second generation computer
<architecture> 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)
Nearby terms:
secondary damage « secondary key « secondary storage
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second generation computer » second generation
language » second level cache » second normal form
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