741 AND 555 CHIPS     741 and 555 are two of most famous chips ever made. 
                      Both chips are over 25  years old and, 
                      although are newer, faster, models, still in production.
                      741 is an operational amplifier and was bed rock of 
                      analogue signal processing over decade. T555 is  timer 
                      that so versatile it defies definition..
microA741             741 started life at Fairchild as microA741 in  1967.
                      designed by Dave Fullagar who emigrated from England in  
                      1965 after two years for Ferranti in Edinburgh.
                      Marketing's original idea to make version of microA709 
                      but with every parameter improved by a factor of two.
                      I had idea for another design. 709  suffered from latch-up, 
                      was difficult to  stabilise and had  other quirks. 
                      idea was for  something much simpler to use, idea became the 741. 
                      The 'improved 709' was passed on  to someone else,  
                      and eventually emerged as the microA725.
                      The 741 is a two stage internally compensated design. 
                      Bob Widlar first  to design a two stage op-amp (LM101) 
                      Thought of internal compensation to avoid instability in 709. 
                      Other new  feature was the input stage. 
                      difficulties of this section had  been addressed in LM101, 
                      but Widlar's solution didn't seem quite right to  me. 
                      Was playing on my mind when suddenly, 
                      on  way to a skiing trip, solution came into my mind." 
                      He started work on the microA741 in 1966 and 
                      it was announced in May the following year.
                      Fullagar didn't stay at Fairchild for long:
                     "Shortly after the uA741 was  announced, 
                      I left Fairchild to join Intersil, 
                      where designed majority of early analog products. 
                      Most popular of these was the ICL80079 a 
                      monolithic FET input op-amp."
                      Although the 741 is Fullagar's most famous design, 
                      the one he best remembers  was for a Canon: 
                      "My favourite product was a camera  circuit developed for 
                      Canon  Camera in Japan. It took the log of three inputs 
                      (aperture, film speed  and light intensity), summed the logs, 
                      took antilog and derived a shutter 
                      speed  output. The whole circuit was temperature 
                      compensated, and used a total 
                      of about ten transistors."                 
                      Fullagar co-founded Maxim 1983  as VP of Engineering, still there
                      although not directly connected with design work. 
                      "I'm  semi-retired now, at Maxim means a 40 hour week!"
                      
                      
                      
                      555 was designed few years later by Hans Camenzind w 
                      for Signetics (Now Philips).
                      Since  1970's both Fullagar and Camenzind work in  
                      electronics industry.
                      Camenzind started his own company, Interdesign, He sold 
                      Interdesign  to Ferranti in 1978 has operated as Array 
                      Design ever since. He 
                      said: "I design  primarily custom ICs 
                      complement of standard ICs for 
                      Zetex, Oldham, UK. The 555 was my tenth design 
                      I am now up to number 135."
                             
birth of the 555      Camenzind on the birth of the 555
                      1967, designing repeatable IC tuned circuits impossible.
                      interviewed by Signeticsproposed  they let me try to 
                      designed one using PLL .found PLL in 1935 Proceedings 
                      IRE  it wouldn't need on-chip repeatability since it 
                      can set itself in step with an external frequency.
                      with Alan Grebene (Exar.Micro Linear) aGraham Righby, 
                      to design the circuit blocks for PLLL. Righby came 
                      a clever voltage-controlled oscillator operate  high 
                      speed  and Grebene engineered it. the first IC PLL, the 
                      NE560. I quite like  outcome ,  I decided to find a 
                      better VCO on  my own.
                      used a voltage-to-current converter  current set external 
                      resistor.current charged discharged an external capacitor.
                      Control of current direction came from two comparators.  
                      Both current source and  comparator thresholds 
                      were dependent on  supply voltage, but two 
                      effects  compensated, makingfrequency supply-independent.
                      Using this principle Jack Mattis   565 PLL and  566 
                      waveform generator both of which are available, w
                      1970 I 4-month break to write book. Instead of returning
                      asked for a 1-year contract as a consultant to use   
                      VCO principles to design a timer, 
                      circuit which could oscillate or run for  
                      just one cycle.
                      Signetics' engineering didn't think much of idea, but 
                      Art Fury, marketing man, did had  gut feel it would 
                      sell and broke tradition of introd new IC at high price 
                      then letting the price drop.set price 555 at 75 cents  
                      from   start.
                      got contract,completed circuit-design portion 6months. I 
                      already written a report on design when realised that I  
                      incredibly stupid.had assumed compensation principle only 
                      work with linear voltage-to-current converter 
                      would fall apart if  RC time constant was used. 
                      I decided to check out and found assumption not true a
                      RC time  constant worked same way. simplified design   
                      reduced number of pins from 14 to 8. Ironically an 
                      employee at Signetics quit his job shortly 
                      after I delivered the report and took the design to a  
                      start-up company. They beat Signetics to the market - 
                      with the wrong design.  lasted exactly three months."
                      Other versions of  555 been seen since  original. 
                      Camenzind said: 
                      "In 25 years there has never been an improvement
                      on the venerable old 555,  apart  from a CMOS version 
                      by Dave Bingham at Intersil. I have just finished  
                      redesigning the circuit from ground up. 
                      The new version is much improved. It  
                      works down to 1 Volt, retains the speed, 
                      has better accuracy, but only draws  
                      one-tenth the current." And added wryly: "Experience  
                      helps, but so do smaller  
                      device geometries and computer-aided design!"
father analog design  both Fullagar  Camenzind named designs by Bob Widlar.
                      Camenzind said: "impressed me the most over the years is 
                      the National LM10, by Bob Widlar. chiplike a symphony, 
                      all  components playing in perfect harmony.
                      it took Widlar five years to design it."
                      Fullagar said: "I always had a lot of respect 
                      for Bob Widlar's designs; he  
                      really was the 'father' of analog design. 
                      His bandgap reference (Solid State  
                      Circuits Conference. Feb.1979) was very elegant, 
                      why didn't I think of it?"
                      The bandgap reference also got Widlar to the top 
                      of the list of the 10 most  
                      influential analogue designs, voted on at this 
                      year's ISSCC conference. The 
                      top  five were: 1. Bandgap reference/ regulator, 
                      2. Differential pair, 3. 
                      Translinear circuits 4. Current mirror/source 
                      5. Switch capacitor circuits.
                       The op-amp as we know it was also a Widlar idea. 
                      Fullagar said: "In the very  
                      early days Widlar did some designs of his own back, 
                      then presented them to the  
                      industry. One of these was the 'differential in, 
                      single-ended out' op-amp. 
                      This  was at the time when some were thinking 
                      of differential outputs on 
                      operational  amplifiers.
                      Widlar was also first with the three terminal 
                      voltage regulator, the two 
                      stage  op-amp and has been credited with 
                      the invention of the current mirror. 
                      ELECTRONICS 
                      ELECTRONICS WEEKLY 13/11/96 P18                                              
IBM choose  8088      rather than  68000 as processor for their first PC?
                      IBM PC supposed to be low-end model machine 
                      compete with CP/M machines and Apple II, 
                      needed a 16-bit CPU, but not too much memory.
                      With 8-bit data bus, 8088 cheaper hardware 
                      limited address space (1MB, reduced by IBM's to 640 KB) 
                      wasn't  perceived as a problem 
                      8088 allowing easy proting of 8080/Z80 code.
                      lots of software could be produced very by porting
                      existing CP/M programs  Microsoft Basic and WordStar
Bill Gates            Microsoft bought MS-DOS from a Seattle company, 
                      and it was called QDOS then 
                      (Quick and Dirty  Operating System). 
VAX mean?             Why did early VAXen have model numbers starting
                      with "11",like 11/780, 11/750, and so on?
                      Rumour has it that 11/780 was 
                      originally intended as PDP 11/78 with
                      "Virtual Address eXtension" (i.e. virtual memory), 
                      but Digital choose to present their new 32-bit line of 
                      computers under the name "VAX" rather than"PDP".
                      The 11/xxx series of VAX machines 
                      all had a special "compatibility mode" in
                      which they can run PDP-11 code.
Why MS-DOS use '\'    as path separator, while Unix uses '/'?
                      Version 1 MS-DOS didn't have subdirectories or paths, 
                      The '/' character used  to denote command options
                      like '-' in Unix; common in CP/M, and DEC systems. 
                      version 2.0 of MS-DOS,  including subdirectories. 
                      Since '/' was used for command options
                      by many programs, character couldn't be used in paths. 
                      Microsoft thought '\' was  second best alternative. 
                      It's interesting to
                      say that is the shell who requires '\' as the 
                      path separator; the real DOS
                      is quite happy with '/', and when you 
                      program in C (for exemple), you can
                      write a path as "c:\\foo\\bar\\..." 
                      or "c:/foo/bar/...", and both work.
                      Also, there was an undocumented feature 
                      of DOS which allowed the user to
                      change the switch char, and freed '/' to 
                      be used as a path separator in the
                      command line. This no longer exists in 
                      DOS 5.0, and probably is absent in
                      DOS 6.0, as well (I couldn't test this).
Origins C ?           In 1963 at England's Cambridge University 
                      and University of London, 
                      researchers developed a ``practical'' version of ALGOL 
                      called it Combined Programming Language (CPL).
                      1967 at Cambridge University, 
                      Martin Richards invented a simpler,
                      stripped-down version of CPL 
                      called it  Basic CPL (BCPL).
                      1970 at Bell Labs, Ken Thompson developed  even
                      more stripped-down and simpler; 
                      since it  included just the most critical part of BCPL,
                      he called it B.
                      Ken  had stripped down language _too_ much.
                      1972, his  colleague Dennis Ritchie added
                      a few commands to B, to form a more extensive language. 
                      Since thatlanguage came after B, it was called C. So 
                      C is a souped-up version of B, which is a stripped-down 
                      version of BCPL, which is a stripped-down version of CPL,
                      which is a  ``practical'' version of   ALGOL.