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.