Initializes the memory variable $v_k$ to have the value $n$. Number cards are used to specify constants used in the calculation and usually appear at the beginning of the program.
$\mathtt{+}$
Add
Sets the Analytical Engine into addition mode. When the operands are loaded into the ingress column, the two values are added together and placed on the egress column. If the result cannot fit in the number of digits available, the runup lever is set.
$\mathtt{-}$
Subtract
Sets the Analytical Engine into subtraction mode. When the operands are loaded into the ingress column, the value in $I_2$ is subtracted from $I_1$ and the result is placed on the egress column. If the result is negative, the runup lever is set.
$\mathtt{*}$
Multiply
Sets the Analytical Engine into multiplication mode. When the operands are loaded into the ingress column, the two values are multiplied together. Because the result of a multiplication is likely to be much larger than the input values, the output is stored in two columns that together act as a column with twice the usual number of digits. The first half of the result is stored in egress column $E'$ and the second half is stored in egress column $E$. As long as the numbers are small, you can ignore $E'$ and take the result from $E$, just as you would for addition and subtraction. The runup lever is not affected.
$\mathtt{/}$
Divide
Sets the Analytical Engine into division mode. The number contained in the combined columns $I_1'$ and $I_1$ is divided by the contents of $I_2$. The quotient is placed in $E'$ and the remainder is placed in $E$. If the quotient does not fit in its column or the divisor is zero, the runup lever is set.
$\mathtt{L}\ \ k$
Load
Copies the contents of variable $v_k$ into the appropriate ingress column, which is $I_1$ for the first such instruction and $I_2$ for the second $\mathtt{L}$ instruction in a pair. The contents of variable $v_k$ are not affected. If the $\mathtt{L}$ in the instruction is followed by a single quotation mark, the value is copied into $I_1'$.
$\mathtt{S}\ \ k$
Store
Stores the value from the egress column into variable $v_k$. If the $\mathtt{S}$ is followed by a single quotation mark, the value is taken from $E'$ instead.
$\mathtt{P}\ \ k$
Print
Outputs the value from variable $v_k$ to the printer.
$\mathtt{F}\ \ n$
Forward
Moves the card reader forward $n$ cards, skipping those operations. Note that the current card has already been read, so that the instruction $\mathtt{F}\ \ 1$ skips the next card.
$\mathtt{B}\ \ n$
Backward
Moves the card reader backward $n$ cards, allowing the machine to repeat previous operations. In counting the number of cards to move, it is important to keep in mind that the current operation has already been read.
$\mathtt{?F}\ \ n$ $\mathtt{?B}\ \ n$
Conditional
These operations are similar to the $\mathtt{F}$ and $\mathtt{B}$ operations except that the card reader moves only if the runup lever is set.
Attentions
Code/Program & Simulator
The simulator will be interrupted if the program executes more than $10^4$ steps.
The initial value of each column is $0$.
You can add Single-line comments to your code. The comment is started with "$\mathtt{//}$" and continues until the
end of the line. Please note that Multi-line comment is not supported.
If a step doesn't set the runup lever, it will reset the runup lever to $0$.
Loading a variable to an ingress column is NOT allowed before the mode is set to "+", "-", "*" and "/".
Loading a variable to $I_1'$ is NOT allowed if the mode is not set to "/".
Any comment and blank line will be ignored by the simulator, that is, a blank line in your code will not be
regarded as a real line in the program. So be careful when using $\mathtt{B}$, $\mathtt{F}$, $\mathtt{?B}$ and
$\mathtt{?F}$. You can make the most of the simulator to help you understand how it works on (Conditional) Forward and
Backward instructions.
If there is something wrong with the Online Judge(this may happen, especially when you submit a code which leads to a
TLE result), don't worry, and contact TAs as soon as possible.
Contact TAs
Feel free to ask TAs for help if you have any question or any unexpected error occurs.
