Exactly 43 years ago, on April 7, 1964 the entire concept of computers has changed, when Big Blue announced its baby – IBM System/360 (S/360).
According to wiki The design is considered by many to be one of the most successful computers in history, influencing computer design for years to come. (The 360 and its successors are unquestionably the most profitable line of computer systems in history).
image is taken from ibm
Today, S/360 would seem like a total archaism – with several CPUs, it performed less than a MIPS or a 1,000,000 Instructions (operations) Per Second, having only 24KB of RAM (the cheapest model).
But the real “secret weapon” of S/360 was not at all its speed, but its ability to multitask, where many tasks could run concurrently. This was a huge step forward which doubled, or in some cases, tripled the overall system performance. Instead of sequential time distribution among users who stayed in line to get a machine’s time portion, S/360 could serve them simultaneously. Today we would say that S/360 was a server, and users were clients (terminals).
Another important innovation to computer industry that came with S/360 was a clear separation of hardware and operating system (OS/360). First time in computer history Operating System was introduced as a separate and independent component. Today mainframes use VMs (virtual machines) which are used to run many operating systems simultaneously on a single box. It’s worth to mention that Linux (zLinux what it is called on mainframes) is one of such OSs. More on zLinux here.
System/360 was an extremely risky project for IBM. Company invested $5 billion dollars (which made this project the most expensive computer/system project in history), and hired 60,000 people. However, this risk was justified in 5 years, when IBM’s revenue doubled.
According to IBM, today mainframes hold 65% of all the data accumulated by humanity in computer based format. Which is an interesting fact. Another amusing fact is that IBM zSeries (modern mainframes) sales grew 10.3 percent in 2006. ;)