|Here is the rather splendid Anita 1233D,
one of the LSI range.
Despite the rather large collection of buttons
on what is otherwise a desk calculator, it is possible to figure out
their function fairly quickly without the use of a manual.
The three columns on the right represent the accumulation memories,
each has its own operational buttons to add, subtract and
clear, the diamond button recalls the value. above each
column is a lamp to indicate that the memory holds a value.
Additionally, the first two of these memories both have a toggle switch
above which can enable accumulation of other calculations. in this case
percentages and item multiplies respectively.
The only non simple operation performed by this model is square root.
notice the machine has twelve nixie digits (plus sign) and is accurate
to these twelve. indeed the INS button (stands for inspect) displays the
12 significant digits unfloated. ie it throws away any leading zeros.