TASK 1 Using the following: LMC:
Complete the three programs outlined
below. Follow, the instructions
carefully and make a note about what is happening.
TASK 2
In Google.doc screen dump the output and
label with call-outs
Features:
- Uses the same instruction set as theatkinsn.yorku.ca version.
- Loads and saves assembly language programs as text files.
- Supports labels for both branching and data.
- Supports indentation making code easier to follow.
- Does not remove the original code when assembly takes place.
- Features both a STEP and a RUN mode and the ability to switch
between them while a program is running.
- In STEP mode, the 'Little Man' explains the next instruction before
it is executed.
- Allows assembly language programs to be pasted directly into the
program window.
- Allows programs to be copied from either text window for use in
reports.
- Run mode is faster than the atkinsn.yorku.ca version.
- Allows line annotation such as: loop LDA value1 // Start of main loop.
- Produces an assembly language version without labels or annotation,
makes it easier to understand the assembled code in RAM.
- INPUT
is via an 'input device' rather than the keyboard, allowing integer values
in the range -999 to 999.
- Multi-line output makes it easier to follow programs that have more
than a single output.
- 'Machine Code' instructions in RAM can be edited directly (the U button
will update any changes to the current instruction).
1.
The following program will demonstrate the input
and output instructions of the LMC. The first instruction will copy a
three-digit number from the In Box to the accumulator, and the second
instruction will copy the value of the accumulator to the Out Box.
Program
INP
OUT
HLT
What you should do
1. Click on the
"LMC Simulator Applet" link to start the LMC simulator.
2. Clear the Message Box
and all of the LMC mailboxes -- click the "Clear Messages" button and
the "Clear" button if necessary.
3. Copy the three-line
program above and paste it into the Message Box
4. Click on the
"Compile Program" button.
5. Click on the
"Run" button.
6. When prompted, enter
a three-digit number in the "In-Box", and press the "Enter"
button.
What you should see
- After the program is
compiled, you should see 901 in mailbox 0 and 902 in mailbox 1. The
Program Counter should start at 0 (click on "Reset" if
necessary).
- When you click on
"Run" or "Step", the Message Box will describe the
actions of each instruction.
- After the INP instruction,
the Accumulator has a copy of the value in the In Box.
- After the OUT instruction,
the Out Box has a copy of the value in the Accumulator.
- The final value of the
Program Counter is 2. This mailbox holds 0 - the machine code
instruction that tells the LMC to stop executing your program.
2. LMC Load and Save Instructions
The following program will demonstrate the load and save
instructions of the LMC.
Program
INP
STA FIRST
INP
STA SECOND
LDA FIRST
OUT
LDA SECOND
OUT
HLT
FIRST DAT
SECOND DAT
What you should do
1.
Click
on the "LMC Simulator Applet" link to start the LMC simulator.
2.
Clear
the Message Box and all of the LMC mailboxes -- click the "Clear
Messages" button and the "Clear" button if necessary.
3.
Copy
the eleven line program above and paste it into the Message Box
4.
Click
on the "Compile Program" button.
5.
Click
on the "Run" button.
6.
When
prompted, enter three-digit numbers in the "In-Box", and press the
"Enter" button.
What you should
see
- After the program is compiled, you should see
from mailbox 0 to 7 the instructions 901, 309, 901, 310, 509, 902, 510,
902. The Program Counter should start at 0 (click on
"Reset" if necessary).
- DAT is the tenth and eleventh instruction of your
program, so they refer to mailboxes 9 and 10 (0-indexed counting).
FIRST and SECOND are the identifiers that have been declared to represent
these mailboxes in the assembly language program.
- When you click on "Run" or
"Step", the Message Box will describe the actions of each
instruction.
- After the first INP instruction, the Accumulator
has a copy of the first value entered in the In Box.
- After the STA instruction, the input value is
copied from the Accumulator to mailbox 9 -- 3 means STORE and 09 refers to
the mailbox to store into.
- After the second INP instruction, the Accumulator
has a copy of the second value entered into the In Box (use a different value
than the first).
- After the second STA instruction, the second
input value is copied from the Accumulator to mailbox 10.
- After the LDA instruction, the Accumulator is
reset to the first input value. This value has been retrieved from
mailbox 9 -- 5 means LOAD and 09 refers to the mailbox to load from.
Note: since your Accumulator can only work on one value at a time, you
have to repeatedly STORE and LOAD values from memory to keep them from
getting erased by the next operation.
- After the OUT instruction, the Out Box has a copy
of the value in the Accumulator -- the first input value
3. LMC Add and Subtract Instructions
The following program will demonstrate the add and subtract
instructions of the LMC. Note: The Accumulator (calculator) in the LMC is
only designed to work with non-negative three-digit numbers. Mathematical
operations which produce values greater than 999 or less than 000 can cause
undefined effects to occur.
Program
INP
STA FIRST
INP
ADD FIRST
OUT
INP
SUB FIRST
OUT
HLT
FIRST DAT
What you should do
1.
Click
on the "LMC Simulator Applet" link to start the LMC simulator.
2.
Clear
the Message Box and all of the LMC mailboxes -- click the "Clear
Messages" button and the "Clear" button if necessary.
3.
Copy
the ten line program above and paste it into the Message Box
4.
Click
on the "Compile Program" button.
5.
Click
on the "Run" button.
6.
When
prompted, enter three-digit numbers in the "In-Box", and press the
"Enter" button.
What you should
see
- After the program is compiled, you should see
from mailbox 0 to 7 the instructions 901, 309, 901, 109, 902, 901, 209,
902. The Program Counter should start at 0 (click on
"Reset" if necessary).
- DAT is the tenth instruction of your program, so
it refers to mailbox 9 (0-indexed counting). FIRST is the identifier
that has been declared to represent this mailbox in the assembly language
program.
- When you click on "Run" or
"Step", the Message Box will describe the actions of each
instruction.
- After the first INP instruction, the Accumulator
has a copy of the first value entered in the In Box.
- After the STA instruction, the input value is
copied from the Accumulator to mailbox 9.
- After the second INP instruction, the Accumulator
has a copy of the second value entered into the In Box (try values that
will lead to three and four digit sums).
- After the ADD instruction, the Accumulator value
represents the sum of the two input values -- 1 means ADD and 09 refers to
the mailbox where the value to be added to the Accumulator is stored.
- After the third INP instruction, the Accumulator
has a copy of the third value entered into the In Box (try values that
will lead to positive and negative results).
- After the SUB instruction, the Accumulator value
represents the difference between the two input values -- 2 means SUBTRACT
and 09 refers to the mailbox where the value to be subtracted from the
Accumulator is stored.
EXTENSION
Complete the 4, 5 and 6 and put the output into your workbook:
http://www.yorku.ca/sychen/research/LMC/
