2. Historical Progression of Computer Hardware and Software

• Hardware
  1. mechanical (pre-computer)
  2. electro-mechanical (hardwired with mechanical toggle switches)
  3. vacuum tube (reduced hardwiring and mechanical toggles)
  4. transistors (further reduction in hardwiring / mechanical toggles)
  5. integrated circuits, LSI, VLSI (minimal hardwiring / mechanical toggles)
     • issues of speed, heat, density, power consumption, reliability
     • RAM - Static (SRAM) & Dynamic (DRAM)
     • ROM - Programmable (PROM); Erasable (EPROM); Electronically Erasable (EEPROM)

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• Software
  1. fixed application (no software)
  2. direct load / wiring of application
  3. re-usable "subroutines" (typically on hand-wired plug boards)
  4. program loader (toggled routine / plug board) to load application to RAM
  5. operating system auto-loaded from secondary storage; "batch" processing
  6. multi-programming: overlapping concurrent IO operations with processing; "batch" processing
  7. interactive / multi-user / on-line processing
  8. virtual tasking
  9. distributed processing