10 Sep
2022
10 Sep
'22
2:27 a.m.
On Sep 9, 2022, at 12:39 PM, Nelson H. F. Beebe <beebe(a)math.utah.edu> wrote:
Paul Winalski and Bakul Shah commented on bit addressable machines
on the TUHS list recently. From Blaauw and Brooks' excellent
Computer Architecture book
http://www.math.utah.edu/pub/tex/bib/master.html#Blaauw:1997:CAC
on page 98, I find
>> ...
>> The earliest computer with bit resolution is the [IBM 7030] Stretch.
>> The Burroughs B1700 (1972) and CDC STAR100 (1973) are later examples.
>>
>> Bit resolution is costly in format space, since it uses a maximum
>> number of bits for address and length specification. Sharpening
>> resolution from the byte to the bit costs the same as increasing
>> address-space size eight-fold.
>>
>> Since almost all storage realizations are organized as matrices,
>> bit resolution is also expensive in time or equipment.
>> ...
And yet according to Wilner's article "the B1700 appears to
require less than half the memory needed by byte-oriented
systems to represent programs. Comparisons with word-oriented
systems are even more favorable."
Figure 9 shows sample sizes for Cobol, Fortran and RPG II programs
comparing B1700 code sizes with other systems. I was surprised to
see this but didn't look further.
https://dl.acm.org/doi/pdf/10.1145/1479992.1480060
From the same paper
DESIGN OBJECTIVE
Burroughs B1700 is a protean attempt to completely vanquish
procrustean structures, to give 100 percent variability, or
the appearance of no inherent structure. Without inherent
structure, any definable language can be efficiently used
for computing. There are no word sizes or data
formats—operands may be any shape or size, without loss of
efficiency; there are no a priori instructions—machine
operations may be any function, in any form, without loss
of efficiency; configuration limits, while not totally
removable, can be made to exist only as points of "graceful
degradation" of performance; modularity may be increased,
to allow miniconfigurations and supercomputers using the
same components.