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OS/2 Help File
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1994-09-04
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5KB
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112 lines
ΓòÉΓòÉΓòÉ 1. Introduction ΓòÉΓòÉΓòÉ
E-Teller Calculator is a simple calculator which is not dissimilar to the
average (cheap) calculator one would generally find at one's local department
store. It does, however, have some features one would generally not find in
the average (cheap) calculator.
ΓòÉΓòÉΓòÉ 2. Using the Calculator ΓòÉΓòÉΓòÉ
To use E-Teller Calculator, press the appropriate numeric key. As each numeric
key is pressed, its corresponding number will appear in the display area of the
calculator. Press one of the operators (+ - / *) to perform the desired
calculation.
As each calculation takes place, the digits and operator will be appended to
the end of the calculation tape at the bottom of the calculator window; for
example:
1 + 2 = 3
2 * 3 = 6
For additional help on the calculator keys, see the Calculator keys topic.
ΓòÉΓòÉΓòÉ 2.1. Calculator keys ΓòÉΓòÉΓòÉ
This section describes some of the less apparent key functions and possible
corresponding keyboard equivalents.
Off (pushbutton) or O (keyboard)
turns the calculator off (effectively closing the application).
Backspace
removes the right-most number from the display area.
%
simulates a click on the % button.
Clr (pushbutton) or Esc or C (keyboard)
clears the display area when it is first clicked (at which point the
background colour turns bright red). When clicked a second time
(when the colour is bright red rather than dark red), the calculation
buffer is cleared and the button background colour returns to dark
red.
M (pushbutton) or M (keyboard)
alone does nothing. If a display number has been saved in the
calculator's memory (either by clicking on the M+ or M- buttons),
then the pushbutton caption will read M/r and an 'M' will appear in
the upper left-hand corner of the display. Clicking the M/r button
places the saved number into the display area and changes the M/r
caption of the pushbutton to M/c. Clicking the button at this stage
clears the calculator memory and removes the 'M' from the display
area.
M- (pushbutton) or Alt+M
subtracts the amount in the display from the calculator memory or
adds a negative value if the memory is empty. It also changes the M
caption from 'M' to 'M/r' as described above.
M+ (pushbutton) or Ctrl+M
adds the amount in the display to value in the calculator's memory or
places the number in the display into the calculator's memory. It
also changes the M caption from 'M' to 'M/r' as described above.
and (pushbutton) or Alt+Down and Alt+Up
respectively displays or hides the calculator tape and its
corresponding push buttons. When the tape is hidden, calculations
are not appended to it.
Clear (tape section)
erases the contents of the calculator tape.
Delete (tape section)
deletes the selected items from the calculator tape.
Print (tape section)
sends the contents of the calculator tape to the default printer.
Stamp (tape section)
appends a date and time stamp to the calculator tape, for example:
1 - 2 = -1
3 September 1994 (7:23pm)
The date format is system dependent, whereas the time stamp is not.
ΓòÉΓòÉΓòÉ 3. Notes ΓòÉΓòÉΓòÉ
When the calculator is turned off, the contents of the memory buffer, display,
and calculator tape are saved to the etcalc.ini file, in addition to the
location of the window and the visibility of the calculator tape section.
These are restored when the calculator is next invoked.
E-Teller Calculator traps syntax errors and displays the message Error - <error
message> where <error message> is the error reported by Rexx in the display.
These will generally be cryptic and of little use. If you consistently get
this sort of message, I would appreciate hearing about it. Particularly useful
would be a somewhat detailed description of what you did in order to get the
error message. The main purpose for trapping the errors is to avoid the
calculator from closing unceremoniously.
There is one error which E-Teller Calculator traps on its own. Dividing an
integer by zero is, of course, forbidden, and whenever a user inaverdently
attempts such a calculation, the error message, Error - divide by zero, is
displayed in the calculator's display area.
Note: In all cases, it would probably be a good idea to click on the Clr
button twice in order to clear the calculation buffer.