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IBM mainframes that use operating systems in the z/OS and z/VSE families are always using some amount of Assembler applications code in the portfolios. This is a second generation programming language, considered to be a very “low level” technology, one layer above binary machine instructions, in the software stack.

The assembler language is the symbolic programming language that lies closest to the machine language in form and content. The assembler language is useful when:

  • You need to control your program closely, down to the byte and even the bit level.
  • You must write subroutines for functions that are not provided by other symbolic programming languages, such as COBOL, Fortran, or PL/I.

The assembler language is made up of statements that represent either instructions or comments. The instruction statements are the working part of the language and are divided into the following three groups:

  • Machine instructions
  • Assembler instructions
  • Macro instructions

In most cases, an Assembler system will need to be transformed to another language, like JAVA, C# or COBOL. However, for the Microsoft environments, there is a “Lift & Replatform” option for IBM’s Assembler code, both the development and runtime environments, offering a complete mainframe environment on .NET, with the added capability to use Microsoft’s Visual Studio for application development and maintenance.

UNISYS mainframes have a similar programming language called MASM (Meta-Assembler) on the ClearPath OS 2200 platform. There is no Assembler language available for the Burroughs ClearPath MCP Platform. In the case of MASM, there is no Replatform option available. However, MASM can be automatically transformed to a modern language such as C# or JAVA.

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