Terminal customization for z80emacs is accomplished by using the 
program METERM.COM

In order to keep the program as small as possible, thus allowing 
you to edit as much data as possible, I assumed that there are only 
two kinds of terminals in the world: ANSI and ASCII.

I also restricted z80emacs to using just three different terminal 
control sequences: direct cursor motion, clear-to-end-of-line, and
clear-whole-screen.

In order to keep the program as small as possible, I didn't use a 
fancy termcap package ( though, if I had one, I could have 
initialized it in an overlay, so my feeble excuse doesn't hold
much water ). Another consideration is that, once z80emacs is 
installed, it will "always" be used with one and only one 
terminal type, and reading a termcap file would take time
( a slightly better argument; METERM.COM is like an overlay 
that only executes once ).

That's what meterm is about: it reads ME.SYM and ME.COM, 
reports what it finds, gets input from the user, and writes new 
data to ME.COM; meterm is very careful to check that ME.COM 
matches ME.SYM, by the way, so nothing cango rwong.

Just in case, meterm tells you where the ansimove() routine is 
found, so that you can patch it if you need to; in case you need 
to do so, the binary distribution includes TELANSI.C, TELANSI.ASM,
TELANSI.O, and my apologies...

Most people shouldn't need to patch.

If your terminal is like a PC or like a VT100, it's ANSI; otherwise, 
it's almost sure to be ASCII.

The sequences for clear-to-end-of-line and clear-whole-screen are 
simply sent out as they appear in the termctrl[] table.

The problem is direct-cursor-motion; that's why there's a variable 
called "ansiterm", that tells the ansimove() subroutine whether 
it's dealing with an ANSI or ASCII terminal.

If ASCII, the cursor-motion sequence is probably 4 bytes long, 
escape, '=', space, space; the first two characters are sent 
out as is, the third character is added to the binary line 
number and sent out, the fourth character is added to the 
binary column number and sent out. This works as is for televideo, 
wyse, qume, ADM, etc., etc; for a few others, you may have to modify 
the second character.

    If the sequence isn't 4 bytes long, if the column number needs 
    to be sent first, you'll have to patch.

If ANSI, the cursor-motion sequence as stored by z80emacs is 4 
bytes long: "1b 5b 3b 48". The first two are sent out as is,
then the line number is sent out in decimal, then the third is 
sent out, then the column number in decimal, then the fourth.

In both cases, you can specify the sequence as being longer than 
4 bytes in order to send out "padding" bytes.

You may think this is a monumental kludge, but I think it's an
elegant simplification. Nyahh, nyaah, so there!

----Ralph Betza, October 1, 1991


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