Source : Free On-Line Dictionary of Computing

second generation computer
     
         A computer built from {transistors}, designed
        between the mid-1950s and mid-1960s.
     
        {Ferrite core memory} and {magnetic drums} replaced {cathode
        ray tubes} and {delay-line storage} for main {memory}.  {Index
        registers} and {floating point} arithmetic hardware became
        widespread.  Machine-independent {high level programming
        languages} such as {ALGOL}, {COBOL} and {Fortran} were
        introduced to simplify programming.
     
        {I/O processors} were introduced to supervise input-output
        operations independently of the {CPU} thus freeing the CPU
        from time-consuming housekeeping functions.  The CPU would
        send the I/O processor an initial instruction to start
        operating and the I/O processor would then continue
        independently of the CPU.  When completed, or in the event of
        an error, the I/O processor sent an {interrupt} to the CPU.
     
        {Batch} processing became feasible with the improvement in I/O
        and storage technology in that a batch of jobs could be
        prepared in advance, stored on magnetic tape and processed on
        the computer in one continuous operation placing the results
        on another magnetic tape.  It became commonplace for
        auxiliary, small computers to be used to process the input and
        output tapes off-line thus leaving the main computer free to
        process user programs.  Computer manufacturers began to
        provide system software such as {compilers}, {subroutine}
        libraries and batch monitors.
     
        With the advent of second generation computers it became
        necessary to talk about computer systems, since the number of
        memory units, processors, I/O devices, and other system
        components could vary between different installations, even
        though the same basic computer was used.
     
        The instruction repertoire of the {IBM 7094} (a typical second
        generation machine) had over 200 instructions including data
        transfer instructions for transferring a {word} of information
        between the CPU and memory or between two CPU registers;
        fixed-point and floating point arithmetic instructions;
        {logic} instructions (AND, OR etc.); instructions for
        modifying {index registers}; conditional and unconditional
        branching; {subroutines}; input-output operations for
        transferring data between I/O devices and main memory.
     
        (1996-11-25)