Generations of Computer: Second Generation (1956 to 1963): Using Transistors

We will discuss the generations of computer in terms of

• The technology used by them (hardware and software),
• computing characteristics (speed, i.e.,number of instructions executed per second),
• physical appearance, and
• their applications.

Second Generation (1956 to 1963): Using Transistors

• Hardware Technology Transistors replaced the vacuum tubes of the first generation of computers. Transistors allowed computers to become smaller, faster, cheaper, energy efficient and reliable. The second generation computers used magnetic core technology for primary memory. They used magnetic tapes and magnetic disks for secondary storage. The input was still through punched cards and the output using printouts. They used the concept of a stored program, where instructions were stored in the memory of computer.
•  Software Technology The instructions were written using the assembly language. Assembly language uses mnemonics like ADD for addition and SUB for subtraction for coding of the instructions. It is easier to write instructions in assembly language, as compared to writing instructions in machine language. High-level programming languages, such as early versions of COBOL and FORTRAN were also developed during this period. 
• Computing Characteristics The computation time was in microseconds. Physical Appearance Transistors are smaller in size compared to vacuum tubes, thus, the size of the computer was also reduced. 
• Application The cost of commercial production of these computers was very high, though less than the first generation computers. The transistors had to be assembled manually in second generation computers.
• Examples PDP-8, IBM 1401 and CDC 1604. 

Second generation computers generated a lot of heat but much less than the first generation computers. They required less maintenance than the first generation computers