**>> TOON v 1.2 <<**

TOON12.COM records what is on the computer screen. It is useful
to anyone who writes about, or needs to record, video computer 
output.  TOON.COM takes its name from the carTOON of your screen 
which it places in a disk file.  The file of screens, also called 
Toon, is a standard ASCII text file.  It can be further edited for 
any purpose by using a text editor.  The screens can also be printed, 
or inserted in any other document. This is an advantage of making 
a disk file instead of sending screens directly to the printer: 
the screen data is available for all uses.

                           Use of TOON

A>toon12<cr>

A>                                           TOON.COM loads, then
                                             returns you to CP/M.

Now you use your computer normally.  A part of TOON.COM is 
resident in your RAM, residing just below your CCP.  You can 
easily tell that TOON.COM is loaded, because it will remind you 
every time you Warm Boot:

A>^C
Toon = ^_

Instead of the usual "Warm Boot" message, you see a notice 
containing's TOON.COM's signal to save the screen; ^_ (control 
underline).  Because this character can be generated from the 
keyboard, but is used extrememly rarely for anything else, it can 
serve as the "save screen" signal.  To activate TOON.COM, just 
type ^_ (On my keyboard, ^_ and ^- are the same).

After ^_ is typed, you see nothing onscreen, because TOON.COM has 
intercepted the ^_ and not written it to the screen.  But the
disk drives should start, then stop again when the screen file is 
finished.  If the output file Toon does not exist, TOON.COM 
creates it.  If it does exist, the new screen is added onto the 
existing screens with just a crlf in between.  As many successive 
screens as desired may be appended to the file Toon.

When you no longer need TOON to save screens, just cold boot the 
computer (press the reset button).  The ensuing reconstruction of 
the CP/M system will turn TOON off.

                         How TOON Works

TOON.COM first loads into the TPA (program area) of your computer 
like other CP/M programs, at 0100h.  But its first actions are
unusual, in that it redirects one of the standard functions of
the computer BIOS (the CONIN, or console input function) to the
site where TOON will soon be, below the CCP.  Then, as its last
gesture, TOON relocates its screen-saving code to the high memory
site, and returns you to CP/M.  The screen saver remains active 
until overwritten by something else, or until a cold boot (reset) 
repoints the CONIN jump to its normal destination.

TOON's 627-byte watchdog in high memory takes all calls to the 
normal CONsole INput function, checking every character. When it 
finds a ^_ in CONIN, it uses the system's status port to bank-
switch back and forth from video to normal memory.  TOON reads the 
video memory and writes it into the file, Toon, on the currently 
logged disk. To keep TOON small, no disk error messages are 
issued.  This means that, for example, if the disk becomes full, 
TOON will write part of a file without notifying you.

                     Using TOON Effectively

TOON really can write all screen information, which means that 
all the blank spaces onscreen will be represented in the file as 
blank characters (20h). Thus lines in the output file Toon can be 
wide (80 chars), and just fit on a normal printer. Eighty 
character lines will not fit comfortably onscreen in your text 
editor if it (eg, Wordstar) tries to put other characters on the 
same line. Monitor routines (the programs which run screens) also 
will add lf to 80 character lines, and thus Toon would 
(incorrectly) appear to have blank lines in its text when TYPE'd 
from CP/M. In order to avoid this distortion of the text, and 
still preserve all characters onscreen, TOON deletes the last 
character of screen lines, but only if the last character is a 
blank.  Lines which contain information in the 80th column will be 
preserved, and will have a ghost line inserted after them when 
TYPE'd to the screen.

                       Different Computers

By their very nature, screen-saving programs are very machine 
dependent.  Every computer uses a different method to store its 
video information. TOON is no exception. The distributed version 
reads video memory in the early Kaypro II (sometimes called the 
'83 model, before graphics).  TOON will not work as is, even on 
other Kaypros which do not use bank-switched video memory.  
However, the machine-specific part (called rdvid) has been 
isolated and clearly marked in TOON.ASM.  If you know how your 
computer uses screen information, you can delete rdvid and drop 
another routine into its place, and reassemble TOON.COM.  If you 
do this and lengthen the program, check that the new TOON still 
allows enough space below the ccp for itself (endmv-begin+1 in 
the line labeled launch0 must be less than the offs equate).

            Possible Interaction with Other Programs

TOON's watchdog sits in a fairly safe place, but it can be 
overwritten by programs which keep data or code in high 
memory.  This is true of programs compiled with Turbo Pascal 
using its default End address, for example.  If you get bizarre 
behavior, or lockup, when TOON and another program are combined, 
this is almost surely what is happening. The same thing can 
happen if you have an extra-luxurious ccp, because TOON assumes 
that the ccp start = bios start - 1600h, as for standard 64k CP/M 
2.2. This will give trouble as soon as you type A>Toon because 
you will overwrite an essential piece of your CP/M system. It is 
easy to get around this difficulty by experimentally changing the 
"offs" equate in TOON.ASM, then recompiling. As "offs" grows, 
TOON will relocate further and further down in memory, leaving 
more room above it for your CP/M system or other programs.

                    TOON Reduces the TPA Size

There is one other consideration.  TOON loads at the hard-coded 
address we have just talked about, below the ccp in high memory.  
But it alters the BDOS jump to point to itself.  Other programs 
loaded after TOON, if they look at the BDOS jump to see how much 
program space is available, will automatically load under TOON, 
and not overwrite it.  To make the best use of this deception, 
load TOON first to set the BDOS signpost.

                           **>>  <<**

If you prefer that assembly language be spoken only in Toyota 
factories, take heart!  You can use TOON without understanding 
any of the above if you have a standard CP/M 2.2 system, like the 
one distributed with the Kaypro II.

Good luck with TOON! It is often the best way to show other 
people what your computer does.

June, 1985                                   Mike Yarus
                                             2231 16th Street
                                             Boulder, CO 80302

                                             Compuserve 73145,513