The question is attached, I need help to figure out what the hell this question is even asking us

 

The question is very clear. Fill in the blank boxes. This should be moved to homework.

 

You are required to run the program by hand and writing the contents of the Accumulator and the Stack at the same time.

 

I get that but how do you do this lol

 

it is simple right..first instruction pushes one to stack..then the added result is on top of stack.pop is not needed.tos is 4 now.lda loads a with 5.then with seven..push iot an muls multiplies 7 with three result is 21..popped to ac

 

Thanks! Whenever an ADD/MULS is done, it says that top two stack elements are added/multiplied, does that mean the second-top element disappears or stays there??

 

When multiplying two numbers in the stack, both numbers are popped from the stack, multiplied, and the result is pushed back onto the stack without touching the Accumulator, according to the description of the MULS instruction in the question.

However, I'm not sure if this is the expected result, or if LDA is supposed to push onto the stack as well, it normally doesn't.

Unless the question meant the stack was filled with 3s, or the LDA also pushed the value, which I doubt.

 

Ok thanks!

 

Be careful. I think the stack begins at Stack Base. So the first value of 3 should be at location Stack Base. The first PUSH instruction would put the value 1 at Stack Base + 1.

 

Be careful. I think the stack begins at Stack Base. So the first value of 3 should be at location Stack Base. The first PUSH instruction would put the value 1 at Stack Base + 1.

I was wondering about those labels. The stack is labeled wrong for getting the intuitive concept across.

I decided to go with "looks good". Teacher may disagree.

 

It depends which way the stack grows. It can grow towards lower addresses or higher addresses. This is just a pseudo computer as a teaching model.

 

Ok thanks!

Also, the Zero Flag in the non-existent status register would be set on the last two instructions, it's sometimes faster to check the zero flag than to compare to zero after an operation.

 

Yeah the stack + 3 is the top of the stack, so stack base initially contains value 3. Also, ADD/MULS apparently does not delete the 2nd top element...it just takes result and overwrites top element (according to Professor for this problem only).

 

Yeah the stack + 3 is the top of the stack, so stack base initially contains value 3. Also, ADD/MULS apparently does not delete the 2nd top element...it just takes result and overwrites top element (according to Professor for this problem only).

I was thinking in RPN, the best calculator OS around, from HP. Give a 35s a try!