Intel HEX

Intel hexadecimal object file format, Intel hex format or Intellec Hex is a file format that conveys binary information in ASCII text form. It is commonly used for programming microcontrollers, EPROMs, and other types of programmable logic devices. 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. Common file extensions used for the resulting files are .HEX or .H86. 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.
History.
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 in order to replace the "paper-intensive" BNPF/BPNF format. Also, it served the purpose of easing the data transmission from customers to Intel for ROM production. The format was used to program (E)PROMs via paper tapes (in "Intellec Hex Paper Tape Format") or to control punched card-controlled EPROM programmers (through the "Intellec Hex Computer Punched Card Format").
Since 1975, it was also utilized by the MCS Series II floppy-disk based ISIS-II systems, using the file extension HEX.
Format.
Intel HEX consists of lines of ASCII text that are separated by line feed or carriage return characters or both. Each text line contains hexadecimal characters that encode multiple binary numbers. The binary numbers may represent data, memory addresses, or other values, depending on their position in the line and the type and length of the line. Each text line is called a "record".
Record structure.
A record (line of text) consists of six fields (parts) that appear in order from left to right:
Color legend.
As a visual aid, the fields of Intel HEX records are colored throughout this article as follows:
Checksum calculation.
A record's checksum byte is the two's complement of the least significant byte (LSB) of the sum of all decoded byte values in the record preceding the checksum. It is computed by summing the decoded byte values and extracting the LSB of the sum (i.e., the data checksum), and then calculating the two's complement of the LSB (e.g., by inverting its bits and adding one).
For example, in the case of the record , the sum of the decoded byte values is + + + + + + = codice_1, which has LSB value codice_1. The two's complement of codice_1 is , which is the checksum byte appearing at the end of the record.
The validity of a record can be checked by computing its checksum and verifying that the computed checksum equals the checksum appearing in the record; an error is indicated if the checksums differ. Since the record's checksum byte is the two's complement — and therefore the additive inverse — of the data checksum, this process can be reduced to summing all decoded byte values, including the record's checksum, and verifying that the LSB of the sum is zero. When applied to the preceding example, this method produces the following result: + + + + + + + = codice_4, which has LSB value codice_5.
Text line terminators.
Intel HEX records are separated by one or more ASCII line termination characters so that each record appears alone on a text line. This enhances legibility by visually delimiting the records and it also provides padding between records that can be used to improve machine parsing efficiency.
Programs that create HEX records typically use line termination characters that conform to the conventions of their operating systems. For example, Linux programs use a single LF (line feed, hex value codice_6) character to terminate lines, whereas Windows programs use a CR (carriage return, hex value codice_7) followed by a LF.
Record types.
Intel HEX has six standard record types:
Named formats.
The original 4-bit/8-bit "Intellec Hex Paper Tape Format" and "Intellec Hex Computer Punched Card Format" supported only record types and .
The "Extended Intellec Hex Format" additionally supports record type .
Special names are sometimes used to denote the formats of HEX files that employ specific subsets of record types. For example:
File example.
This example shows a file that has four data records followed by an end-of-file record:
 
 
Variants.
Besides Intel's own extension, several third-parties have also defined variants and extensions of the Intel hex format, including Digital Research (as in the so called "Digital Research hex format"), Zilog, Texas Instruments, Microchip, and c't. These can have information on program entry points and register contents, a swapped byte order in the data fields, and other differences.
The Digital Research hex format for 8086 processors supports segment information by adding record types to distinguish between code, data, stack, and extra segments.
Most assemblers for CP/M-80 (and also XASM09 for the Motorola 6809) don't use record type 01h to indicate the end of a file, but use a zero-length data type 00h entry instead. This eases the concatenation of multiple hex files.
Texas Instruments defines a variant where addresses are based on the bit-width of a processor's registers, not bytes.
Microchip defines variants INTHX8S (INHX8L, INHX8H), INHX8M, INHX16 (INHX16M) and INHX32 for their PIC microcontrollers.
Alfred Arnold's cross-macro-assembler AS, Werner Hennig-Roleff's 8051-emulator SIM51, and Matthias R. Paul's cross-converter BINTEL are also known to define extensions to the Intel hex format.