The Assembly Language Processor (ALP) is a macro assembler that runs under the 32-bit OS/2 operating system. ALP is designed as a functional replacement for the Microsoft Macro Assembler (MASM). It accepts the full syntax of the MASM 5.10 assembly language, which is a subset of the MASM 6.00 high-level directive language. It also understands the complete Intel 80X86 instruction set, including the MMX extensions. ALP creates standard Object Module Format (.OMF) files that can be linked to produce DOS or OS/2 executables and can generate line number debug information compatible with IBM's Presentation Manager Debugger. In addition, this tool offers a rich set of command-line options, as well as a comprehensive listing file with user-tailored formatting, allowing a visual perspective not possible with other assemblers.

ALP translates assembly language source files (typically having a file-name extension of .ASM) into object (.OBJ) files. The LINK386 utility can then be used to combine multiple object files into a single executable file, dynamic link library, or device driver.

While ALP is designed as a functional replacement for the Microsoft MASM assembler in terms of source code compatibility, it does not use the MASM command-line syntax. ALP uses a free-form syntax, has a comprehensive set of options, and allows assembly of multiple input files with a single command-line invocation.

For each corresponding input source file, ALP can produce the following types of output files:

• Object (.OBJ) files, which contain program data and executable code.
  
• Listing (.LST) files, which document the results of the assembly.
  
• Message (.MSG) files, which can contain all error, warning, and informational messages produced during the assembly.

See the ALP Programming Guide and Reference for more information on ALP. Online help is also available from the command line for all ALP options.