MS-DOS File Types: Object Files and Load Modules In MS-DOS toolchains, what are the common extensions for relocatable object files and for load modules (executable images)?

Introduction / Context:
Classic DOS development uses a compile–link workflow. Compilers/assemblers produce relocatable object files that a linker converts into loadable executables. Recognizing standard filename extensions helps identify build artifacts and deployment outputs.

Given Data / Assumptions:

• Relocatable objects contain fixups and symbol information for the linker.
• Executable load modules are images the OS loader can run (.COM or .EXE under DOS).

Concept / Approach:
Assemblers/compilers emit .OBJ files. Linkers resolve symbols and relocations to produce .EXE (segmented) or .COM (simple, flat 64 KB) executables, both load modules for DOS.

Step-by-Step Solution:
Write source → assemble/compile → generate .OBJ.Link .OBJ plus libraries → produce .EXE or .COM.Run via DOS loader (COMMAND.COM) or shell.

Verification / Alternative check:
Tool manuals and historical DOS conventions document .OBJ as object and .EXE/.COM as executables, widely recognized across vendors (MASM, TASM, Microsoft C, Borland C, etc.).

Why Other Options Are Wrong:
B/C swap roles incorrectly.D uses a nonstandard .DAS extension.

Common Pitfalls:

• Assuming .COM and .EXE are interchangeable—.COM is limited and lacks headers.
• Confusing object files (.OBJ) with libraries (.LIB) or debug symbol files (.MAP).

Final Answer:
.OBJ and .COM or .EXE, respectively.