LOAD-BYTE etc, and order of bit numbering

[JONL at MIT-MC (Jon L White)]

    Date: 3 December 1979 22:46-EST
    From: David A. Moon <MOON at MIT-MC>
    Subject: LOAD-BYTE and DEPOSIT-BYTE
	. . . 
    dependency is that the arithmetic value of a fixnum containing a
    certain pattern of bits depends on the word length; if the bits were
    numbered from right to left it would not depend, provided only that the
    number of bits was small enough to fit in a word. 
Yea, this is the critical point as to why one has to have LDB as well
as LOAD-BYTE, namely that for READ/PRINT purposes one would like to have
a word-size-independent means of representing "bytes" (if there is no I/O,
using integers, why would one care what the numerical value of a "byte" is?)
    In NIL, we have the BITS data type, which is the preferred means for I/O 
of bytes;  only when converting from fixnums to BITS is there the ambiguity
of "scaling" and "ordering" (right-to-left, or left-to-right).   Likely
this means that LOAD-BYTE will be used only in explicitly machine-dependent
code; there are no usages of it in the NIL system now (only in the maclisp
virtual-machine support), but rather we depend on the conversions from
BITS to integers and vice-versa.
    By the bye, code is not made machine-independent merely by
using only  machine-independent primitives -  your whole machine may
be Godel'd into a bunch of numbers, to which you apply only standard
arithmetic primitives.