DESIGN AND IMPLEMENTATION OF A VISUAL DEBUGGER FOR THE INTEL-8085 MICROPROCESSOR

Abstract

Debugging programs involves repeating several steps : executing test programs_, detecting errors, inves• tigating their causes and correcting them. The most time consuming, difficult step is the detection and investigation of errors. A debugging tool should show the program's static and dynamic behaviour so the programmer can easily understand what the program is do ing and how it is being executed. The task undertaken in this thesis is developmen of a Visual debugger for Intel 8085 assembly language programs VD8085 . 0 The main intention is to make the execution of programs as much visible as possible. VD8085 uses graphics to show the static and dynamic behaviour of the program execution. The input is an 8085 assembly language program. The screen is divided into six windows. One window is for all the registers, stack pointer and program counter. All these values are displayed in HEX. Second window is for showing the contents of PC or the contents of memory of -which the user wants to check the contents. Third window shows the contents of stack. Only four top most enteries are shown on the screen in this window. Fourth window is for all the P] flags. Current values of all these flags are displayer The fifth window displays the assembly language program under execution. Sixth window is the working window in which the user selected commands are displayed. The debugging system designed has three software components : the cross-assembler, the simulator and the debugger itself. Running on an IBM PC/XT under MSDOS, tike system is invoked in three stages. The cross-assembler, assembles 8085 assembly language mnemonics and pseudo-operations to provide the m/c language form of the program which is then executed by the simulator-debugger combine. The debugging commands are issued and carried out as the program executes.