CALCULATOR

     The CALC.COM module is a resident utility that allows you to perform
basic arithmetic operations on real numbers (1.00000000e-99 ...
9.99999999e+99). The calculator considers as meaningful the first 9 digits
of the mantissa. Numbers can be presented both in usual and exponential
form. For example, all figures shown below have correct representation:

     Number                               Calculator's presentation
  ----------------------------------------+------------------------
  .0678                                   | 0.0678
  1.4786e4                                | 14786
  0.000000123456789                       | 0.000000123456789
   .00000003                              | 3e-8
   1345.27e47                             | 1.34527e50
   2e5                                    | 200000
   0.00000000000000000000000000003        | 3e-28
   1023000041000000000000000000000000000  | 1.02300004e36

     When you install the calculator the following message appears on the
screen:

              +---------------------------------------------+
              | Resident calculator v.2.01 by A.Zudin.      |
              | (C) PhysTechSoft Ltd. 1993.                 |
              | Press Alt+Tab to call                       |
              +---------------------------------------------+

     To invoke the calculator press simultaneously [Alt-Tab]. To exit
press [Esc].

     You can position the calculator panel in any part of the screen using
the arrow keys.  To do this use [Alt-M] to see a message "Moving" appear in
the calculator's right upper corner.  You can move the calculator about the
screen using arrow keys.  Having chosen the position press [Enter]. At
subsequent calculator session it will appear where you left it off.

     When editing the input string in the calculator panel you may use the
following keys:

[left arrow]  - moves the cursor one position to the left,
[right arrow] - moves the cursor one position to the right,
[Home]        - moves the cursor to the beginning of the string,
[End]         - moves the cursor to the end of the string,
[Del]         - deletes the character  under  the  cursor,
[Backspace]   - deletes the character to the left of the cursor,
[Enter]       - inputs the string and starts computation.

     If a red rectangle starts blinking after you enter your string, that
means that you made a mistake in your mathematical expression.  Edit the
string and correct your mathematics, before pressing [Enter] again.

     The calculator panel can be scrolled. If the input string is too large
to fit into the panel the text automatically moves up to by one line to
permit continued inputting. Whatever was input prior to that is saved and
can be brought up for editing with the help of the above commands.

     A command stack is used in the calculator. By pressing up and down
arrow keys you can select one of the eight previous commands  to  use  it
again without re-typing. The state of the calculator is saved when you exit
and is restored when you call it again.

     If you need to temporarily store results of intermediate calculations
you can make use of register variables.  Each variable is denoted by a
letter of the latin alphabet (case does not matter) and is a zero by
default. To assign a value to a variable type in

  <variable>=<expression>, for example:
   a=2(3+4(5+6)1.035e10/5.175e9(7+8)+1)

     2648 will appear on the screen.  Now a=2648 and if you input, i.e.
a/6784, then the screen will show 0.390330189. It means that now you can use
this variable as a number, i.e., it may be an argument in all your
operations.

     In numerical expressions you can use both decimal and hexadecimal
numbers. The hexadecimal number should end in "h" (and preceded by "0" to
avoid mistaking it for an alternate, if it does not start with a numerical
number), i.e. 3e8h, 2710h, 2100h, BUT 0b800h, 0a4h, 0f374bh.  The working
band for hexadecimal numbers -0ffffffffh...+0ffffffffh. Any number beyond
this band is considered non-hexadecimal. If all you entered is a number it
will be converted to the other numerical system:  from hexadecimal to
decimal and vice versa. The conversion will be performed only if the number
is not in decimal form and fits within hexadecimal operations band.