2 nd Generation Computers 1995 1964 The socalled

2 nd Generation Computers 1995 -1964

� The so-called second-generation computers can be taken to be those produced during the second decade of the electronic computer era (approximately 1955 -1964)

The second-generation computer used transistors for CPU components & ferrite cores for main memory & magnetic disks for secondary memory.

The scientists at Bell laboratories developed transistor in 1947. These scientists include John Bardeen, Walter Brattain and William Shockley.

� They used high-level languages such as FORTRAN (1956), ALGOL (1960) & COBOL (1960 - 1961). 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.

Some of the computers of the Second Generation were � 1. IBM 1620: Its size was smaller as compared to First Generation computers and mostly used for scientific purpose.

2. IBM 1401: Its size was small to medium and used for business applications.

3. CDC 3600: Its size was large and is used for scientific purposes.

Features � 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.

The earliest transistor computer appears to have been an experimental machine, the TX-O , which was operational in 1953.

� Many of the improvements associated with secondgeneration 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.

IBM 7094 � 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 7094. 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.

IBM 2302 Disk Drive

Advantages of Second Gen. Computers � � � � � Smaller in size as compared to the first generation computers. The 2 nd 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.

Disadvantages of Second Gen. Computers � 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.