m i c r o - o p e r a t i o n s are Addition Subtraction Increment Decrement The ad d i t ional ari t h m e t ic m i c r o -o p e r a t i o n s are Add with carry Subtract with borrow Transfer/Load etc. … Summary of Typical Arithmetic Micro-Operations Arithmetic Micro-operations

5. Logical micro-operations S p ec i fy binary o p erat i o n s on the strings of bits in re g is t ers – Lo g ic m i c r o -o p e r a t i o n s are bi t -wise o p erat i o n s, i.e., they w o rk on the individual bits of data There are, in principle, 16 different logic functions that can be defined over two binary input variables However, most systems only implement four of these – AND (  ), OR (  ), XOR (  ), Complement/NOT The others can be c reated f r om co m bina t i on o f these A B F F 1 F 2 … F 13 F 14 F 15 … 1 1 1 1 … 1 1 1 1 1 … 1 1 1 1 1 … 1 1

6. SHIFT MICROOPERATIONS There are three types of shifts Logical shift Circular shift Arithmetic shift What differentiates them is the information that goes into the serial input A right shift operation Seri al input A left s h ift operation Ser ial input

7. Register transfer language A specific notat i on used t o specify the dig i t a l sys tem i s ca l l e d register transfer language. For any function of the computer, the register transfer language can be used to describe the (sequence of) micro-operations Register transfer language A sy m b o l i c l a n g ua g e A convenient tool for describing the internal organization ofdigital computers Can also be used to facilitate the design process of digital systems

8. Regist e r T ra n s fe r Copying the con t en t s of one re gis ter to ano t her is a re gis ter transfer A register t r ansfer is indic a ted as R2  R1 In this ca se the con t en t s of re gis ter R2 are cop i ed ( l oaded) into register R1 A si m ultan e o u s t r ansfer of all bits f rom the source R1 to the destination register R2, during one clock pulse Note th a t th i s is a non-des t ruct i v e ; i.e. the con t en t s of R1 are not altered by copying (loading) them to R2

9. BASIC SYMBOLS FOR REGISTER TRANSFE R S Symbols Description Examples Cap i t a l l e t t ers & numerals Parenth e ses () Arrow  Colon : Comma , Denotes a register Denotes a part of a register Denot e s tr a nsfer of informat i on Denotes termination of control function Separates two micro-operations MAR, R2 R2(0-7), R2(L) R2  R1 P: A  B, B  A

10. Bus transfer in RTL Depending on whether the bus is to be mentioned explicitly or not, register transfer can be indicated as either R2  R1 or BUS  R1, R2  BUS In the former case the bus is implicit, but in the latter, it is explicitly indicated

11. Memory Transfer AR Memor y unit R ea d W ri t e D a t a in D a t a out Collectively, the memory is viewed at the register level as a device, M. Since it contains multiple locations, we must specify which address in memory we will be using This is done by indexing memory references Memory is usually accessed in computer systems by putting the desired address in a special register, the Memory Address Register ( MAR , or AR ) When memory is accessed, the contents of the MAR get sent to the memory unit’s address lines M