Abstraction And Technology 1 Comp 411 – Fall /28/06 Computer Abstractions and Technology 1. Layer Cakes 2. Computers are translators 3. Switches and Wires (Read Chapter 1)

Abstraction And Technology 2 Comp 411 – Fall /28/06 Computers Everywhere ∙The computers we are used to  Desktops  Laptops  Embedded processors Cars Mobile phones Toasters, irons, wristwatches, happy-meal toys

Abstraction And Technology 3 Comp 411 – Fall /28/06 Compiler for (i = 0; i < 3; i++) m += i*i; Assembler and Linkeraddi $8, $6, $6 sll $8, $8, 4 CPU Module ALU AB Cells A B CO CI S FA A Computer System ∙What is a computer system? ∙Where does it start? ∙Where does it end? Gates Transistors

Abstraction And Technology 4 Comp 411 – Fall /28/06 Computer Layer Cake ∙Applications ∙Systems software ∙Shared libraries ∙Operating System ∙Hardware – the bare metal Hardware Operating System Libraries Systems S/WApps Computers are digital Chameleons

Abstraction And Technology 5 Comp 411 – Fall /28/06 Computers are Translators ∙User-Interface (visual programming) ∙High-Level Languages  Compilers  Interpreters ∙Assembly Language ∙Machine Language x:.word 0 y:.word 0 c:.word lw$t0, x addi$t0, $t0, -3 lw$t1, y lw$t2, c add$t1, $t1, $t2 mul$t0, $t0, $t1 sw$t0, y int x, y; y = (x-3)*(y )

Abstraction And Technology 6 Comp 411 – Fall /28/06 Computers are Translators ∙User-Interface (visual programming) ∙High-Level Languages  Compilers  Interpreters ∙Assembly Language ∙Machine Language x:.word 0 y:.word 0 c:.word lw$t0, x addi$t0, $t0, -3 lw$t1, y lw$t2, c add$t1, $t1, $t2 mul$t0, $t0, $t1 sw$t0, y 0x x x x x x x706d6f43

Abstraction And Technology 7 Comp 411 – Fall /28/06 Why So Many Languages? ∙Application Specific  Historically: COBOL vs. Fortran  Today: C# vs. Java Visual Basic vs. Matlab ∙Code Maintainability  High-level specifications are easier to understand and modify ∙Code Reuse ∙Code Portability ∙Virtual Machines

Abstraction And Technology 8 Comp 411 – Fall /28/06 Under the Covers ∙Input ∙Output ∙Storage ∙Processing  Datapath  Control

Abstraction And Technology 9 Comp 411 – Fall /28/06 Under the Covers ∙Input ∙Output ∙Storage ∙Processing  Datapath  Control

Abstraction And Technology 10 Comp 411 – Fall /28/06 Under the Covers ∙Input ∙Output ∙Storage ∙Processing  Datapath  Control Cathode Ray Tube (CRT) The “last vacuum tube” Now nearing extinction

Abstraction And Technology 11 Comp 411 – Fall /28/06 Under the Covers ∙Input ∙Output ∙Storage ∙Processing  Datapath  Control Liquid Crystal Displays (LCDs)

Abstraction And Technology 12 Comp 411 – Fall /28/06 Under the Covers ∙Input ∙Output ∙Storage ∙Processing  Datapath  Control

Abstraction And Technology 13 Comp 411 – Fall /28/06 Under the Covers ∙Input ∙Output ∙Storage ∙Processing  Datapath  Control

Abstraction And Technology 14 Comp 411 – Fall /28/06 Under the Covers ∙Input ∙Output ∙Storage ∙Processing  Datapath  Control Intel Pentium III Xeon

Abstraction And Technology 15 Comp 411 – Fall /28/06 Implementation Technology ∙Relays ∙Vacuum Tubes ∙Transistors ∙Integrated Circuits  Gate-level integration  Medium Scale Integration (PALs)  Large Scale Integration (Processing unit on a chip)  Today (Multiple CPUs on a chip) ∙Nanotubes?? ∙Quantum-Effect Devices??

Abstraction And Technology 16 Comp 411 – Fall /28/06 open closed Implementation Technology ∙Common Links? ∙A controllable switch ∙Computers are wires and switches open control

Abstraction And Technology 17 Comp 411 – Fall /28/06 Chips ∙Silicon Wafers  Chip manufactures build many copies of the same circuit onto a single wafer. Only a certain percentage of the chips will work; those that work will run at different speeds. The yield decreases as the size of the chips increases and the feature size decreases.  Wafers are processed by automated fabrication lines. To minimize the chance of contaminants ruining a process step, great care is taken to maintain a meticulously clean environment.

Abstraction And Technology 18 Comp 411 – Fall /28/06 Field Effect Transistors (FETs) ∙Modern silicon fabrication technology is optimized to build a particular type of transistor. The flow of electrons from the source to the drain is controlled by a gate voltage. SourceDrainGate Bulk n+ p I DS = 0 V DS

Abstraction And Technology 19 Comp 411 – Fall /28/06 Chips ∙Silicon Wafers Metal 2 M1/M2 via Metal 1 Polysilicon Diffusion Mosfet (under polysilicon gate) IBM photomicrograph (Si has been removed!)

Abstraction And Technology 20 Comp 411 – Fall /28/06 How Hardware WAS Designed ∙20 years ago  I/O Specification Truth tables State diagrams  Logic design  Circuit design  Circuit Layout

Abstraction And Technology 21 Comp 411 – Fall /28/06 How Hardware IS Designed ∙Today (with software) ∙High-level hardware specification languages  Verilog  VHDL

Abstraction And Technology 22 Comp 411 – Fall /28/06 Reconfigurable Chips ∙Programmable Array Logic (PALs)  Fixed logic / programmable wires ∙Field Programmable Gate Arrays (FPGAs)  Repeated reconfigurable logic cells

Abstraction And Technology 23 Comp 411 – Fall /28/06 Death of Silicon Diversity ∙In the future will there be more or fewer types of chips? ∙Programmability = Flexibility ∙One chip can be programmed to perform many functions ∙An ultra-flexible architecture might be designed to emulate any function required ∙High-volumes might compensate for wasted area ∙Computers are this ultimate circuit type ∙How many types of chips do we need?  Memory chips  Logic Chips  Potato Chips (credit Anant Agrawal)

Abstraction And Technology 24 Comp 411 – Fall /28/06 Next Time ∙Computer Representations ∙How is X represented in computers?  X = text  X = numbers  X = anything else ∙Encoding Information