CS 61C L20 Synchronous Digital Systems (1) Wawrzynek Spring 2006 © UCB3/6/2006John Wawrzynek(www.cs.berkeley.edu/~johnw)www-inst.eecs.berkeley.edu/~cs61c/CS61C – Machine StructuresLecture 20 - Introduction toSynchronous Digital SystemsCS 61C L20 Synchronous Digital Systems (2) Wawrzynek Spring 2006 © UCBBelow 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;}° Assembly language program (for MIPS)swap: sll $2, $5, 2add $2, $4,$2lw $15, 0($2)lw $16, 4($2)sw $16, 0($2)sw $15, 4($2)jr $31° Machine (object) code (for MIPS) 000000 00000 00101 0001000010000000 000000 00100 00010 0001000000100000 . . .C compilerassembler?CS 61C L20 Synchronous Digital Systems (3) Wawrzynek Spring 2006 © UCB61CWhat are “Machine Structures”?Coordination of many levels of abstractionI/O systemProcessorCompilerOperatingSystem(MacOS X)Application (Netscape)Digital DesignCircuit DesignInstruction Set ArchitectureDatapath & Control transistorsMemoryHardwareSoftwareAssemblerISA is an important abstraction level:contract between HW & SWCS 61C L20 Synchronous Digital Systems (4) Wawrzynek Spring 2006 © UCBSynchronous Digital SystemsSynchronous:• Means all operations are coordinated bya central clock. (It keeps the beat of thesystem).Digital:• Mean all values are represented bydiscrete values• Electrical signals are treated as 1’s and0’s and grouped together to form words.The hardware of a processor, such as the MIPS, is anexample of a Synchronous Digital SystemCS 61C L20 Synchronous Digital Systems (5) Wawrzynek Spring 2006 © UCBLogic Design° Next 4 weeks: we’ll study how a modernprocessor is built; starting with basicelements as building blocks.° Why study hardware design?• Understand capabilities and limitations ofhardware in general and processors inparticular.• What processors can do fast and what theycan’t do fast (avoid slow things if you want yourcode to run fast!)• Background for more detailed hardware courses(CS 150, CS 152)• There is just so much you can do withprocessors. At some point you may need todesign your own custom hardware.CS 61C L20 Synchronous Digital Systems (6) Wawrzynek Spring 2006 © UCBPowerPC Die PhotographLet’s lookcloser…CS 61C L20 Synchronous Digital Systems (7) Wawrzynek Spring 2006 © UCBTransistor Circuit Rep. vs. Block diagram° Chips is composed of nothing buttransistors and wires.° Small groups of transistors form usefulbuilding blocks.° Block are organized in a hierarchy to buildhigher-level blocks: ex: adders.CS 61C L20 Synchronous Digital Systems (8) Wawrzynek Spring 2006 © UCBThe Clock SignalCS 61C L20 Synchronous Digital Systems (9) Wawrzynek Spring 2006 © UCBSignals and WaveformsCS 61C L20 Synchronous Digital Systems (10) Wawrzynek Spring 2006 © UCBSignals and Waveforms: GroupingCS 61C L20 Synchronous Digital Systems (11) Wawrzynek Spring 2006 © UCBSignals and Waveforms: Circuit DelayCS 61C L20 Synchronous Digital Systems (12) Wawrzynek Spring 2006 © UCBType of Circuits° Synchronous Digital Systems are madeup of two basic types of circuits:° Combinational Logic (CL) circuits• Our previous adder circuit is an example.• Output is a function of the inputs only.• Similar to a pure function in mathematics,y = f(x). (No way to store information fromone invocation to the next. No sideeffects)° State Elements: circuits that storeinformation.CS 61C L20 Synchronous Digital Systems (13) Wawrzynek Spring 2006 © UCBCircuits with STATE (e.g., register)CS 61C L20 Synchronous Digital Systems (14) Wawrzynek Spring 2006 © UCBAnd in conclusion…° ISA is very important abstraction layer• Contract between HW and SW° Clocks control pulse of our circuits° Voltages are analog, quantized to 0/1° Circuit delays are fact of life° Two types of circuits:• Stateless Combinational Logic (&,|,~)• State circuits (e.g.,
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