IBM Basic assembly language and successors

The IBM Basic assembly language and successors is a series of assembly languages and assemblers made for the IBM System/360 mainframe system and its successors through the IBM Z.

The first of these, the Basic Assembly Language (BAL), is an extremely restricted assembly language, introduced in 1964 and used on 360 systems with only 8 KB of main memory, and only a card reader, a card punch, and a printer for input/output, as part of IBM Basic Programming Support (BPS/360). The Basic Assembler for BAL was also available as part of Basic Operating System/360 (BOS/360).

Subsequently, an assembly language appeared for the System/360 that had more powerful features and usability, such as support for macros. This language, and the line of assemblers that implemented it, continued to evolve for the System/370 and the architectures that followed, inheriting and extending its syntax. Some in the computer industry referred to these under the generic term "Basic Assembly Language" or "BAL". Many did not, however, and IBM itself usually referred to them as simply the "System/360 Assembler Language", as the "Assembler" for a given operating system or platform, or similar names. Specific assemblers were known by such names as Assembler E, Assembler F, Assembler H, and so forth. Programmers utilizing this language, and this family of assemblers, also refer to them as ALC (for Assembly Language Coding), or simply "the assembler".

The latest derived language is known as the IBM High-Level Assembler (HLASM).