In this lecture we see how normal "flow of control" can be hijacked for alternative purposes.

1. The biological virus.
   1. Little more than DNA and/or RNA and a shell or capsid.
   2. Potentially 25 nm in diameter.
   3. Enters the cell and hijacks the synthetic machinery of the cell.
   4. Toggles host genes and expresses its own.
   5. Reproduces rapidly, potentially killing the host (or vector).
2. The computer virus.
   1. Prelude: the self reproducing code (see here for instructions and here for code).
   2. Notion of the "locus of control".
   3. The interrupt vector.
   4. The Mac and the PC.
   5. Memory protection.
   6. Many other mechanisms: the PATH variable in unix

Resources needed for this class:

• The clone program. What features of this program make it autocatalytic? How does it react?
• Work by Belcher at MIT on nanoscale batteries and nanoscale wire assembly using viruses.

Resources to think about for next class:

• Chip Walter's epilog on Cyber Sapiens from Thumbs, Toes, and Tears.

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