********  Documentation for SCROFF.200  ********
            (c)1987  Wilson Van Alst
                       [76576,2735]


   As M100 users found out when they tried to use 1200 Baud external modems with
their machines, TELCOM communication speed is limited by relatively slow LCD 
scrolling routines in ROM.  For the 100, that limit is about 600 Baud unless you
disable scrolling.
   The T200 screen is faster, allowing 1200 bps communication with no LCD 
slowdown, but it will not handle 2400 Baud.
   Thus, SCROFF.200 -- a loader to install a bit of m/l code that turns TELCOM's
<F6> key into an on/off toggle for LCD scrolling.
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INSTALLATION:
   Download SCROFF.200 as a document and convert it to a BASIC program in the 
usual way.  It doesn't care what you call it, but for purposes of this 
discussion, we'll assume it's SCROFF.BA.
   When you run the program, the first menu page will tell you whether TELCOM's 
<F6> key is already in use.  If it is, you'll have to decide whether you want to
change its function.  Be advised: there may be ice on this road; so be sure your
important files are backed up before going further.
   If you choose the INSTALL option, it will check again for potential conflicts
and instruct you what to do if it finds one.  If there are none, it gives you a 
choice of where to put the 10 bytes of m/l code that perform the LCD toggle.
   At this point, options <1> or <2> will "hide" that code in an area where 
BASIC stores its <F> key functions.  I have installed the SCROFF code in a dark 
corner behind the BASIC "Menu" key -- but some people use that area for a 
routine that adds linefeeds to <CR>'s enroute to their printer or RS232 port.  
So, you're given the chance to install the SCROFF stuff behind the BASIC "Run" 
key, instead.  (In either case, the chores performed by those keys in BASIC will
not be changed; though you should be aware that re-defining the chosen key, 
after SCROFF code is installed, could invite disaster.)
   Options <3> or <4> of the INSTALL menu allow you to put the SCROFF routine at
the top of accessible RAM (it will load underneath any m/l programs currently 
installed, and HIMEM will be re-set to protect it), or at another address that 
you specify.
   Once the SCROFF code is installed, SCROFF.BA can be killed.
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REMOVAL:
   The first program menu in SCROFF.BA allows you to remove the m/l routine, 
wherever it's installed.  It will re-set the <F6> key in TELCOM to the coldstart
value (i.e., the key will do nothing).   Beware of the "Remove" option if 
another program is already using TERM's <F6>:  it will poke ten 0's into the 
middle of the other program's code -- with unredictable results.
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THANKS:
   To Tony Anderson for documenting the TERM <F6> hook at 62783.
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NOTES:
   The other key address in this routine is at EF0Bh (61195d).  The normal value
there is 0.  Any other value will disable scrolling.
   This is the m/l routine that is CALLed by the <F6> hook:

	PUSH	PSW
	LDA	EF0B
	CMA
	STA	EF0B
	POP	PSW
	RET

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