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IT HISTORY
Six Retired Computers That Helped Shape Modern Computing
From paged memory to vector pipelines — the engineering problems behind six machines
Virtual address spaces, compatible instruction sets, parallel execution, and hardware protection are foundations of many computer systems today. None appeared out of nowhere with the modern microprocessor.
In the 1960s and 1970s, computer hardware took many different forms. Engineers working on mainframes and early supercomputers found their own ways around the limits of the components available to them.
The six machines here have since left service. Some influenced later designs; others tackled problems modern systems still face.
Ferranti Atlas — an address space larger than physical memory
One problem Atlas faced was the cost and speed of memory.
Magnetic core memory was fast but expensive and capacity-limited.
Drum storage held more data at lower cost, but took much longer to access. On Atlas, the drum access time was about 6 milliseconds, while the core memory cycle was about 1.9 microseconds. The numbers differ by more than a factor of 3,000, although access time and memory cycle time are…
