inst eecs berkeley edu cs61c CS61C Machine Structures Lecture 20 Introduction to Synchronous Digital Systems 2004 10 15 Lecturer PSOE Dan Garcia www cs berkeley edu ddgarcia Great new PC HW OQO model 01 is the new lightest coolest fullyfunctional PC on the block 1GHz 20GB drive 256MB RAM wireless color display thumb keyboard oqo com which slides out Small light CS 61C L20 Introduction to Synchronous Digital Systems 1 Garcia Fall 2004 UCB What are Machine Structures Application Netscape Compiler Software Hardware Assembler Operating System MacOS X Processor Memory I O system 61C Instruction Set Architecture Datapath Control Digital Design Circuit Design transistors Coordination of many levels of abstraction We ll investigate lower abstraction layers contract between HW SW CS 61C L20 Introduction to Synchronous Digital Systems 2 Garcia Fall 2004 UCB Below the Program High level language program in C swap int v int k int temp temp v k v k v k 1 v k 1 temp C compiler Assembly language program for MIPS swap sll add lw lw sw sw jr 2 5 2 2 4 2 15 0 2 16 4 2 16 0 2 15 4 2 31 assembler Machine object code for MIPS 000000 00000 00101 0001000010000000 000000 00100 00010 0001000000100000 CS 61C L20 Introduction to Synchronous Digital Systems 3 Garcia Fall 2004 UCB Logic Design Next 2 weeks we ll study how a modern processor is built starting with basic logic elements as building blocks Why study logic design Understand what processors can do fast and what they can t do fast avoid slow things if you want your code to run fast Background for more detailed hardware courses CS 150 CS 152 CS 61C L20 Introduction to Synchronous Digital Systems 4 Garcia Fall 2004 UCB Logic Gates Basic building blocks are logic gates In the beginning did ad hoc designs and then saw patterns repeated gave names Can build gates with transistors and resistors Then found theoretical basis for design Can represent and reason about gates with truth tables and Boolean algebra Assume know truth tables and Boolean algebra from a math or circuits course Section B 2 in the textbook has a review CS 61C L20 Introduction to Synchronous Digital Systems 5 Garcia Fall 2004 UCB Physical Hardware Let s look closer CS 61C L20 Introduction to Synchronous Digital Systems 6 Garcia Fall 2004 UCB Gate level view vs Block diagram A 0 0 1 1 B 0 1 0 1 CS 61C L20 Introduction to Synchronous Digital Systems 7 C 1 1 1 0 Garcia Fall 2004 UCB Signals and Waveforms Clocks CS 61C L20 Introduction to Synchronous Digital Systems 8 Garcia Fall 2004 UCB Signals and Waveforms Adders CS 61C L20 Introduction to Synchronous Digital Systems 9 Garcia Fall 2004 UCB Signals and Waveforms Grouping CS 61C L20 Introduction to Synchronous Digital Systems 10 Garcia Fall 2004 UCB Signals and Waveforms Circuit Delay CS 61C L20 Introduction to Synchronous Digital Systems 11 Garcia Fall 2004 UCB Combinational Logic Complex logic blocks are built from basic AND OR NOT building blocks we ll see shortly A combinational logic block is one in which the output is a function only of its current input Combinational logic cannot have memory e g a register is not a combinational unit CS 61C L20 Introduction to Synchronous Digital Systems 12 Garcia Fall 2004 UCB Circuits with STATE e g register CS 61C L20 Introduction to Synchronous Digital Systems 13 Garcia Fall 2004 UCB Administrivia Midterm coming up on Monday 7pm in 1 Pimintel Heard this enough yet CS 61C L20 Introduction to Synchronous Digital Systems 14 Garcia Fall 2004 UCB Peer Instruction ABC A SW can peek at HW past ISA abstraction boundary for optimizations 1 FFF B SW can depend on particular HW implementation of ISA C Timing diagrams serve as a critical debugging tool in the EE toolkit CS 61C L20 Introduction to Synchronous Digital Systems 15 2 3 4 5 6 7 8 FFT FTF FTT TFF TFT TTF TTT Garcia Fall 2004 UCB And in conclusion ISA is very important abstraction layer Contract between HW and SW Basic building blocks are logic gates Clocks control pulse of our circuits Voltages are analog quantized to 0 1 Circuit delays are fact of life Two types Stateless Combinational Logic State circuits e g registers CS 61C L20 Introduction to Synchronous Digital Systems 16 Garcia Fall 2004 UCB
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