Path: utzoo!utgpu!watmath!clyde!att!pacbell!ames!haven!ncifcrf!nlm-mcs!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn )
Newsgroups: comp.sys.apple
Subject: Re: Long and short integers
Message-ID: <9009@smoke.BRL.MIL>
Date: 29 Nov 88 13:54:10 GMT
References: <8811251119.AA18101@crash.cts.com>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) )
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 35

In article <8811251119.AA18101@crash.cts.com> pnet01!pro-simasd!pro-exchange!rich@nosc.mil writes:
>As far as the concept of "first" is concerned, there are a fairly substantial
>number of independently developed applications which are doing (or rather,
>allowing the Apple to do) parallel <-> serial conversions, with a reasonably
>high level of success.  There must be *some* sort of "starting point" that's
>fairly widely accepted as first|leading|initial|whatever you like!!

There are standards such as RS-232-C for serial bit order, based on the
order in which the selector bars had to be triggered on mechanical
teleprinters in order to set up for a given character.  (In fact any
serial link-level protocol will have to specify how to interpret the
time sequence of bits.)

I don't 100% recall whether the least significant bit of the "ASCII
code value" was sent first or last for the teleprinters (I think it
was first).  The hardware could have been designed either way,
which is in fact my point: most-significant is not necessarily the
"first" bit although in a serial context it could be, depending on
the conventions that apply in the specific case.

>I was always under the impression that "address" arithmetic and "data"
>arithmetic were not only handled differently, but didn't even use the
>same registers.

But the assembly-level PROGRAMMER has to be able to mix these, for
example to perform arithmetic on a pushed value on the stack that
was placed there as a return address by the hardware when a
subroutine call was made.  The chip internals are irrelevant.

>[give example of] storing a 16-bit value somewhere with a single instruction

	LDA	something
(with extended mode active)  After all, this WAS a 65816 discussion
originally.  I don't know at what point you thought it became 8-bit
specific.