Re: A very quick, informal survey

From: Roger Willcocks (rkww_at_rops.org)
Date: 04/10/04 

Date: Sat, 10 Apr 2004 01:48:51 +0100

"Steven O." <null@null.com> wrote in message
news:og49709khdbf1rr09thq6ko7vc8vpk9glm@4ax.com...
> I write documentation. The company I'm working for is developing a
> product that transmits data from one computer to another, and the
> order or sequence of data transmission is important.
>
> We need to specify whether the data transmission and storage is
> Big-endian or Little-endian. I've argued that, in addition to stating
> which it is, we need to explain what these terms mean. The
> programmers claim that any programmer worth their salt will know what
> these terms mean.
>

Many programmers who claim they understand these terms don't understand the
detail. The straightforward argument that 'the lowest 8 bits go in the
lowest-addressed (highest-addressed) memory for the multibyte data we are
accessing' is all well and good, but consider sending those bytes down a
serial line one bit at a time: do you send the most - or least - significant
bit first?

I had a similar problem with a one-bit-per-pixel display: what order,
exactly are the bits, obviously ordered left to right on screen, in
addressable memory?

See http://www.rdrop.com/~cary/html/endian_faq.html - and take note in
particular of the apparently mixed endianness of pdp11 and vax long and
floating point representations.

The best advice I can give is for you is to explain exactly which bits (and
bytes) go where and ignore the endian jargon.

BTW I have an electronic engineering degree + 23 years professional
programming experience (starting with pdp11 assembler as it happens). 

--
Roger
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