5.5 RISC and CISC

• Reduced Instruction Set Computers
  • All instructions done in one clock cycle (ideal)
  • All instructions same length
  • May have many (100+) internal registers
  • Executable programs usually (much) larger
  • Data size same.
  • Only simple instructions - No subroutine call or stack instructions
• Complex Instruction Set Computers
  • Some instructions take multiple cycles (some times 100+)
  • All instructions variable length
  • Executable programs compact
  • Data size same.
  • Subroutine call, return, save all registers, & stack instructions
• RISC systems tend to need more memory than CICS