Re: running .system files from BASIC

[dalloff@gcfn.org (Dave Althoff Jr)]

Don Bruder (dakidd@sonic.net) wrote:
: In article <LfqdnZdcsZ_xJO3dRVn-iQ@comcast.com>,
:  "Bill Garber" <willy46pa@comcast DOT net> wrote:

: > You need the Semi-Colon after D$ otherwise
: > it'll think D$"-xxxxxxxx.SYSTEM" is all one
: > variable.

: I'm not going to swear to it, but I think that's incorrect. Seems to me 
: I remember writing code either way, since Applesoft didn't care whether 
: the semicolon was there or not.

: There were a couple special cases that I can't recall right now (mostly 
: involving unexpected ways the parser saw things) that made it a really 
: good idea to use the semicolon between items in a print list, but aside 
: from the "gotcha" cases, I'm pretty sure it's optional.

I've never seen problems like that with this form of print statement.  But
I have seen oddball problems when the parser would do exactly as I told it
instead of what I wanted it to do.  Consider this:

nnn IF B = A THEN 40

...will result in a ?SYNTAX ERROR while...

nno IF A = B THEN 40 

...will work fine.  Reading the listing reveals all:

LIST nnn-nno
nnn IF B = AT HEN 40
nno IF A = B THEN 40

There are other situations where using a particular variable name can
cause the parser to misread the variable name as part of a reserved word. 
It's because the Applesoft parser is programmer-friendly and doesn't care
about such things as spaces and certain punctuation.  The easiest way to
stay out of trouble is to use two-byte variable names (although certain
ones...AT, FN, GR, IF, ON, OR, and TO are Applesoft reserved words. 
Oddly enough, FP is a DOS command and therefore not a reserved word...)
which fill the parser's variable space and prevent it from tacking on the
first byte from the next token.

I just looked up the reserved words in the Applesoft ][ BASIC Programming
Reference Manual, but because I am at work, I don't have an Apple ][
handy...I just saw something else in here.  It says...

     (minimum line number is 0, maximum is 65529)

Now wait a minute...I thought the highest allowable Applesoft line number
was 63999...anybody know for sure?

--Dave Althoff, ][.
  Whose collection of utility subroutines start at 60000...
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