[TUHS] 2^n-bit operands (Was reviving a bit of WWB)

8-bit bytes? I give the credit to the IBM Stretch, aka 7030, and the Harvest attachment they made for NSA. For autocorrelation on bit streams--a fundamental need in codebreaking--the hardware was bit-addressable. But that was overkill for other supercomputing needs, so there was coarse-grained addressability too. Address conversion among various operand sizes made power of two a natural, lest address conversion entail division. The Stretch project also coined the felicitous word "byte" for the operand size suitable for character sets of the era. With the 360 series, IBM fully committed to multiple operand sizes. DEC followed suit and C naturalized the idea into programmers' working vocabulary. The power-of-2 word length had the side effect of making the smallest reasonable size for floating-point be 32 bits. Someone on the Apollo project once noted that the 36-bit word on previous IBM equipment was just adequate for planning moon orbits; they'd have had to use double-precision if the 700-series machines had been 32-bit. And double-precision took 10 times as long. That observation turned out to be prescient: double has become the norm. Doug