31 Dec
2014
31 Dec
'14
11:52 p.m.
On 2014-12-31 21:14, Clem Cole<clemc(a)ccc.com> wrote:
Jake - you have lots of help from others and using curses(3) is definitely
the right way to program.
But to answer your specific question about printf(string), according to
Chapter 3 (Programmer's Info) of my old VT-100 user's guide, I think what
is you are doing wrong is that "\033c" is not the ANSI clear to end of
screen command.
Right...
When I saw your message on my iPhone last night, the
cache said - wait that
can't be correct. But I could not remember why. So I had to wait until
I got back home today to look in my basement.
As I suspected, it's not an ANSI sequence. So are you running in VT-100
(ANSI) mode or VT52 mode? I ask because it is close to the VT52 cursor
right command which is actually: "\033C" but I do not remember is case
mattered.
Case do matter.
In VT52 mode you need to send the terminal:
"\033H\033J" to clear the
screen.
In ANSI mode, it becomes: "\033[1;1\033[0J"
Shorter form: "\033[H\033[J"
A few things to remember:
1.) Clear takes the current cursor position and clears from there to end of
X (where X depends on mode, and type of clear). So you need to move the
cursor to home position (aka 1,1).
Not really. It's way more advanced than that.
If we start with the generic clear screen, it is CSI Pn J
Where CSI can be expressed as ESC [ (or "\033[" in the same parlance as
above.)
Pn, then is an argument to the function, while J is the actual function
(clear screen in this case).
Now, Pn can cause many things:
0 Clear from cursor to end of screen
1 Clear from cursor to end of screen
2 Clear from beginning of screen to cursor
3 Clear whole screen
If no argument is given, the default is 0.
2.) VT-100's did not implement the full ANSI spec
like Ann Arbor, Heathkit,
Wyse etc. So there are a number of things that those terminals did
better. A really good reason to you curses(3) because all the knowledge is
keep in the termcap and as a programmer you don't need to worry about it.
Probably true. However, I'm not sure Ann Arbor or Heathkit did much
better. As far as I can remember, they were always more "weird", but I
might just be confused. However, curses(3) is definitely a good way of
not having to care about different terminal oddities.
3.) I saw sites were VT52 mode was sometimes preferred
because it was good
enough for most editing, and needed fewer chars to do manipulation. On
slow serial lines, this sometimes was helpful. That said, give me an AAA
any day. Like others, I still miss that terminal.:-)
Yeah, the VT52 was simpler, and had shorter control strings. But of
course, with the additional limitations that came with that.
Personally, I'd give an AAA or a Heathkit away if one was dropped on me.
A VT100 I would keep. :-)
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt(a)softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol