This is an emulation of an Abacus which probably never existed.
It is based on a variant of the Salamis Tablet.
When the widget is started, it displays an abacus.
Click on the background to place a pebble on the abacus.
Click on a pebble to remove it from the abacus.
The number represented by the pebbles is displayed in decimal notation in the lower of the
two upper fields (the INPUT field).
Enter a number into the upper field (the ACCUMULATOR field), then press RETURN.
Corresponding pebbles are placed on the abacus.
The widget accepts javascript numbers.
Enter a number into the lower field (the INPUT field), then press RETURN.
Corresponding pebbles are placed on the abacus.
The widget accepts javascript numbers.
If the alt-key is down when the RETURN key is pressed, the number is added to the number in the accumulator and corresponding pebbles are placed on the abacus.
If the shift-key is down when the RETURN key is pressed, the number is subtracted from
the number in the accumulator and corresponding pebbles are placed on the abacus.
The shift-key takes priority if the alt-key and shift-key are both down.
There are on-screen shift and alt keys primarily for use on tablet computers that do not have these keys available. They act as locking keys.
This is used to move the pebbles to the edges of the abacus.
Pressing RETURN (without the alt-key or shift-key) in either the upper fields displays the peebles for that field.
Ancient Computers, Part I - Rediscovery, Edition 2 by Stephen Kent Stephenson, ISBN 9781490964379.
The New Abacus Web Widget is Copyright © 2020 Harry Whitfield (G6AUC).
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA