Engineering : Review

[See also: Tempest : Engineering Design]

leaving computers turned-on (electronics, mechanical components(2))
1. earlier types of computer hardware (germanium transistor)
   1. intermediate power voltages: circuits strained, logic defective
      => quick power-on => total system sequenced
   2. transient power capacitively injects semiconductor conductances
      => slower power transients <=> in-circuit surge-suppressors
   3. localized power imbalances drives circuits backwards
      => total power-up, unsequenced, or, signal transients suppressed => slower
   4. hot air currents, after fans off, localize (rise) superheating
      => fans remain 'on' until all circuits cool
   5. thermal cycling mechanically stresses electrical connections
   6. cool components let moisture condense, permeate seals
   7. circuit failures usually unhailed until power-up for use
      => power-up (hours) early for pre-maintenance only => unused time
   8. computer-time costly; and peak-use demands scheduling resolution
2. modern types of computer hardware (silicon integrated circuit)
   1. more robust circuitry can be left untended
      => less need to power-down <=> auto-power-up/down on demand
   2. inter-net connectivity obtains in Earth-global utility
      => 'round-the-clock' nearer-constant activity
   3. plethora of inexpensive computers with cheaper circuit protections
   4. personal use implies more frequent and shorter non-use gaps
      => leave powered-on for readiness
   5. home-use installation/adaptability means peripherals itinerary, and more generalized situational operations/constraints imposed on design flexibility
3. future types of computer hardware
   1. self-monitoring
   2. self-recovering
   3. power-agile
   4. power-bursting

mechanical components last fewer power-up/down cycles than electronics(2)