From: Jim Witte (jswitte_at_bloomington.in.us)
Date: Sun Aug 15 2004 - 21:27:10 PDT
> Yes, I agree, those peeks and pokes are going to be the tricky bit
> since
> they are refering to particular memory locations;
> Looking at this code takes me down nostalgia lane....
Ah yes - been a long while since I did anything in Apple II basic -
I'd probably still be at it if I hadn't fried my IIe trying to test
switching on the different lines of the card slots with a damn battery
tester..
Anyway, the memory locations look like a register file of some sort -
it's most likely faster than using variables, which would have to have
their names hashed by the interpreter and then an access into a symbol
table. Or it might be a trig tablet of some kind. The pokes are in
the -163xx range, which are graphic control registers (switch between
screens, switch between high-res and low-res, etc - I forget the
specifics)
There's a list of a lot of the locations at
http://home.swbell.net/rubywand/csa2pfaq.html#004 I don't recognize
any of them, because they're in hex.. I think I got a lot of them from
the Apple II Reference Manual
I look at that code and I think - "Man, THIS is why goto is a bad
thing.." (But it does let you do really neat stuff in 1 line of code -
anybody else remember the "1-liner" contests in one of the main Apple
II magazines? I always thought those were cool.. Especially the
graphics ones.
Jim
-- This is the NewtonTalk list - http://www.newtontalk.net/ for all inquiries Official Newton FAQ: http://www.chuma.org/newton/faq/ WikiWikiNewt for all kinds of articles: http://tools.unna.org/wikiwikinewt/
This archive was generated by hypermail 2.1.5 : Sun Aug 15 2004 - 22:00:02 PDT