14. Computer Generations 1st 2nd 3rd 4th 5th Timeframe 1951-1958 1959-1964 1965-1974 1975-1989 1990-present Circuit Components Vacuum Tubes Transistors Integrated Circuits (IC) Large-scale IC (LSI) Very Large IC (VLSI) Memory Capacity 4,000 Bits 32,000 Bits 128,000 Bits 100 Million Bits Unlimited Data Input Hard Wired Program in computer Punch Cards Keyboard Entry Read Programs off Disk CDROM, Optical Disk