Strolling Down the Memory Lane
If I look back about 42 years in my life, I can bring back those days when we were simulating the trajectories of the missiles. The work was carried out Defence Research and Development Laboratory (DRDL) situated in Hyderabad.
This was the birth place of Computer Society of India. As compared to the current scenario, we hardly had any computing resources with us. I joined the Computer Centre at DRDL in 1972. Before this, Col Balasubramaniam the then Head of Computer Centre went to Delhi on promotion. I missed the opportunity to work with him as my seniors used to fondly remember him.
We had at our disposal an IBM 1620 computer for all the computing needs of not only DRDL as well as other Laboratories like Defence Electronics Research Laboratory (DLRL) and Defence Metallurgical Research Laboratory (DMRL). I saw in the log of late 60s that we were also catering to prestigious institutions like Tata Institute of Fundamental Research (TIFR). It will be interesting to note that all of software relating to aerodynamics, structures, control and guidance systems, propulsion (solid and liquid) systems, simulation etc., was carried out in IBM 1620. This computer is a 8 bit system with memory of 40K. All the programs were written in FORTRAN II language. We needed a fullfledged Air-Conditioning system which was provided by Military Engineering Group (MEG).
The console of the computer had multiple lamps and buttons. Perhaps the computer operator in those days had a lot of work to do. With our experience we were able to decipher the operations that are currently executed. The input for this system was the source code in punched cards. The picture of the system is in Fig. 1 and the expanded picture of the console is in Fig. 2. One may wonder how the computer processing for the missile development was done in those days.
Having gained experience in scientific computing I joined National Remote Sensing Agency (NRSA) now called NRSC, in 1977.
In those days importing even a medium sized computer was a cumbersome process. During the initial days at NRSA we did not have general purpose computer at our disposal. So we were using the IRIS 55 System (French) at Electronics Corporation of India (ECIL), Hyderabad. This was a 16 bit system with 256 K memory. When we were sending our source cards to the console operator, the errors of compilation were printed in French and needed translation for the correction process. A typical IRIS 55 system is displayed in Fig. 3.
We were also booking time on IBM 370/155 at IIT Chennai. The booking slots are for a minimum of 1 hour and usually start at mid night. Normally our timings were between 2:00 AM and 4:00 AM. All the software programs for the satellite data processing of the LANDSAT Satellite of USA were done in this system during that time. The staff in the lodge where we stayed used to wonder as to what we were engaged in those unearthly hours. Our rooms were locked in the day as we were sleeping. A partial view of the system is in Fig. 4.
The computing facilities were added in our office were of PDP-11 families from Digital Equipment Corporation (DEC) which were the work horse for satellite data acquisition at Shadnagar Earth Station situated about 60Kms from Hyderabad as well as at Balanagar, Hyderabad. Whenever, a prospective customer wishes to evaluate PDP systems our vendor M/S Hinditron Computers used to bring them to our premises as we had the PDP family of systems with us.
Some of these systems are in the following figures.
This was followed by the acquisition of VAX Series of Computers of DEC. This was used when our first Indian Remote Sensing Satellite (IRS-1A) was launched in 1988. A typical view of VAX 11/730 is below.
Now you may imagine that any of the current day desktop with 2 GB RAM and 500 GB of Memory installed in homes is much more powerful than any of these systems but still good scientific work was carried out in those days.
About the Author
Dr. S Natarajan holds Ph. D. (Remote Sensing) from JNTU Hyderabad India. His experience spans 33 years in R&D and 10 years in Teaching. He worked in Defence Research and Development Laboratory (DRDL), Hyderabad for Five years and later worked for Twenty Eight years in National Remote Sensing Centre (NRSC) at Hyderabad, India. He was trained in Digital Image Processing in DLR, Germany and in Automated Cartography at IFAG, Germany during 1979 and 1980. His areas of interest are Soft Computing, Data Mining and Geographical Information System.