What is RTL?

1. What is RTL? • 1) Describes an action to a register. Whether it be a new load, addition of two registers, transfer from one to the other, etc. • 2) Describes the conditions on which this action will happen.

2. Guidelines: RTL  hardware 1) From the register transfers, determine the values that should be connected to inputs — If a single input may be set to more than one possible value, a multiplexer must be used — The exception to the rule above occurs when all possible inputs come from three-state gates, and only one possible input is not in the high-impedance state 2) From the condition statements, create the control signals that determine Load, Enable, Mode, etc.

3. xyT0 + T1 + y’T2: AR  AR + 1

4. Shown below is a 4-bit shift register, R1, modified from the 8-bit register shown in class. Show the connections necessary to implement the following RTL. x: R1  R1 ; x’y’: R1  SHR(R1) , R1(A)  0 x’y: R1 SHR(R1) , R1(A)  1 What are the conditions for “hold”? X When x is true, then inhibit the shift What are the conditions for “shift”? x’y’ + x’y = x’ If y=1, R1(A) = 1; If y=0, R1(A) = 0 Therefore, R1(A) = y

5. 5v

7. Analysis • Multiplexer enabled when y=0Multiplexer output = 0 when y=1 • x=0 selects R2x=1 selects R1 • z=1 is clearz=0 is load • xy’z’: R5  R1x’y’z’: R5  R2yz’ + z: R5  0 (the same asy + z: R5  0 )

8. Topics for test 2 1) Topics for Test 1 Gates, MSI circuits, IEEE Standard Notation, combining smaller circuits to make larger circuits, ROM, RAM, three-state gates 2) Representation of integers Signed integers, unsigned integers, two’s complement 3) Integer arithmeticOverflow vs. carry 4) Floating point representation mantissa and exponent, range, resolution

9. Topics for test 2 5) Register Transfer Language condition: register tranfer 6) Arithmetic circuits Adder, half-adder, increment 7) RTL  Hardware Given an RTL description, generate the hardware Given the hardware, generate the RTL description Block diagrams and IEEE standard notation