Laptop computers and 60 years ago cost hundreds of millions of dollars of IBM mainframe performance PK

In the 1960s, many universities purchased IBM 7090 mainframes. 7090 was the first all-transistor computer series, a ceiling-level smart device at the time, so the cost would have been $20 million, which, discounted by purchasing power, $20 million in the 1960s is equivalent to about $180 million today.

The 7090 had a clock cycle of 2.18 microseconds, so it operated at slightly less than 500 KHz. but in those days, instructions were not pipelined, so most instructions took more than one cycle to execute. Some integer operations required 14 cycles, while a floating-point operation might take 15 cycles.

As a result, the 7090 is usually estimated to execute about 100,000 instructions per second. Most modern computer cores can run at a sustained rate of 3 billion instructions per second, with a much faster peak speed. That’s 30,000 times faster, so a modern chip with four or eight cores can easily reach 100,000 times faster.

Today, your laptop has 16 gigabytes of main memory. the 7090 has a maximum capacity of 144 Kb. to run the same program, you need to move a lot of data in and out of the 7090, and you have to use tape. The best tape drives of the time had a maximum data transfer rate of 60KB per second. while 12 tape units could be connected to a single 7090 computer, this rate needed to be shared between them. However, this sharing required a group of human operators to swap tapes on the drive, and reading (or writing) 16GB of data in this manner would take three days. As a result, data transfers are also about 100,000 times slower compared to today’s speeds.

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