The Wang 600 Advanced Programmable Calculator uses "Register Notation" to perform operations. This differs from most modern calculators which use Reverse-Polish Notation (RPN) or Algebraic Notation. All operations on the Wang 600 are perform either on the display or between the display and a register.
There are 16 main registers, two of which have convenience short-cut keys on the main keyboard. These two are referred to as "left" and "right", since their keys are arranged on the left, or right, of the numeric entry keypad, which is in the middle. These keys perform STORE, RECALL, TOTAL (recall and clear), add, subtract, multiply, and divide, on their respective registers.
Further left and right are programming and general control keys. Most notable of which is the PRIME key which serves as general reset and clear-all. Pressing PRIME will set the display to 0.0000000000, clear any error conditions, and set the program counter (P.C.) to 0000. Pressing PRIME will generally restore the calculator to a known state and recover from any fault(s) encountered. All register values remain unchanged as a result of pressing PRIME.
On the back left of the keyboard area is a set of 4 pushbutton switches. These control the current mode of operation. Only one of these buttons may be depressed at a time. The farthest left is for "Run Mode", in which the calculator functions are accessible as well as running programs. Other modes include "Learn", "Learn and Print", and "List Program".
Next along the back panel is a red pushbutton labeled "Clear". This button will clear all 16 main registers to 0.0000000000.
The next 9 pushbuttons control the row of keys labeled "00" through "15". In general, these keys represent the 16 main registers. The first 7 pushbuttons are labeled "T", "+", "-", "×", "÷", "St", "Re" and represent the main operations that may be performed on register, as described for the Left and Right registers. In fact, the Left register is "15" and the Right is "14". Depressing one of the locking pushbuttons and pressing one of keys "00" through "15" will perform the labeled operation on that register.
The "f(x)" pushbutton is for calling subroutines in programs, and is described later.
The "Sp" (special) pushbutton locks independent of the other 8, and modifies the command code generated when pressing keys "00" through "15". It is used for creating program codes and is described later.
The remaining pushbuttons in that row all operate independently and provide their indicated function or feature. "Fl-Sc" switches between Floating Point or Scientific notation for the display. "Deg-Rad" selects whether trigonometric functions are performed using Degrees or Radians. The last two control the printer, turning it on/off and advancing the paper.
On the far right of the panel are the controls for the Cassette Tape Drive, used to save and load programs.
Here is an example of performing the arithmetic operation "5 + 6".
after which the display will show 11.000000000. In addition, the register "15" will contain the value 11. This can be verified by pressing PRIME (display returns to 0.0000000000), then pressing RECALL (left).
Values may be printed by turning on the printer and pressing the PRINT key. The number is printed in whatever format best fits, either floating point or scientific.
The calculator may be put in a trace mode, where all operations are printed. This is enabled by the two-key sequence known as "Alpha-Print". Press SHIFT, then "alpha" (the PRINT key's shifted value), then PRINT (unshifted). To turn off trace, press "alpha" "alpha" (SHIFT-PRINT, SHIFT-PRINT). In trace mode, any previous display content is printed along with a representation of the operation or key being pressed, and then another line is printed of the resulting display contents after performing the operation.