Re: Apple II text files (again)

[v-paulk@microsoft.com (Paul Kearns)]

In article <dd80148@pro-gumbo.cts.com> tgeer@pro-gumbo.cts.com (System Administrator) writes:
>In <93102.093250F0O@psuvm.psu.edu> <F0O@psuvm.psu.edu> writes:
>>20 D$ = CHR$(4)
>    ^^^^^^^^^^^^
>
>There's your problem.  Under Dos 3.3 this should read: D$=CHR$(13) + CHR$(4)
>                                                      This is not necessary
>under ProDOS.

Or allowed, as I remember.  It seems like I had to go through and modify a
bunch of my Applesoft programs when ProDOS first came out because ProDOS
thought that 

	PRINT CHR$(13)CHR$(4)"OPEN FILE"

was not an operating system call.  After all, an OS call was any string
that began with CHR$(4), and CHR$(13)CHR$(4) isn't CHR$(4), right???  I can
remember being frustrated about that, especially when I didn't use a
variable, but had everything littered in PRINT statements like that.
Serves me right....

Once cool thing about DOS 3.3's conception that CHR$(13)CHR$(4) started a
DOS command was that you could do

	10 REM <33 spaces here>^DFP

Then when someone LIST'd the program, it'd print the first fourty
characters and then a carriage return (CHR$(13)) -- this was when most
Apple's still were only 40 colums wide --, then a Ctrl-D (CHR$(4)), plus a
DOS command "FP".

The end result was that a line like that would make your program
unLIST'able, since LIST'ing it would do a DOS "FP" that cleared memory!  Of
course, all they'd need to do is "LIST 11-", but still.  If you were
feeling malicious, you could of course use 

	10 REM <33 spaces>^DINIT HELLO

Which would, of course, INITialize their disk on a LIST...  Heh heh....

Cool.  Weird DOS tricks.  I feel like Bert Kersey.

>tom geer: tgeer@pro-gumbo.cts.com

Paul Kearns
v-paulk@microsoft.com