[geeks] Geeky Valentine's day card

[Dave Kimmel]

On Fri, 15 Feb 2002, Bill Bradford wrote:
> ANy suggestions for someone who is mainly a systems person, does some
> programming, but wants to really learn computers at the chip architecture/
> assembly-language level?

My usage of microcontrollers hasn't gone this deep yet, but I know enough
about the architecture to know that learning the PIC architecture probably
wouldn't help you learn how a normal computer processor works.  As an
example, program and data are kept completely seperate - the program
memory is made up of 14-bit words, the data memory is 8-bit bytes, the
amounts vary depending on the specific PIC.

But it could be good for other things - if you wanted to figure out how
IDE worked, you could wire a microcontroller to a hard drive and make it
read and write data.  I built one device which watched the parallel port
for a specific string of data, it would sound a buzzer when it saw that
data.  Originally that was for work, but it got swallowed up by some
committie and hasn't been talked about since.  Serial interfacing is
tricky because of the timing, but some PICs have a built in UART, which
makes it a lot simpler.  Heck, there's one PIC that has a built in USB
port!

The route I took to get to the PIC was something like this:

* Commodore Vic-20 with some LEDs and switches hanging off of the user IO
port.  Controlled with PEEK and POKE in BASIC.
* Basic Stamp II (www.parallaxinc.com) - this is a module that uses a PIC
processor to interpret psudeo-code stored on an external EEPROM.
* OOPic (www.oopic.com) - this is another module that uses a PIC processor
to interpret psudeo-code stored on an external EEPROM.  This one features
object oriented programming and something called "Virtual Circuits" which
makes it pretty powerful.
* PIC 16xxx (www.microchip.com)

If you're interested in PICs specifically, take a look at "Programming and
Customizing the PICmicro Microcontrollers" by Myke Predko.  The copy I got
includes a printed circuit board which, with a few components and the
included software, makes a fairly cheap PIC programming tool.  Its
expensive though, around $80 Canadian.

comp.arch.embedded might be a good place to ask about this too - they deal
with embeeded processors ranging from tiny 8-pin microcontrollers all the
way up to 386 (or better) based computers that are working as embedded
controllers.

Ohh, just remembered this:  http://www.harrythebastard.org/page10.html
This guy built a computer to control things in his VW Camper using a 6502
processor, which is (IIRC) the same one that the Vic-20 uses.  Reading
through some of the things there might prove interesting, especially since
it applies to a CPU in a genuine computer, not a microcontroller.

> I'd go to austin community college and take some refresher courses, but
> god, they're packed and parking is horrible...

I know that feeling.  I took Basic Electricity I (I've been doing this for
years, but I wanted to learn the theory behind it all) and am currently
taking Visual Basic Programming (for work) at one of the colleges here.
Parking is terrible here too.

I've rambled on enough, hopefully you can get something helpful out of all
that.  :-)
-- Dave Kimmel
   criscokid at v-wave.com
   ICQ: 5615049