From: davis@pacific.mps.ohio-state.edu ("John E. Davis")
Subject: 8 bit clean implies what?
Date: Sat, 6 Feb 1993 18:22:29 GMT
Hi,
I have a few questions regarding the meaning of 8 bit clean editors.
As I understand it, an editor which is 8 bit clean can display ALL 256
characters on the output device. That is, the character should not be mapped
to a displayable representation (i.e., ascii char 1 to two character sequence
^A). So for example, if character 235 corresponds to the greek letter alpha
on the output device, an alpha should appear when char 235 is sent. In
addition, the editor should be able to take ANY 8 bit character form the input
device and display it. That is, if the input device is capable of sending the
char 235 (alpha), then the char should be deisplayed as above. Is this
correct?
On my PC, the char 255 do not display anything on the screen (just a space).
255 is also -1 when converted to signed char and usually denoted end of file
or something special like that. Is it just a coincidence that 255 displays
nothing on my PC or is this a general feature? Should I make any assumptions
regarding 255? I would like to reserve it for my own purposes.
Finally, are characters with the hi bit set (>= 128) ever involved in keymaps?
This might seem like a silly question but for my purposes, it is the most
important question. I tend to think of keymaps as involving only 7 bit chars,
e.g., escape map. But is any known case of a keymap where the prefix character
has the high bit set?
In case you are wondering, I am working on an editor (JED). Recently, I
released version 0.80 which I thought to be 8 bit clean, but in retrospect, it
is not. I hear people say ``Just treat ALL characters the same!''. However, I
am concerned with memory usage on PCs and I would like to cut corners wherever
I can. Berfore I release the next version (0.81), I want to make SURE that I
get the 8 bit thing correct.
I appreciate any comments on the subject. Thank You.