1. REGISTER TRANSFER LANGUAGE MICROOPERATIONS

2. TODAY OUTLINES Logic Microoperations Shift Microoperations

3. LOGIC MICROOPERATIONS

4. Specify binary operations on the strings of bits in registers ◦ Logic microoperations are bit-wise operations, i.e., they work on the individual bits of data ◦ useful for bit manipulations on binary data ◦ useful for making logical decisions based on the bit value The symbols for the four basic logic operations are: ◦ OR (  ), ◦ AND (  ), ◦ XOR (  ), ◦ Complement/NOT Logic Microoperations

5. LOGIC MICROOPERATIONS v OR (SETS Bits) ^ AND (CLEARS Bits)  XOR (Complement Bits, 2 Sources) NOT (Complement Bits, 1 Source) Example:R3R4 v R6 Example:R2DR ^ R1 Example:PCPC  DR Example:R6R1

6. LOGIC MICROOPERATIONS Example: Let R1 = 10101010 and R2 = 11110000 After the operations, R0 becomes:

7. HARDWARE IMPLEMENTATION OF LOGIC MICROOPERATIONS Function table Logic Microoperations B A S S F 1 0 i i i 0 1 2 3 4 X 1 MUX Select 0 0 F = A  B AND 0 1 F = A  B OR 1 0 F = A  B XOR 1 1 F = A’ Complement S 1 S 0 Output  -operation

8. APPLICATIONS OF LOGIC MICROOPERATIONS Logic microoperations can be used to manipulate individual bits or a portions of a word in a register Logic microoperations can change bit values, clear a group of bits, or insert new bit values into a register.

9. AND microoperation Used for clearing one or more bits in a register to 0. Boolean equations: ◦ X 0 = 0 When ANDed with 0, binary variable X produces 0. ◦ X 1 = X When ANDed with 1, binary variable X remains unchanged.

10. AND microoperation Example: 10101101 10101011R1(data) 00000000 11111111R2(mask) 00000000 10101011R1  R1 ^ R2 AND operation: ◦ Selectively clear bits of a register ◦ Masking out the bits X 0 = 0 X 1 = X R1 : High-order byte = Clear Low-order byte = Unchanged R1 : High-order byte = Clear Low-order byte = Unchanged

11. OR microoperation Used to set one or more bits in a register. Boolean equations: ◦ X + 1 = 1 When ORed with 1, binary variable X produces a 1. ◦ X + 0 = X When ORed with 0, binary variable X remains unchanged.

12. OR microoperation Example: 10101101 10101011R1(data) 11111111 00000000 R2(mask) 11111111 10101011R1  R1 v R2 OR operation: ◦ Selectively set bits of a register X + 1 = 1 R1: High-order byte = Set to 1’s Low-order byte = Unchanged R1: High-order byte = Set to 1’s Low-order byte = Unchanged X + 0 = X

13. XOR microoperation Used to complement one or more bits in a register. Boolean equations: ◦ X  1 = X When XORed with 1, binary variable X complemented. ◦ X  0 = X When XORed with 0, binary variable X remains unchanged.

14. XOR microoperation Example: 10101101 10101011R1(data) 11111111 00000000 R2(mask) 01010010 10101011R1  R1  R2 XOR operation: ◦ Selectively complement bits of a register R1: High-order byte = Complemented Low-order byte = Unchanged R1: High-order byte = Complemented Low-order byte = Unchanged X  0 = X X  1 = X

15. SHIFT MICROOPERATIONS

16. Shift microoperations are used for: ◦ Lateral movement of data. ◦ Serial transfer of data. ◦ Manipulating the contents of registers in arithmetic, logical, and control operations. Left shift:toward the MSB Right shift:toward the LSB MSB 76543210 LSB

17. 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/incoming bit Shift Microoperations Serial input A right shift operation A left shift operation Serial input LSB MSB

18. SHIFT MICROOPERATIONS Shift Microoperations Serial input A right shift operation A left shift operation Serial input LSB MSB

19. SHIFT MICROOPERATIONS In RTL, string of letters are used to specify 1-bit shift operations: ◦ Shift left :sl ◦ Shift right :sr

20. LOGICAL SHIFT Assume the serial input/incoming bit to the shift is a 0. A right shift operation: A left shift operation: Example of Shifts: Shift Microoperations 0 0 TypeSymbolic Source R2After Shift: DesignationDestination R1 Shift Left R1 sl R21001111000111100 Shift Right R1 sr R21110010101110010

21. SHIFT MICROOPERATIONS Example 1: Let R2 = 11001001 After the Shift operation, R1 becomes: Note: These shifts "zero fill". Sometimes a separate flip-flop is used to provide the data shifted in, or to “catch” the data shifted out.