Assembly Language using MARIE

Sample Marie Subroutine

Four Factor Multiplication using the Marie Architecture

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Sample Marie Instruction to Compute: Z = (A * B) * (C * D)

ORG  100 /Start Here  
Input  
Store A /Store Input as A  
Output  
Load A  
Store X /Store A in first parameter for subroutine  
Input  
Store B / Store Input as B  
Output  
Load  B  
Store Y /Store B in second parameter for subroutine  
JnS Multiply /Jump to multiplication subroutine  
Load Sum /Get Load the result  
Store  AB /AB = A x B  
Input  
Store C /Store Input as C  
Output  
Load C  
Store X /Store C in first parameter  
Input  
Store D /Store Input as D  
Output  
Load D  
Store Y /Store D in second parameter  
JnS Multiply /Jump to multiplication subroutine  
Load Sum /Get result  
Store CD /CD = C x D  
Load CD /Load product of CD  
Store X Store as first parameter for subroutine  
Load AB /Load product of AB  
Store Y Store as second parameter for subroutine  
JnS Multiply /Jump to multiplication subroutine  
Load Sum /Load product of AB*CD  
Store Z /Final Result Stored  
EndLoop, Load Z /Get full result  
Output /Output Final Result  
Halt /Terminate program

    /VARIABLES
A, Dec 0  
B, Dec 0  
C, Dec 0  
D, Dec 0  
X, Dec 0 /First parameter for subroutine  
Y, Dec 0 /Second parameter for subroutine  
Ctr, Dec 0 /Looping Counter  
One, Dec 1 /Constant for decrementation  
AB, Dec 0 /Product of AB  
CD, Dec 0 /Product of CD  
Z, Dec 0 /Final Result  
Sum, Dec 0 /Subroutine Product

    /MULTIPLICATION SUBROUTINE
Multiply, Hex 0 /Store return address  
Load Y /Load second parameter  
Store Ctr /Store as counter  
Clear /Clear sum  
Store Sum  
Loop, Load Sum /Load the sum  
Add X /Add first parameter  
Store  Sum /Store result in Sum  
Load  Ctr  
Subt One /Decrement counter  
Store Ctr /Store counter  
SkipCond  400 /Skip if counter is zero.  
Jump Loop /Continue subroutine  
JumpI Multiply /Done with subroutine, return  
END