nanoFabric Chang Seok Bae nanoFabric nanoFabric : an array of connect nanoBlocks  nanoBlock : logic block that can be  progammed to implement Boolean.

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Transcript nanoFabric Chang Seok Bae nanoFabric nanoFabric : an array of connect nanoBlocks  nanoBlock : logic block that can be  progammed to implement Boolean.

nanoFabric
Chang Seok Bae
nanoFabric
nanoFabric : an array of connect nanoBlocks
 nanoBlock : logic block that can be

progammed to implement Boolean function
and switches to route signals
 Using CAEN (chemically assembled
electronic nanotechnology) requires new
computer architecture
 Next: fabrication/architectural implication
and overview on the architecture
Fabrication and Architectureal
Implications

Plausible fabrication process
Wires of different types are constructed through
chemical self-assembly
 Aligns groups of wires
 Silicon-based die


Self-assembly (alignment) restriction
A post-fabrication configuration
 Bypassing defect density

Fabrication and Architectureal
Implications (cont)

Two-terminal device (diode-resistor logic)
Three-terminal device is unsuitable with
inexpensive chemical assembly
 No inverter: output and its complement


Signal restoration and registers
Lack of transistor
 CMOS: density problem and speed down
 Molecular latch: composed of a wire with two
inline NDR (negative difference registers) at
either end

NanoFabric architecture
nanoBlock
 nanoBlock connectivity
 Scalability
 Defect Tolerance
 Configuration

nanoBlock

Fundamental unit

MLA (molecular
logic array) :
functionality of
block
 Latches
 I/O area: connect
the nanoBlock to
its neighbors
nanoBlock (cont)

MLA
Two orthogonal sets of
wires: when configured
to be “on”, act as
diodes
 Benefit: construted by
direct assembly
 Drawback: signal
degrading, so
molecular latch is used

nanoBlock Connectivity
Fabrication constrain bring
each side of block to have
inputs or output but not
both: one diagonal
 Switch block: input/output
overlap

Scalability

Arrangement of
clusters and long-wires
Routability of netlists as
the number of
components increasing
 Configuration time to
be remained due to
parallel configuration

Defect Tolerance

Defect-tolerant nature



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Regularity: choose where particular function is
implemented
Configurability: pick one component (nanowire, parts of
nanoBlock) which implements particular circuit
Fine-grained nature: reduce the impact of a defect to a
small portion of the fabric, which enriches
interconnection overhead
Key difficulty:


impossible to test the individual components in isolation
Teramac: inconjuction with an outside host to test itself
Defect Tolerance (cont)

Defect mapping process

Phase I: no known fault-free regions
 Basic
tester implemented in CMOS
 Host computer configures testers

Phase II: After a sufficient number of
functioning resources discovered
 Already
tested area of the fabric acts as a host for
testing the remainder
 For very large devices, many parallel independent
device used
Configuration

Molecular switch :


high voltage outside the normal operating range
Configuration
Fabric scale: Fabric is design so that clusters
can be programmed in parallel
 Cluster scale: configuring one nanoBlock per
cluster due to CMOS overhead
 nanoBlock scale: Accessing each nanowire
separately not in space but in time dimension

SAM simulation
To exploit the advantage of nanoFabric,
SAM (a split-phase abstract machines) is
proposed and simulated.
 Comment: this simulation is approached at
highest level away from the circuit
constraints.

Conclusion
Even though this approach exploit the
parallel nature of chemical assembly, finegrained style brings high complexity of
configuration to implement functionality or
fault tolerance
 There are still many challenges left in
creating functional computing device
