state machines for kids a learning tool/toy for middle school age students
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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 [email protected]. Charles Proteus Steinmetz founded the modern field of electrical engineering in the US ca. 1895. - PowerPoint PPT PresentationTRANSCRIPT
State Machines for Kids A Learning Tool/Toy
for Middle School age students
Lee Felsenstein
Fonly Institute2460 Park Blvd. #1Palo Alto, CA 94306(650)814-0427
Steinmetz' lectures #1 and #2
Charles Proteus Steinmetz founded the modern field of electrical engineering in the
US ca. 1895
Steinmetz' lectures #1 and #2
Charles Proteus Steinmetz founded the modern field of electrical engineering in the
US ca. 1895
He delivered a series of three lectures on general electrical engineering which were published.
Steinmetz' lectures #1 and #2
Charles Proteus Steinmetz founded the modern field of electrical engineering in the
US ca. 1895
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
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.
Disappearance of the Bit
It is possible to receive a degree in Computer Science without encountering the concept
of the bit.
“Increasingly one must fight to include the bit in the CS curriculum' (comment by D. E. Knuth in private discussion).
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
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
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
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
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
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
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
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
D
CLK
Q
!Q
ORA
B
INB
& & & & & && & & & & &
Q
!Q
Connect a diode at a & point to include that signal in an AND function
PU
PU
PU = resistive pull-up
!INB
!INA
LATCH
INA
Q
SMLD ELEMENTAL LOGIC BLOCK SCHEMATIC
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
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
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)
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
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.
“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
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
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