A15- RESEARCH IN THE PERIOD OF MINIS AND LATER.

 BY  Pragyansharma  Polavarapu

THE  RESEARCH  FINALLY RESULTED IN CREATION OF THE MOST BEAUTIFUL “MICROS” (DESKTOP/LAPTOP/DIGITAL PHONE )

1) Metals(both elements and alloyed metals) are best conductors of the electric current. When metal objects are put in current circuits there is a flow of billions of electrons in a systematic way from negative electrode to positive electrode through the wire circuit. This is because the electrons in outermost orbits in the atoms jump out and form a stream towards positive pole. But some of the electrons from the billions in the stream jump back into outer orbits every moment and keep the atoms perfectly neutral. The stream of electrons moves at violent speed . The electric impulse travels at unbelievable speed of nearly 300,000 kilometers per second!

(2)Nonmetals ( like carbon, sulphur, silicon etc ) , organic and compound substance like glass, stone, wood, plastic  etc do not  conduct electricity.   In them also there are  billions of elecgtrons  but they are very tightly bound in the orbits and not a single electron can come out. There are no free electrons in them to create an electric current.

 (3) However among non-metallic elements  there are some substances called “semiconductors”-- like Germanium and Silicon.  At ordinary temperatures when put in a current circuit they do not conduct electricity just like any other non-conductor .  But when a piece of the  semiconductor ( kept in the electric circuit) is strongly heated it starts conducting electricity! This is indicated by the fact that an electric bulb kept in the same circuit starts to glow and give light!

(4)  Far more important characteristic and  property  which created  entire engineering technologies leading to creation of modern small computers like desktop and laptop and the digital phone is the following.    Semiconductors in crystalline form have a systematic geometrical arrangement  of atoms called chrystal lattice.  The atoms  are arranged in a three dimensional grid at the corner points and held rigidly by the electron bonds. In normal Silicon all the places in the crystal lattice are filled  only with atoms of Silicon and it is a non-conducting material.

(4) Scientists deliberately introduced into the crystal lattice of Silicon (and also other semiconductor elements  like Germanium)  a few atoms of  another selected element like Boron and Phosphorous.  The atoms of other chemical element occupy some corners of crystal lattice in place of Silicon    as  “impurities”. The impurities are injected into the crystal lattice of the semiconductor —through advanced  chemical processes,thermal  and other  processes. The electron balance in the semiconductor substance is disturbed by such doping of “impurities”. In some  semiconductors (p-type)   a  shortage of electrons arises and in some  semiconductors( n-type) there is an   excess of electrons. This excess /shortage of electrons make the semiconductor electrically conducting.

TRANSISTOR TRIODES

(1) The above discovery led to creating  transistor triodes  by joining N-type and P-type doped semiconductors with a third very thin silican wafer plate in between. In the huge sized computer-calculators of 1940s using thermionic valves,  the triodes were  created by modifying the diodes creating an extra electrode inside with a positive wire grid . Those triodes also  performed as  high speed switches switching current on/off millions of times each second! This power of triodes in high speed switching of currents gives the computer the power of solving  toughest  mathematical and logic problems in fraction of second.

(2)The tiny transistor Triodes also perform all functions as done by the large the thermionic triodes  and also more efficiently. In modern computers hundreds of thousands of transistor triodes  are used to create all the logic and mathematical parts of computer. When the first transistors were a little bigger (of millimeter dimentions) small table top computers called MINIs were created during the period 1950s to 1970s using transistor triodes.(A single  old computer-calculator of 1940s would occupy  a whole hall)

(3)  The wonder is that the logic circuits in  MINIs created with  millimeter dimension transistors performed equally or even better than the giant size logic circuits created with 15000 thermionic electric bulbs in the computer-calculators  of 1940s. After developing the MINIs ,almost immediately, the  new  computer industry started to develop and prospered  during 1950s and 1960s. The computer most unbelievably shrunk  to the size of a table radio with  a key board and a  box of electrical circuit plates containing thousands of transistors and of size of a small refrigerator.  A small room and a chair and table were enough for the research engineer. The small computer called MINI  opened a great world of possibilities, uses and applications for the table top computer. The real era of computer had begun. This period of feverish research started in those  three decades and continues to this day! 

NEW TECHNOLOGIES  DURING AND AFTER THE ERA OF MINIs

(1) Slowly ,one after another, new technologies were developed utilizing the MINIs as the base. The MINIs  were manageable and of size of a table radio. Great technologies like WORD PROCESSING, OPERATING SYSTEMS, WINDOWS TECHNOLOGY , CLIENT –SERVER TECHNOLOGY, DISTRIBUTED COMPUTING were developed  one after another and computer manufacture and software and hardware industries developed into billion dollar industries.   All types of data ---textual , photo, music , speech, video data--- was processed at millionth-of-second speeds after  digitalizing all data . Most powerful networking technologies were developed converting the analogue sound to digital signals. Database technology was developed  to help banking type and statistical type work. The old (pre-computer age)technologies of wireless, cinematography, photography, sound recording were all superimposed into the digital computer technology. The computer became a most powerful tool by the end of 20^th century itself. Computer started dominating every field of human activity. The computer  became small  in size and most sophisticated and found a thousand uses and applications in every field of life from police crime detection work to cartoon films and digital music and digital cinema.

 (2)  Most important mathematical and logic circuits are  are activated by typing certain short English code words called  RESERVED WORDS. Various software languages like FORTRAN, BASIC ,COBOL were developed to process data using the  RESERVED WORDS ( which are separate for each software language) . Software languages are loaded  in advance  in the MINI  computer.

(3)A software program is created for solving a large group of similar problems. Problem data and formulas  are given to computer in the shape of the  software program in a strict serial order of steps. Software program is like the group of working steps written for solving an algebra problem. The software program is first loaded on the “MAIN MEMORY” board  of computer after instant translation  of English code into  01010101 code. The translation software exists inside computer. When a command is given the powerful processors-- CPU(central processor having overall control on all computer logic circuits)  and ALU( the centralized mathematical processor doing all mathematical work in fraction of a second)--  process data as per  formulas/instructions given by human engineer through the software program typed into computer. The SOFTWARE INSTRUCTIOby CPU and ALU step by step and provide reply in fraction of second. From internet we clearly learn that that modern desktops and laptops ar million times faster than the respected ENIAC.

(4) The ENIAC is always respected because it only  created--(back in 1940s using only the giant thermionic valve computers) --the concept of modern computing machine utilizing the speed of flow of electric current  to do mathematics at the speed of flow of electricity.

(5) Let us understand the difference in performance of old and new software languages. The old software languages like BASIC and COBOL construct software programs resembling  only strong single room houses . The  modern soft ware languages like C  and JAVA can construct  programs resembling strong multistoried houses with detailed room by room floor by floor structural plan. Languages like C ⁺⁺,JAVA ⁺⁺ are still more stronger. They are like expert engineers using new machinery and new techniques  to construct still bigger houses.

(6)The age of MINIs and a few later decades were a period of great research at universities and engineering institutions of the West and other developed countries in to the potentialities of the new intelligent machine called computer. The fruits of their research as described above truly brought a modern era in life of human society.

SILICON WAFER TECHNOLOGY

(1) Most importantly ,the silicon wafer technology dominated computer industry in many ways.  The technology of creating hundreds of transistors in the  same doped silicon wafer  ( MOSFET  technology)was perfected. The process of creating hundreds of thousands of transistors (and later millions of transistors in logic circuit pattererns in a small postage stamp size silicon chip ),creating limitless flash memory units in same wafer ---all such technology were perfected . These are all MOSFET  type technologies. The progress in technology ---integration of different types of submicroscopic electrical parts like transistors,resistors, capacitors,diodes etc in the same tiny silicon chip ---passed through several stages.  They were (a)small scale integration(SSI),(b)large scale integration(LSI) and ( c )very large scale integration(VLSI).

(2)A huge sized   cylindrical  Silicon crystal  ingot of 15 to 30 cms diameter and one or two meters length  is crystallized from  melted  sand (SI O ₂  ) under careful physical/chemical reaction conditions  .  Selected impurities(small quantities of boron/phosphorous as impurities) are added during the melting/crystallization process. The chrystalized ingot is   cut into  extremely thin wafers. The wafers are polished to a very great extent to a perfectly plane condidtion .Then in the doped wafers millions of transistors/resistors/ diodes/capacitors etc  are created by most sophisticated computer- controlled thermal /photo-lithographic processes. The circuits are connected  into several logic circuits in a repetitive way.

The wafers are  then cut into small chips and these chips of extremely thin wafers and containing several complicated electric logic circuits  were pasted electronically on to tiny high-technology PCBs ( printed circuit boards) and became the heart (CPU and CONTROL UNITs ). Into the many-layered PCBs,  the IC  wafers are overlaid and then   framed in metal jackets with current leads and could be directly fitted into computers.  It is a most wonderful high precision technology.

(3)The great thing is that such changes are effected almost at molecular level—nanometer level. Such deliberate introduction of “impurities”(i.e.new chemical atoms )inside the crystal lattice is called doping. Once the  semiconductor is doped there is no need of heating to make the  semiconductor  to conduct electric currents . Doped semiconductors  are used  in creating  diodes and triodes tens of thousands of times smaller than a millimeter. Some are created even in nano- meter dimensions . Roughly from second half of 20^th century, the technology of creating  millimeter size and even far smaller size transistor based circuits  developed . this led to establishment of large industries of radio/TV  and commercial electronics .

(4) Now let us learn about the tiny high-tech circuit boards PCBs which  find  inside every desktop/laptop computer.  In electronics industry, small circuit boards to rigidly fix electronic components  in  the circuits, are necessary in millions. The industry rose to the occasion and created small printed circuit boards (PCBs) using high technology , perfect accuracy and meeting highest industrial standards. At present manufacture of PCBs is said to be a 80 billion dollar industry. Now high precision  multilevel circuit boards are manufactured with printed metal line conducting paths on non-conducting Bakelite type material. Small few centimeters long multi-level circuit boards have  alternating conducting and non-conducting layers ,hair thin conducting printed metal lines, vertical conducting routes through metal lined holes etc .

(5) These are roughly the stages passed by computer industry to create the small table top computers and laptop computers we use nowadays   in thousands and hundreds of thousands . Technical name of these computers is  MICRO.   Using MOSFET  technology, millions of transistors in a shirt button sized silicon chip are created . These silicon chips are the heart of modern  Micro computer and the digital phone.

(6)The same technology applies to (a)the laptops which is of a single piece,foldable and can be carried to any place in a backpack bag.(b)tablets and I-Pads the thin and still smaller computers (c)digital phones ,the cell phones , which are really most powerful  network computers  of size of cigarette cases but possess  colossal data processing speed.

CONCLUSION

 (1)Finally an  important point is to be noted. Electronic gadgets including radio/tv/computer have inside them  transistor circuits containing hundreds of thousands or even millions of tiny transistors of submicroscopic size . Most important to note is the fact that such transistor circuits perform only at  very low voltages like 5volts, 10 volts or even less. With higher voltages they do not perform and break down.

(2) In radio or television,after  we hear/see a program the program  simply “evaporates into thin air”and disappears without trace like water flowing out of an open pipe . But in computer  a  program (text file, picture file,sound file,video file ) after they are read/seen/heard by us are  stored not just for hours and days but even years.they are stored in computer’s files and do not  disappear until we erase them .

(3)In a computer there is also danger of files disappearing/getting erased  suddenly  because of current fluctuations or when we give  wrong software commands etc. This is because the files are of magnetic/electronic nature and are affected by current fluctuations. As such ,soon after  we create an important file (text/photo/audio/video) we must save it by pressing the save button . Then  only it becomes a permanent file in computer .