Re: Apple IIe and control characters in file names

[pblokland@planet.nl (Pim Blokland)]

In article <1e3uaic.817vj114mzu36N%dempson@actrix.gen.nz>,
dempson@actrix.gen.nz (David Empson) wrote:

> > As I recall on the IIe, you can use control characters in a filename which
> > aren't visible but are part of the filename.

Yes, only on DOS 3.x. Fortunately, ProDOS guard against this.

> Do you have any utility programs like Copy II+, Bag of Tricks or the
> Beagle Bros DOS 3.3 utilities (whose name I forget)?  You could use one
> of these to patch the filename to remove the control characters
> (replacing them with normal characters), or even just to find out what
> characters were used.

If David has Copy II+, he can just choose the "rename" item, because Copy
II+ does not require you to type in the original filenames. And there
certainly are other utilities which provide this feature.

However, to return to the original question, a quick and dirty patch that
displays all control characters as inverse uppercase is this (very quick,
very dirty):

$0300: CMP #$A0
$0302: BCS $0306
$0304: AND #$7F
$0306: JMP $FDF0

So, from the monitor, you type 

300:C9 A0 B0 02 29 7F 4C F0 FD

and then back in Basic, you type

POKE 54,0:POKE 55,3:CALL 1002

That will do the trick. Note that ALL control characters will be displayed
as inverse uppercase, including the returns at the end of lines. So this
routine will play havoc with your display, but it WILL show you the hidden
characters in the file names.
To return to normal, just press reset.

-- 
Groetjes, Pim

Millennium problem? What millennium problem?