A Student's View of the Apple //
By Moninya Roughan
Copyright (c) 1994 Apple Users' Group, Sydney
Republished from Applecations, a publication of the Apple Users' Group, Sydney, Australia.
I am not a total imbecile when it comes to computers, however, in my family I would be considered by far, the least computer literate. Some how with the excitement of life around me I never seemed to make it past the very simple 'HELLO' programs that my brother and I started writing when we first got our Apple ][+ way back in 1982.
So it came as a shock to me when enrolling for second year university at UNSW that I was faced with the prospect of learning about the Apple. For a start the nature of the course was masked by calling it "Computer Applications in Experimental Science" - a physics subject. The subject description in our handbook manages to put it nicely. It says "An introduction to the internal structure, operating and interfacing of computers... instruction execution in a processor; machine language code and instruction sets..." Whatever that means. Thus I enrolled, totally oblivious to what lay ahead of me.
In our first tutorial class, the tutor stood before me and along with all his comments about his receding hairline not reflecting his age, he tried to convince me that in mathematics we use calculus which is hundreds of years old, so there's nothing wrong with using Apple IIs (only a mere 17 years old) to learn about the inner workings of a computer.
In our household, the war of Apples versus IBMs has been raging for a while, however there was never a mention of Apples being... dare I say it... obsolete. This has been defended strongly at University.
It wasn't long before I was set up in my bedroom with a little Apple //c and a disk of my very own. The fun was about to begin. About half way through the course we were instructed to take the disk out and "CALL -151". Strange things started appearing on the screen:
300: FF 00 FF 00 FF etc..
Translated it actually says "the martians are coming", but my lecturer tried to convince me otherwise.
This was my first introduction to assembler, machine language, or whatever the hip name is currently.
Gradually the mystery surrounding all these numbers unfolded (not without a little help from my brother - at last he was finally useful for more than just a good argument).
At first I found the concept more than a little bizarre, I mean, I am a marine scientist, not a computer freak. So what's with all the numbers anyway?
I jumped in the deep end, trying to write a program to add two numbers whilst having no idea that there was more to addressing modes than "absolute addressing". Needless to say it took a little longer than I originally intended.
Branching was a lot of fun - advanced programming I call it. The easiest one to remember I found was BNE - go to Brisbane. It's then just a matter of working out where Brisbane is!
A concept i'm still coming to grips with are flags in the 'P' (processor status) register. To me a flag says "3 minute gun", "shortened course", "race abandoned" etc. How on earth could a one or zero be a flag, indicating something really important? I mean who cares if the V flag is set to one and an overflow occurred? Like I said, I'm a marine scientist.
I confronted my tutor one particularly exasperating day, demanding to know why it was necessary for me to learn how to program a computer when I could just as easily cajole, bribe, or, if the worst came to the worst, pay someone else to do it for me.
Despite him not being able to give me what I would consider a satisfactory answer, I am persisting in the subject. I never knew something could be so simple and yet so complicated at the same time.
I doubt i'll ever really use assembler again after i've finished this course, but I will be able to sleep cosy at night knowing that I actually understand what goes on inside a 6502 processor.
Enough said, it's time to go sailing....

THIS CONTENT COPYRIGHT © 2007, APPLE MACINTOSH USERS' GROUP, SYDNEY
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