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freestylpolaris 11Oct2013 23:09

Little Man Computer Program Help
 
I am trying to write two different programs in LMC using an old assembly language. The first as is follows:



Writea LMC program that takes two inputs, a number to count down from, and the stepvalue (example: count down from 35 by 5), until it reaches zero. It should print each step, and the lastnumber before zero if the sequence doesn’t end on zero, but if the number goesto negative, that number should not be printed. Example output using 13 and 3 as inputs would be: 13, 10, 7, 4, 1. Example output using 12 and 3 as inputs wouldbe: 12, 9, 6, 3, 0.



I have tried something along the lines of this:



IN

STO 91

IN

STO 92

IN

STO 93

LDA 91

ADD 92

SUB 93

OUT

HLT



Which does not work



The second LMC program I am trying to write is as follows:



Writethe code to calculate the area and perimeter of a triangle. The program should take 3 inputs, which are,in order, the base, height, and the third side of the triangle. The code shouldproduce 2 values in the output box, the first number will be the area and thesecond, the perimeter. (Hint: you’ll probably want to use DAT statements tostore some values to start).



I do not even know where to start on this one.



Any help would be appreciated.



I found a working simulator at this website:








I also have some example codes to help:

Calculate perimeter & area - takes L & W as inputs
prints out perimeter first, then area.
00 LDA #01;
01 STA 99;
02 IN;
03 STA 98;
04 LDA #00;
05 STA 96;
06 IN;
07 STA 97;
08 ADD 97;
09 ADD 98;
10 ADD 98;
11 OUT;
12 LDA 96;
13 ADD 98;
14 STA 96;
15 LDA 97;
16 SUB 99;
17 STA 97;
18 SKZ;
19 JMP 12;
20 LDA 96;
21 OUT;
22 HLT;


MULTIPLIES TWO NUMBERS.
00 IN;
01 STA 99;
02 STA 97;
03 IN;
04 STA 98;
05 SUB 90;
06 STA 98;
07 SKZ;
08 JMP 12;
09 LDA 97;
10 OUT;
11 HLT;
12 LDA 97;
13 ADD 99;
14 STA 97;
15 LDA 98;
16 JMP 05;
90 DAT 001;

ADDS THE FIRST NUMBER INPUT TO ITSELF,
THEN SUBTRACTS THE SECOND INPUT FROM THE TOTAL
00 IN;
01 STA 90;
02 IN;
03 STA 91;
04 LDA 90;
05 ADD 90;
06 SUB 91;
07 OUT;
08 HLT;

ONE WAY OF COUNTING FROM AN INPUT DOWN TO ZERO
00 IN;
01 OUT;
02 SUB 98;
03 SKP;
04 JMP 06;
05 JMP 01;
06 HLT;
98 DAT 002;




SQUARING A NUMBER
00 IN; take input

01 STA 99; save value as a mulitiplier

02 STA 97; save value as multiplicand

03 SUB 90; subtract one from counter

04 STA 98; copy value to counter

05 LDA 97; load our accumulator number

06 ADD 99; Add original number

07 STA 97; store intermediate sum

08 LDA 98; Load counter

09 SUB 90; subtract one from counter

10 STA 98; Store counter value

11 SKZ; skip if counter is at zero

12 JMP 05; othewise, loop back to 5

13 LDA 97; load our squared number

14 OUT; Write output

15 HLT; stop

90 DAT 01; countdown value


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