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From: roy@phri.UUCP
Newsgroups: comp.unix.questions,comp.edu,comp.lang.misc
Subject: Re: Teaching Assembler on VAX (BSD 4.3)
Message-ID: <2744@phri.UUCP>
Date: Sat, 13-Jun-87 21:03:28 EDT
Article-I.D.: phri.2744
Posted: Sat Jun 13 21:03:28 1987
Date-Received: Sun, 14-Jun-87 07:39:08 EDT
References: <965@killer.UUCP> <1762@megaron.arizona.edu>
Reply-To: roy@phri.UUCP (Roy Smith)
Organization: Public Health Research Inst. (NY, NY)
Lines: 30
Xref: utgpu comp.unix.questions:2470 comp.edu:395 comp.lang.misc:433
Summary: It *does* help one's education to get down to the bare iron

In <1762@megaron.arizona.edu> debray@arizona.edu (Saumya Debray) writes:
about how he first solved p-n junctions, then transistors, then logic
gates, then VLSI, but thinks the forest gets lost for the trees when you do
it that way.

	I don't know about that.  My education took roughly the same route
(as a EE, not a CS major).  It really helps sometimes to know what is going
on at the really low levels.  When configuring an ethernet, for example,
you have to deal with very high level concepts such as IP routing and very
low level concepts such as transmission line delays and impedence mismatch
reflections.  If you're getting double echos on a tty line, are you dealing
with a mis-set tty driver mode or capacitive coupling in the cable?

> The first computer I played with was an old PDP-11 that you booted by
> keying switches on the front panel.  A lot of fun, and I got to memorise
> the machine code for the loader fairly quickly, but I doubt it gave me any
> great insight into PDP-11 architecture.  

	Again, I disagree.  My first real intro to computer architecture
came through learning machine language on a M6800 (I'd love to get my hands
on a D2 kit again -- anybody have one laying around that they don't want?).
The 6800 isn't too different from a pdp-11 (or a Vax or 68020 for that
matter) and a lot of what I learned there still helps.  I don't think you
can really understand memory mapped I/O until you do a "sta $40A3" (or
whatever the address was) and see an LED segment light up.  Everytime I do
a "stty", I can still see the bits being stuffed into the ACIA CSR.
-- 
Roy Smith, {allegra,cmcl2,philabs}!phri!roy
System Administrator, Public Health Research Institute
455 First Avenue, New York, NY 10016