Any BEAM docs?

Bjorn Gustavsson <>
Fri Jan 9 18:49:42 CET 2004

Richard Carlsson <> writes:
> The external format used to be described by a document on Björn
> Gustavsson's page, but that link seems to be dead now. (Björn?)

My home page now has the following URL:

The file format document only describes the file format;
not the instruction set for Beam.

Some other useful files in OTP:

beam_lib.erl (in stdlib): utilities for reading and writing beam files. (in the compiler): number, name, and number of operands for
 all instructions + some comments.

To disassemble a loaded module to the instructions that are actually
executed, use erts_debug:df(Mod) (a disassembly file will be generated).

Björn Gustavsson, Erlang/OTP, Ericsson AB

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