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State Machines for Kids A Learning Tool/Toy for Middle School age students

State Machines for Kids A Learning Tool/Toy for Middle School age students. Lee Felsenstein Fonly Institute 2460 Park Blvd. #1 Palo Alto, CA 94306 (650)814-0427 lee@fonlyinstitute.com. Charles Proteus Steinmetz founded the modern field of electrical engineering in the US ca. 1895.

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State Machines for Kids A Learning Tool/Toy for Middle School age students

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  1. State Machines for Kids A Learning Tool/Toy for Middle School age students Lee Felsenstein Fonly Institute 2460 Park Blvd. #1 Palo Alto, CA 94306 (650)814-0427 lee@fonlyinstitute.com

  2. Charles Proteus Steinmetz founded the modern field of electrical engineering in the US ca. 1895 Steinmetz' lectures #1 and #2

  3. Charles Proteus Steinmetz founded the modern field of electrical engineering in the US ca. 1895 Steinmetz' lectures #1 and #2 He delivered a series of three lectures on general electrical engineering which were published.

  4. Charles Proteus Steinmetz founded the modern field of electrical engineering in the US ca. 1895 Steinmetz' lectures #1 and #2 He delivered a series of three lectures on general electrical engineering which were published. The third lecture was republished in the 1950's – the editor omitted the first two because the contents had become “general knowledge” by that time

  5. Our goal is to develop tools that allow the design of state machines to become “general knowledge” - information commonly absorbed by the age of 13.

  6. It is possible to receive a degree in Computer Science without encountering the concept of the bit. Disappearance of the Bit “Increasingly one must fight to include the bit in the CS curriculum' (comment by D. E. Knuth in private discussion).

  7. Learning Toy Characteristics • People learn through play • though most adults cannot admit that. • Most learning toys are physical • tactile input • visual or aural output • easily presentable to others as reinforcement • Software is not well suited as a learning toy • virtual, not easily displayed

  8. SMLD Design Goals • Reasonable cost • purchased by parent for child • long life time • Immediate response and reinforcement • take an action, see the response at once • pushbutton clocking • Capable of wide range of configurations • Interconnectable and interoperable

  9. SMLD operating goals • Require symbolic logic representation for more than trivial results • origin of software • simple syntax for Boolean and sequential operations • Offer rapid reinforcement • Encourage group learning • Permit individual learning • Support creation of meaningful tools • My first PDP-8

  10. SMLD operating goals • Require symbolic logic representation for more than trivial results • Origin of software • Simple syntax for Boolean and sequential operations • Offer rapid reinforcement • Encourage group learning • Permit individual learning • Support creation of meaningful tools • My first PDP-8

  11. Registered State Machine • 8 latches • D type – common clock • D input is OR of 8 terms • Terms are ANDs of inputs and outputs • upright and inverted • AND functions defined by diodes inserted at matrix crosspoints • tweezer programming • LEDs indicate latch output and term states

  12. Pedagogy • Understand logic functions • NOT (output opposite of input) • OR (output if ANY input active) • AND (output if ALL inputs active) • Understand latch (sequential) function • Output dependent on clock occurrence • Output independent of input at all other times • Understand symbolic representation of logic • ! (inversion), & (OR), # (AND), : (sequentiality) • Latch equation Q := D

  13. Pedagogy, continued • Each step illustrated with interactive trials • Quick progress to first accomplishment • toggle operation Q := !Q • push the button, watch the LED change • none of your friends can do this! • now, make all the LEDs do it! • Try any variation – it can't be damaged

  14. The Matrix • 8 rows of 33 holes – 32 input columns per row • 8 inputs + 8 inverse (INn, !INn) • 8 register outputs + 8 inverse (Qn, !Qn) • Select column by MELF diode in hole • Selected terms are ANDed together • All rows are ORed to form input to register

  15. !INB INB !Q !INA INA Q & & & & & & PU OR A Q D & & & & & & Q PU B LATCH Connect a diode at a & point to include that signal in an AND function !Q CLK PU = resistive pull-up SMLD ELEMENTAL LOGIC BLOCK SCHEMATIC

  16. SMLD Product – Register Board • PCB 4” x 8” • 8 LEDs on front edge – output status • 2 pushbutton switches – Clock, Reset • 8 card edge connectors for matrix boards • 32-pin Eurocard connector at rear edge • Unregulated DC power input jack • DIP switch selects combinatorial vs. registered

  17. SMLD Matrix Board • 8 daughter cards – one per bit – 1.75” H x 4” L • Top removes with 1/4 T fasteners • Mini-MELF diodes placed in matrix holes on block • Grooves allow tweezer access • 8 LEDs at edge display state of terms • Conductive gaskets absorb component variations

  18. Exercises • Make a bit toggle with the clock • no Boolean logic required • Decode a binary number (term LEDs - AND) • OR of terms to latch • Two-bit counter (modulo 4 – uses toggle) • Two-bit counter (modulo 3) • Ring counter (walk 1 bit down 8 latches) • Johnson counter (fill 8 bits, then empty)

  19. 8-bit State Machine • 256 states - Moore type • Logic level outputs can drive simple effectors • Solenoids – high current requires driver transistor • Robot actions • Anything using digital control inputs • Switch inputs • Photosensors, keypads, joysticks, analog comparators (with hysteresis) • External clocks – up to 1 MHz

  20. Multi-card Operation • Clock and Reset can be directly driven from Eurocard connector • 8 outputs (Q0:7) • 8 inputs (IN0:7) • Clock (CLK) – max. rate ~1MHz • Reset (RST) • With a memory board, working minicomputers (PDP-8/S e.g.) can be built from about 20 boards.

  21. “How is this different from a microprocessor? • Tactile/visual/experimental tool for understanding how bits work • Mental models are very small and easy to understand • Building block for computers • Very short path to reinforcement

  22. Future • SMLDs work together, so kids can form larger projects together • ~20 kids with SMLDs and a memory board can build a PDP-8/S minicomputer • Peripherals - • sensors and effectors • printer • communications • buildable and understandable by kids 11-14

  23. Status • SMLD board set designed and in layout stages • 2-bit prototype (exhibited) has been tried in 4 event with 10 – 14 year old kids • 14 pages of courseware written and edited based on proto trial • Seeking partners in bringing SMLD to market

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