Racing the Clock: My First Big Computing Challenge on the IBM 360

Thurston Road (today - Kumaranathunge Munidasa Mawatha), University of Colombo, late 1970s — the place where my thesis journey began. (Photo Archive Library (c) Turrance Nandasara)

From the Colombo Campus to the Department of Census and Statistics, each location marked a step in a race against time.

It was the late 1970s, and computing in Sri Lanka was still in its infancy. Mainframes were rare, expensive, and intimidating machines—giants that lived in air‑conditioned rooms, guarded by operators in white coats. As a final‑year student, I never imagined I’d get to work on one. But fate—and an ambitious thesis—changed that.

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“The survey involved 2,000 houses, hundreds of variables, and thousands of data points — far beyond the reach of any calculator.”

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My project carried a long, serious title: Multiple Regression Analysis for a Survey on Housing Conditions in Sri Lanka. It was supervised by Dr. Seneviratne and guided by Prof. V. K. Samaranayake. The survey itself was massive: every detail of each house was recorded — from roof and wall materials to household size, income sources, and even the surrounding environment.

IBM System/360 Model 25 — similar to the machine installed at the Department of Census and Statistics in the 1970s, that transformed my thesis from a calculator exercise into a computing project — and my career along with it.

Did You Know? — Computing in Sri Lanka, Late 1970s

• IBM 360 Arrival – The IBM System/360 series was introduced globally in 1964, but Sri Lanka’s first units arrived much later. One was installed at the Department of Census and Statistics, and later, in other government departments.

• Air‑Conditioned Sanctuaries – Mainframes required strict climate control; even a small temperature rise could cause system failures.

• Punch Card Culture – Each card held exactly 80 characters. Dropping a deck could mean hours of painstaking re‑sorting — or starting over from scratch.

• Limited Access – Machine time was precious. At the University of Colombo, students could submit punched cards for compilation free of charge, but had no direct access to operate the computer. Special arrangements — often at odd hours — were needed for hands‑on use.

• The Human Factor – Operators, programmers, and supervisors formed close‑knit communities. Mentorship, collaboration, and trust were as important as the hardware itself.

The Access Problem

The Department of Census and Statistics housed an IBM 360 Model 30 — among the most powerful machines in Sri Lanka at the time. But there was a catch: students could only use it for learning purposes by submitting their FORTRAN IV code as a deck of punched cards for compilation.

Any other work was charged at commercial rates — about Rs. 750 per hour, roughly a month’s salary for an Assistant Lecturer.

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“Rs. 750 an hour — more than I could dream of paying, and impossible to estimate how many hours I’d need.”

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When I explained my situation to Prof. V. K. Samaranayake, he devised a brilliant workaround: the Department of Mathematics would take on my project as a consultancy assignment, funded from its own consultancy budget. My supervisor, Dr. Kevin Seneviratne, took full responsibility for making it happen.

It was an extraordinary gesture of support — one that found its way into the 1979 Annual Report of the Statical Unit of the Department of Mathematics and remains etched in my memory as a turning point.

Each card is a single line of FORTRAN IV — precision, patience, and the constant fear of dropping the deck. Programming was as much a physical craft as an intellectual one.

Punch Cards and Patience

With access secured, the real work began. In those days, programming meant first writing your code on paper, then punching it into stiff rectangular cards using an IBM Model 029 Card Punch Machine available at the Department of Mathematics. My program, written in FORTRAN IV, eventually grew to about 1,500 lines — spread across more than 5,000 cards, including the dataset.

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“No one got a large program right the first time — debugging meant re‑punching cards again and again.”

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The process was slow and unforgiving. You would send your carefully ordered stack of cards to the mainframe centre at the Department of Census and Statistics, wait for the compilation, and then receive a thick bundle of continuous‑form paper with your program listing and error messages. Sometimes, the error reports alone ran to more than 200 pages.

Prof. V. K. Samaranayake and Dr. Kevin Seneviratne — mentors whose support opened the mainframe’s doors and made the improbable possible. (Photo Archive Library (c) Turrance Nandasara)

Two Months of Work… and a Friday Surprise

The process of computing dragged on for more than two months. Finally, on the very last working day before my thesis deadline, I got the complete results. It was a Friday. The thesis had to be submitted by 4:00 p.m. on Monday — or it would be rejected outright.

“Two days to analyse, write, chart, type, bind — and deliver. Alone, it was impossible.”

Kurunegala — where my thesis was bound in hard cover before the final dash to Colombo. A quiet provincial town that became the last checkpoint in a two‑month sprint.

Calling in Reinforcements

I called a school friend who had just started his first job as a bank manager. Without hesitation, he stepped in to help. He arranged a typist, an artist to draw charts, and a vacant room at the bank to serve as our “thesis war room.” We worked through the weekend, fuelled by urgency and determination.

The Final Dash

By Monday morning, the thesis was complete. I travelled to Kurunegala to have it bound, then caught the bus to Colombo — 120 kilometres away. The journey took three and a half hours. I arrived just in time to hand it over to the University administration, minutes before the deadline.

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“Minutes to spare — and two months of work finally in the hands of the examiners.”

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From IBM System 360/Model 25 to mentors — the legacy of a project that bridged disciplines, decades, and the gap between opportunity and determination. (Photo Archive Library (c) Turrance Nandasara)

Looking Back

That project was more than just an academic requirement — it was my initiation into the world of computing. The IBM 360, the punch cards, the endless debugging, the last‑minute race to the finish line — all of it taught me lessons I’ve carried throughout my career: persistence, creative problem‑solving, and the power of teamwork.

In an era when computing power was scarce and expensive, it wasn’t just the machine that mattered — it was the people who believed in you, and the determination to see the job through.