 The so-called second-generation computers can be taken to be those produced during the second decade of the electronic computer era (approximately )

 They used high-level languages such as FORTRAN (1956), ALGOL (1960) & COBOL ( ). I/O processor was included to control I/O operations.  Around 1955 a device called Transistor replaced the bulky Vacuum tubes in the first generation computer. Transistors are smaller than Vacuum tubes and have higher operating speed. They have no filament and require no heating. Manufacturing cost was also very low. Thus the size of the computer got reduced considerably.

 It is in the second generation that the concept of Central Processing Unit (CPU), memory, programming language and input and output units were developed. The programming languages such as COBOL, FORTRAN were developed during this period.

 1. IBM 1620 : Its size was smaller as compared to First Generation computers and mostly used for scientific purpose.

 Transistors were used instead of Vacuum Tube.  Processing speed is faster than First Generation Computers (Micro Second)  Smaller in Size (51 square feet)  The input and output devices were faster.  Example: IBM 1400 and 7000 Series, Control Data 3600 etc.

 Many of the improvements associated with second- generation computers actually first appeared in vacuum tube or hybrid machines. The IBM 704 vacuum tube had index registers and floating-point which was rudimentary operating system. The later models of 704, 709, had input out-put processors(then called "data synchronizers " and later "channels" )which were special-purpose processors used exclusively to control actions were controlled directly by the CPU; this is now termed programmed IO. With the second generation it became necessary to talk about computer systems, since the number of memory units processors, IO devices, and other system component could vary between different installation, even though the same basic computer was used.

 The IBM 7094 Model I was amide number of IBM's second generation of scientific computer. Built with discrete transistors. The shows the console. The 7094 system is about the same size as 709 and has the same kind of principle. The IBM 2302 disk drive for the The disk platters are 24 inches in diameter and the head assembly is positioned with compressed air. It is one of the last model this size and can store 300 MB.

 Smaller in size as compared to the first generation computers.  The 2nd generation Computers were more reliable  Used less energy and were not heated.  Wider commercial use  Better portability as compared to the first generation computers.  Better speed and could calculate data in microseconds  Used faster peripherals like tape drives, magnetic disks, printer etc.  Used Assembly language instead of Machine language.  Accuracy improved.

 Cooling system was required  Constant maintenance was required  Commercial production was difficult  Only used for specific purposes  Costly and not versatile  Puch cards were used for input.