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8085 Simulator Help &Documentation

8085 Simulator 1.2  Screenshot

Help & Documentation

1)  Keyboard shortcuts

ESC : RESET

   F1    : EXAM MEMORY

   F2    : GO

   F3    : EXECUTE

F4     : EXAM REG

  (0-9)  :Just guess !!

  (A-F) :what? you guessed this one too !!

2) How to load and execute a program?

Consider a simple assembly program to add 2 numbers. In this program first we load the accumulator with 67h, load register B with 12h and then add the contents of register B to the accumulator. The result is stored in the accumulator.

MVI A, 67

MVI B, 12

ADD B

HLT

The opcodes for this program is given below. (Refer the instruction.chm, 8085 instruction set to convert 8085 mnemonics to hex opcodes).

3E

67

06

12

80

76

Given Below is the procedure to execute this program on the 8085 simulator:

Step 1: Reset

Press the <RESET> button on the 8085 form (or F1 Key on the keyboard).

Step 2: Choose the address to save the program

Let us store the program starting at address 8000H. Press <exm Mem> button and then press the buttons 8,0,0 and 0.

After this press the <NEXT> button, next press 3E button on the 8085 simulator followed by <Next> button. Similarly press the buttons for all opcodes followed by <Next>. 

<RESET>

<exm Mem> 8000

<Next>

 3E

<Next>

 67

<Next>

 06

<Next>

 12

<Next>

 80

<Next>

 76

<Next>

Step 3: To Execute a program

Press the <GO> button on the 8085 simulator followed by the starting address of the program 8000 and then press the <Exec> button to begin execution. The program execution is clearly displayed in the debugForm.

<Go>

8000

<Exec>

3) Delay and time

   To give a delay of 100ms use the instruction: CALL  4444.

    For 500ms delay use the instruction: CALL 5555

    For 1s delay use the instruction : CALL 6666

Note: The delay routines you normally use for 8085 will not produce appropriate delay on the 8085 simulator. The reason is the simulator works on different processors with different speeds, and on different platforms and also different programs running in the background hence it is very difficult to simulate the time delay due to instruction iterations. Therefore instead of the delay routines which you normally use, use the above instructions to (call the system routines to) produce the delay.

4) Address field and data field

To display data in the data field
           First the data to be displayed in the data field should be stored at the memory address 8FF1 and then use the instruction: CALL 044C.

To display data in the address field
        First the data to be displayed in the address field should be stored at the memory address 8FEF(lower byte) and 8FF0(higher byte) and then use the instruction :  CALL 0440.

REMEMBER: use HLT instruction to terminate the program if you want to display

      the data in the address field . Use of RST 5 instruction clears both the address and the

      field.(also this is the behavior of most 8085 microprocessor college kits)

THANK YOU

          Thank you for using this program and special thanks to people who have written to me and reported various bugs and suggested to include new functionalities.

Please send me your suggestions, feedback and report any bugs to vikas@vikaspatel.org or thedemonlovers@yahoo.com .