Monday, November 21, 2005

Hardware Going Full Circle

IBM System 360


Microsoft Xbox 360

Q: Why does a circle have 360 degrees?

A: Ancient peoples who lived in Mesopotamia (now southern Iraq) invented writing, and invented a 360-degree circle. Their calendar divided the year into 12 months of 30 days each, that is, 360 days.

My career in computing began in 1965, writing and executing tiny little BASIC programs, using a 110-baud Teletype with an UPPERCASE only keyboard, paper roll output, a side attachment for reading and punching papertapes, connected via a very clunky telephone modem to a GE mainframe computer running at MIT.

That mid Sixties timeframe also coincided with the introduction of Big Blue's big bang System 360's, named for their ability to serve all 360 degrees of computing requirements using a single hardware architecture.

Code written to run on one System 360 could automatically execute on any System 360. No re-compiling. No re-linking. Executable images were completely portable across a very scalable hardware line.

Hardware architecture circa mid-1960's was a VERY BIG DEAL. Fifteen years later, Digital Equipment Corp. (DEC), in its heyday, even included the 'A' from 'Architecture' as the second letter in its 'VAX' hardware name.

Nowadays we take hardware architecture more or less for granted. But you have to admit, it was a pretty huge breakthrough back when Gene Amdahl designed a set of machine instructions that separated the interface to the hardware from the underlying technology used to create the hardware. This allowed semiconductor technologies to advance along several fronts simultaneously while preserving customers' existing investments in software.


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