Re: Xy4 and Hex 1a

[cld@xxxxxxxx (Carl Distefano)]

Reply to note from Bill Troop  Sat, 15 Dec 2001
15:42:52 -0500

> But the hex 1a thing can be overcome in Xy4 by invoking on the
> command line "d 1a=1" (or is it d 1a=0? One of them is the
> default, and allows 1a to act as end of file; the other treats
> 1a as a character; ... You will normally want to be in expanded
> view for this kind of thing. With expanded view and d 1a set
> right, I think you can view any type of file in XyWrite.

With caveats and limitations. D 1A=1 enables reading past the
Ascii-26 EOF, but the display, even in eXPanded view, is likely to
be wrong. This is because XyWrite can't properly display the
characters it uses to do its internal housekeeping, i.e., the
"control characters" Ascii 0, 26, 253, 254 and 255. Ascii 26 either
doesn't show up at all or is transmogrified into another character
altogether. Ascii 0 and 253 control elements of the display and are
never visible. (SAving a file that contains Ascii 0's will cause
these characters to be stripped out, corrupting the file.) Ascii
254 and 255 combine with the next two bytes to form a 3-byte
character which displays instead of the three constituent characters
(and looks nothing like them). The bottom line is, if you really
want an accurate view of a non-text, non-XyWrite file, you've got to
use a hex viewer. XyWrite doesn't cut the mustard.

Still, D 1A=1 has its uses -- for example, to get a rough-and-ready
view of text embedded in a binary file. In that case, however,
always ABort the file after viewing. SAving or SToring it will
corrupt the file.

--
Carl Distefano
cld@xxxxxxxx
http://users.datarealm.com/xywwweb/