Mini-Calc

A simple, pleasant calculator

(res)

(op)

(err)

(swap)

⇔

Description

Mini-Calc is a simple calculator with a virtual memory model that includes a few registers and a main memory. Users can interact through both button clicks and keyboard input (special keybinds described below).

Input

User input goes directly into the input and operator (op) registers. Adding an operator moves the current input to the result register (res), or adds a zero if there is none. Computations can be performed when there is a value in (res), (op), and the input register.

Computations

If the calculator is in a valid state to perform a calculation, this can be initiated by pressing [=] or by adding another operator (chaining). Performing a computation stores the result in (res), as well as in memory (with the slight optimization that a calculation that is exactly the same as the most recent entry in memory is not stored again).

Storage

Values can be loaded from memory, input, or (res) to the (swap) register by clicking on them when (swap) is empty. Values can be moved from (swap) into input or (res) by clicking on them when (swap) is not empty. Values cannot be put into memory from (swap), nor can they overwrite input - it must be blank
( (res) may be overwritten).

These may be somewhat arbitrary constraints but they hold the calculator to the functionality specified in the assignment.

Errors

Performing an invalid calculation (such as divide-by-zero) will result in the error register (err) being set, and the calculator will enter an error state where the only valid input is Clear.

Clear will clear the values of all registers, including the (err) registor, resetting the calculator if it has entered an error state.

Keyboard Controls:

The calculator accepts number keys and operator keys. Some buttons do not have direct translations to the keyboard, and are bound as follows:

±: use s for "sign"
=: the = key works, as well as Enter
Clear: use c
Clear History: use h