So you really haven't discovered anything special there. It is always the claim of the Watcom C++ compiler to produce the fastest code. This way, no 32-bit registers would or could be used.Īlso, two different compilers produce different binary code, some more optimal than others.

You should run the 16-bit program under DOS (this means your PC must boot DOS and run from there, and not run from a Windows 95 or NT session). Your other claim that you see 16 and 32-bit registers used when running a 16-bit application also messes up the test. So your 16-bit program has no Pentium instructions, since Pentium instructions are for 32-bit only.

The reason is that the 16-bit program has to work on 386 and 486 machines also. When you choose 16-bit mode, there is no way that it should produce Pentium instructions, even if you specified it.

Is anything due to the parallel processing in Pentium Processor? Is it possible due to the memory allocation and the floating point matrix manipulation,Ĭould you please kindly tell me the reasons?ĥ. Why this significant time reduction can occur?Ĥ. 32 bit issue, then could you please tell me the details If it is really due to the compiler, could you please tell me the reason?ģ. why my 32 bit program can run 50% faster than the 16 bit program?Ģ. Besides, the program has to perform a lot of floating point matrix manipulations.ġ. My program consists of a lot of memory allocation and reallocation functions like malloc() and realloc(). Than the time elapsed for the 16 bit program compiled by Borland. Both DOS programs are run in a Pentium II 400MHzįrom the measurement, the time elapsed for the 32 bit program that complied by DJGPP is about 50% LESS I run both programs and using the same method to measure the time elapsed. No optimization option is set at this time. Second, I use DJGPP to compile the same C program and create a 32 bit protected mode DOS program (.exe). I notice from the turbo debugger, the program uses 16 bit registers and also 32 bit registers like ax and eax. In this case, I set the following optimization optionsģ. I have a few questions regarding to the time elapsed in 16 bit Dos program and 32 bit Dos program.įirst, I use Borland C++ version 5.02 to compile my C program and create a 16 bit real mode DOS program (.exe).

Compile c program in dos number