Machine coding the programs-microprocessor, Assembly Language

Machine Coding the Programs

So far we have describe five programs which were  written  for hand coding  by a programmer. In this, we will now have a deep look at how these programs may be  translate to machine codes. In Appendix, the instruction set along with the Appendix is presented. This Appendix is self-explanatory to hand code mostly of the instructions. The V,S W, D, MOD, REG  and R/M  fields are appropriate decided depending upon the data types, addressing mode and the registers  used. The table shows the details about how to select these fields.

Most of the instructions either have particular opcodes or they may be decided only by setting the V,S, W, D, REG, MOD and R/M fields suitably but the critical point is  the calculation of jump addresses for intra segment branch instructions. Before beginning the coding of call or jump instructions, we will see some simpler coding examples.

Example :

MOV BL, CL

For hand coding this instruction, first we will have to note down the following features.

(i) It sets in the register/memory to/from register format.

(ii) It is an 8-bit operation.

(iii) BL is the destination register and CL is a source register.

Now from the feature (i) by using the Appendix, the op code format is given below.

1485_mcp.jpg

If d =1, then transformation of data is to the register shown by the REG field, for example the destination is a register (REG). If d = 0, the source is a register shown by the REG field. It is an 8-bit operation, therefore w bit is 0. If it had been a 16-bit operation, the w bit would have been 1.From referring to given table to search the REG to REG addressing in it, for example the last column with MOD 11. According to the Appendix when MOD is 11, the R/M field is treated as a REG field. The REG field which is used for source register and the R/M field are used for the destination register, if d is 0. If d =1, the REG field is utilized for destination and the R/M field is used to indicate source. the complete machine code of this instruction comes out to be now.

code    dw       MOD   REG    R/M

MOV BL, CL 1 0 0 0 1 0 0 0     1   1   001    0 1 1= 88 CB

Posted Date: 10/12/2012 6:47:59 AM | Location : United States







Related Discussions:- Machine coding the programs-microprocessor, Assignment Help, Ask Question on Machine coding the programs-microprocessor, Get Answer, Expert's Help, Machine coding the programs-microprocessor Discussions

Write discussion on Machine coding the programs-microprocessor
Your posts are moderated
Related Questions
SUB: Subtract :- The subtract instruction subtracts the source operand from destination operand and result is left in the destination operand. Source operand might be memory locati

Code for Reading Flow & Generating LED Output The code starts with the scanning of the PORT 3, for reading the flow status to check for various flow conditions and compare to

1- Write an assembly program that:   a- Defines an array of 10 (word type)elements;   b- Finds out the number of negative elements   c- Calculate the summation of the posi

AAD stand for what??

Develop a suitable schematic circuit diagram of your system showing the interface between the PIC16F84 and the existing mains light & switch, including 5V derivation from the 240V

Write a 68hc11 assembly language program which generation of the following waveforms connected to your DAC i)   Square wave ii)  Saw tooth waveform iii) Sine wave iv) U

AND: Logical AND: This instruction bit by bit ANDs the source operand that might be an immediate, or a memory location or register to the destination operand that might be a memor

Write an Lc-3 assembly language program to read in a sequence of single-digit positive integers from the keyboard(one integer per line) until the sentinel value of 0 is reached and

write an assembly program to display triangular star like shape

Internal Architecture of Microprocessor : The architecture of 8086 provides a number of improvements over 8085 architecture. It supports a, a set of 16-bit registers ,16-bit AL