A12- A REVOLUTION IN COMPUTING STARTING FROM ERA OF MINI COMPUTERS

By pragyansharma polavarapu

INTRODUCTION

(1) The MINI computers not only brought down the size of computer (to size of a table top radio) but various new technologies were also introduced making the computer all powerful. The length of “computer word”(the “bytes” conmprising a string of 0s and 1s ) was standardized to 8/16/32 bit size by the IEEE. Many sophisticated computer languages BASIC/FORTRAN/COBOL etc with a mathematical base were invented. Use of computer naturally extended to many fields .

(2) Mini in the client-server environment was useful for bank counter supervision ,college teaching with live question-answer sessions between the professor and student ,ticket booking counters , government work etc. Client server technology had another big use in industries especially industries dealing with hazardous chemicals or industries where live watching minute by minute was necessary. Network of computer nodes containing sensors were established in hazardous spots in industries where humans cannot safely enter . Signals are sent from the sensors to a central server computer monitored by a senior experienced engineer. The engineer could initiate immediate necessary action to manage a difficult situation.

(3) “Distributed Computing” was another innovation . It facilitated easy work distribution with senior professional people in charge of each section ---as in a big bank, big government office, a big university etc . The vast data belonging to each department was loaded into a powerful central computer of that section instead of keeping all data in a single central computer . The central computer and server computers of any section could be connected when necessary to share data. Such “distributed computing” became possible when software for networking of computers was standardized.

DEVELOPMENT OF PRINTED CIRCUIT TECHNOLOGY

We see tiny circuit boards in modern desktop computers,laptops and other digital equipment. They are colored circuit boards of metal and of small dimensions of two or three inches or similar small size. On these PCBs a few tiny rice grain sized electronic parts are rigidly fixed . Such parts are fixed on top layer by soldering. There are raised metal paths on the top layer of PCBand they act as connecting lines for “integrated circuits”

When we give a computer for maintenance we see one or two such tiny circuit boards inside the computer . These printed circuit boards are well known in engineering world as PCBs. They connect the most important “integrated circuits” which contain not a few dozen but a few hundreds of thousands transistor triodes which create the complicated logic circuits of computers.

When a PCB is damaged it is simply discarded because nobody can repair any individual transistor in the hundreds of thousands of them contained in the integrated circuits printed on the PCBs.

When the damaged PCB is replaced by another correct PCB the computer starts working like a new computer. Some of the world’s greatest electronics technology is contained in such PCBs. Their internal architecture is as complicated as that of a semiconductor chip.

Modern PCBs--though they look like thin plates—are complicated works of engineering --with peculiar circuit diagrams , hair thin metal lines, tiny round conducting metal –lined holes . Modern PCBs contain “integrated circuits” which contain thousands of logic circuits made of hundreds of thousands or in some cases even millions of submicroscopic transitors.

The hundreds of thousands or millions of transistors are contained only in the integrated circuit silicon wafers embedded in the PCB. Integrated circuits are constructed on doped silicon wafers of extreme thinness which can conduct electrons in a limited way . in side such doped silicon wafers millions of transistors of near molecular size are created by sophisticated computer programming ,chemical and thermal processes and photo-etching processes.

Another most important thing is that modern PCBs are multi-layered. Several very thin layers with alternating conducting and non conducting layers exist in PCB. The conducting layers in the PCBs may be very thin metal sheets.on these conducting layers are embedded the the extremely thin silicon wafers containing integrated circuits . millions of transistors grouped into logic circuits are etched on these silicon wafers.These are called “ integrated circuits”

millions of transistors contained in integrated circuits normally require a very vast surface area on the PCB . construction of PCB in the form of several equal sized layers of alternating conducting and non-conducting layers stacked one above another takes far smaller space. All the conducting layers of PCBs are interconnected by hair thin metal lines and vertical conduting metal-lined vertical holes .

These complex PCBs are engineering wonders and are mass produced with extreme precision using special computer programs and conform to highest standards set by international agencies. pcbs have great importance in computers, tvs ,cell phones , digital cameras,computer mouse etc . suffice it to say that PCB manufacturing has developed as a 60 to 80 billion dollar industry.

When damaged, such PCBs are discarded because damaged circuits among millions of sub microscopic transistors can not be repaired. PCBs became popular only in early years of MINI computers from 1950s.Pcbs also reduce size and weight of electronic equipment .PCBs revolutionized space exploration because space craft could be made lighter.