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Tuesday, October 03, 2006

My First Computer: Sinclair ZX81

My First Computer: Sinclair ZX81 Collecting, Computers, Science & Technology An article on the rapid developments in the computer hardware in the last twenty years. That had me thinking about the very first computer I ever owned. It was in 1981 that I bought my first “real” computer. At that time, being able to use a programmable calculator was a “cool” thing to do. I was one of the few lucky ones in my class (3rd year of civil engineering) to have and program a Logic P- 512 (programmable calculator with 512 step program capacity). One day, going through a second hand issue of “Popular Mechanics”, I came across an article about the new affordable and highly popular new computer for hobbiest, called the Sinclair ZX81. Even before finishing the article, I somehow knew that I had to have this toy. Next day, a close friend of mine and I went into the city center looking for that computer, and to our surprise, we found it in the bookstore. There were no computer shops at that time; so all calculators, typewriters, etc. were instead sold on bookshops, at least in my city.
Programming interested me so much that I pulled together all my savings and resources to buy a Rs 3,000 (nearly US$ 200 at that time) machine. Once I bought the computer and brought it to my hostel room in the university, and unpacked it with great expectations, I realized that I could not use it without a TV and a cassette player. The computer had no screen or backup storage of its own. That really damped my enthusiasm. I had no more savings to buy a TV and a cassette player. By that time, everyone in the hostel had heard about the new computer, the first of its kind in the entire university of over 4,000 students, and friends were flocking into my room to take a look. One of my friends brought in his TV a 12" black and white antique, and another friend offered his walkman, so we set it up and switched it on. Nothing happened, except we saw a blinking dot, the cursor on the blank screen. We had no software to run, so once again all excitement frizzled out. Once the crowd dispensed, un-impressed and disappointed, I began thumbing through the manual and got acquainted with the “Basic” Language. By the next morning I had successfully written my first computer program, which was the famous racket and ball game. It was actually nothing fancy, you moved a small straight line at the bottom of the screen (the racket) by using ‘L’ x ‘R’ keys trying to deflect a ball (the cursor) moving at a turtle speed. This was, however, exciting enough for me and most of my friends who spent hours playing, so finally we had something to show for the computer. I then went on to write a full frame analysis program using matrix method as my 4th year project on the same computer, within the limits of its ‘8K’ memory. Yes, not 8Mb, but just 8Kb.
While I was planning to write this article, I thought where would I get the specifications and a picture of the computer I used nearly 23 years ago. So I turned to Internet and entered ZX81 in Google search. To my surprise there were over 20,000 pages containing information about this computer. I later found out that ZX81 has become a collectors’ item and there are several websites and groups entirely dedicated to this marvel of computing.
===================================Dr. Naveed Anwar is Associate Director of ACECOMS, AIT. ACECOMS is provide an impetus to the research in civil & structural engineering computations and to the development of quality computer software tools for engineering applications, their wide spread promotion, seminar and training on their effective use. Please visit at


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