IKI10201 08-Register-transfer Design

1. IKI10201 08-Register-transfer Design Bobby Nazief Semester-I 2005 - 2006 • The materials on these slides are adopted from: • Prof. Daniel Gajski’s transparency for Principles of Digital Design.

2. Road Map Logic Gates &Flip-flops 3 Boolean Algebra 3 6 Finite-StateMachines 6 4 Logic DesignTechniques Sequential DesignTechniques CombinatorialComponents StorageComponents 2 Binary Systems& Data Represent. 7 5 8 Register-TransferDesign 8 Generalized FSM ProcessorComponents 9

3. Review: Simple datapath • Datapath are used for temporary variable storage & operation execution • storage  register file, accumulator • operation execution  ALU • Datapath has 2 types of input/output: • data words (input/output):8, 16, 32, or 64 bits wide • control signals: • input: control words • output: status signals

4. Review: Control unit • Control unit is a sequential circuit that controls datapath’s operations • it receives computer’s instructions (our programs) and status signals (from Datapath) as input • it generates the control words (for Datapath) and other control outputs

5. Design model: high-level block diagram • Processors & ASICs (Application-Specific Integrated Circuit) consist of 2 components: • control unit • datapath

6. Design model: register-transfer-level block diagram

7. Example: one’s counter specification • Basic algorithm: • Data = Inport • Ocount = 0 • Mask = 1 • while Data  0 repeat Temp = Data AND Mask Ocount = Ocount + Temp Data = Data >> 1 • end while • Outport = Ocount

8. FSM with Datapath (FSMD) • FSM: Quintuple <S,I,O,f,h> • S = Q1 x Q2 x ... x Qm • I = A1 x A2 x ... x Ak • O = Y1 x Y2 x ... x Yn • f: S x I  S • h: S x I  O • FSMD = FSM, extended with: • set of variables: V = V1 x V2 x ... x Vq • I = IC x ID • O = OC x OD • next state functions: • fC: S x IC x STAT  S • fD: S x V x ID V • output functions: • hC: S x IC x STAT  OC • hD: S x V x ID OD

9. State & output table Datapath Control Unit

10. State & output table w/ variable assignments Simpler expressions

11. Output = Z State-action table • This table can be used to: • construct state diagram for the control unit • synthesize next-state & output logic • define the datapath components & their connections

12. Algorithmic-State-Machine (ASM) chart • ASM charts: • an alternative graphic form for specifying FSMDs • may suit humans better as they explicitly show the paths from one state to another • ASM chart consists of: • state box • decision box • conditional output box • ASM block

13. ASM’s chart for one’s counter • One’s counter ASM chart using a standard datapath:

14. state-based chart input-based chart ASM’s charts for one’s counter (custom design) • The use of custom datapath may result in fewer components and interconnections. • Examples (in the case of one’s counter design): • state-based (Moore) chart requires 6 states (all variable assignments must be executed unconditionally) • input-based (Mealy) design requires 4 states (variable assignments may be executed conditionally)

15. State-action table & logic equations (state-based)

16. One’s counter circuit (state-based)

17. State-action table & logic equations (input-based)

18. One’s counter circuit (input-based)