

By convention, ' //' is often used for comments. It allows to store other related information in the same file (and even the same line), a facility used by various software development utilities to store symbol tables or additional comments, and third-party extensions using other characters as start code like the digit ' 0' by Keil, ' $' by Mostek, or ' !', ' ' #', ' \', ' &' and ' ' by TDL. However, as this was a little known part of the specification, not all software written copes with this correctly. In fact, very early versions of the specification even asked for a minimum of 25 NUL characters to precede the first record and follow the last one. All characters preceding this symbol in a record should be ignored.

Beginning in 1975, the format was utilized by MCS Series II ISIS-II systems, using the file extension HEX. In 1973, Intel's "software group" consisted only of Bill Byerly and Ken Burget, and Gary Kildall as an external consultant. It was also used to specify memory contents to Intel for ROM production. The Intel hex format was originally designed for Intel's Intellec Microcomputer Development Systems (MDS) in 1973 in order to load and execute programs from paper tape. The HEX file is then read by a programmer to write the machine code into a PROM or is transferred to the target system for loading and execution. Common file extensions used for the resulting files are. Some also use it as a container format holding packets of stream data.

In a typical application, a compiler or assembler converts a program's source code (such as in C or assembly language) to machine code and outputs it into a HEX file. It is commonly used for programming microcontrollers, EPROMs, and other types of programmable logic devices and hardware emulators. Intel hexadecimal object file format, Intel hex format or Intellec Hex is a file format that conveys binary information in ASCII text form.
