NAME¶
srec_intel - Intel Hexadecimal object file format specification
DESCRIPTION¶
This format is also known as the
Intel MCS‐86 Object format.
This document describes the hexadecimal object file format for the Intel
8‐bit, 16‐bit, and 32‐bit microprocessors. The
hexadecimal format is suitable as input to PROM programmers or hardware
emulators.
Hexadecimal object file format is a way of representing an absolute binary
object file in ASCII. Because the file is in ASCII instead of binary, it is
possible to store the file is non‐binary medium such as
paper‐tape, punch cards, etc.; and the file can also be displayed on
CRT terminals, line printers, etc.. The 8‐bit hexadecimal object file
format allows for the placement of code and data within the 16‐bit
linear address space of the Intel 8‐bit processors. The 16‐bit
hexadecimal format allows for the 20‐bit segmented address space of the
Intel 16‐bit processors. And the 32‐bit format allows for the
32‐bit linear address space of the Intel 32‐bit processors.
--address-length=2 |
“i8hex” |
16‐bit |
|
--address-length=3 |
“i16hex” |
20‐bit |
segmented |
--address-length=4 |
“i32hex” |
32‐bit |
linear |
The hexadecimal representation of binary is coded in ASCII alphanumeric
characters. For example, the 8‐bit binary value 0011‐1111 is 3F
in hexadecimal. To code this in ASCII, one 8‐bit byte containing the
ASCII code for the character '3' (0011‐0011 or 0x33) and one
8‐bit byte containing the) ASCII code for the character 'F'
(0100‐0110 or 0x46) are required. For each byte value, the
high‐order hexadecimal digit is always the first digit of the pair of
hexadecimal digits. This representation (ASCII hexadecimal) requires twice as
many bytes as the binary representation.
A hexadecimal object file is blocked into records, each of which contains the
record type, length, memory load address and checksum in addition to the data.
There are currently six (6) different types of records that are defined, not
all combinations of these records are meaningful, however. The record are:
- •
- Data Record (8‐, 16‐, or 32‐bit formats)
- •
- End of File Record (8‐, 16‐, or 32‐bit formats)
- •
- Extended Segment Address Record (16‐ or 32‐bit formats)
- •
- Start Segment Address Record (16‐ or 32‐bit formats)
- •
- Extended Linear Address Record (32‐bit format only)
- •
- Start Linear Address Record (32‐bit format only)
Record Mark |
Record Length |
Load Offset |
Record Type |
Data |
Check sum |
- Record Mark.
- Each record begins with a Record Mark field containing 0x3A, the ASCII
code for the colon (“:”) character.
- Record Length
- Each record has a Record Length field which specifies the number of bytes
of information or data which follows the Record Type field of the record.
This field is one byte, represented as two hexadecimal characters. The
maximum value of the Record Length field is hexadecimal 'FF' or 255.
- Load Offset
- Each record has a Load Offset field which specifies the 16‐bit
starting load offset of the data bytes, therefore this field is only used
for Data Records. In other records where this field is not used, it should
be coded as four ASCII zero characters (“0000” or
0x30303030). This field is two byte, represented as four hexadecimal
characters.
- Record Type
Each record has a Record Type field which specifies the
record type of this record. The Record Type field is used to interpret the
remaining information within the record. This field is one byte, represented
as two hexadecimal characters. The encoding for all the current record types
are:
- 0
- Data Record
- 1
- End of File Record
- 2
- Extended Segment Address Record
- 3
- Start Segment Address Record
- 4
- Extended Linear Address Record
- 5
- Start Linear Address Record
- Data
- Each record has a variable length Data field, it consists of zero or more
bytes encoded as pairs of hexadecimal digits. The interpretation of this
field depends on the Record Type field.
- Checksum
- Each record ends with a Checksum field that contains the ASCII hexadecimal
representation of the two's complement of the 8‐bit bytes that
result from converting each pair of ASCII hexadecimal digits to one byte
of binary, from and including the Record Length field to and including the
last byte of the Data field. Therefore, the sum of all the ASCII pairs in
a record after converting to binary, from the Record Length field to and
including the Checksum field, is zero.
Extended Linear Address Record¶
(32‐bit format only)
Record Mark (“:”) |
Record Length (2) |
Load Offset (0) |
Record Type (4) |
ULBA (2 bytes) |
Check sum |
The 32‐bit Extended Linear Address Record is used to specify bits
16‐31 of the Linear Base Address (LBA), where bits 0‐15 of the
LBA are zero. Bits 16‐31 of the LBA are referred to as the Upper Linear
Base Address (ULBA). The absolute memory address of a content byte in a
subsequent Data Record is) obtained by adding the LBA to an offset calculated
by adding the Load Offset field of the containing Data Record to the index of
the byte in the Data Record (0, 1, 2, ...
n). This offset addition is
done) modulo 4G (
i.e. 32‐bits from 0xFFFFFFFF to 0x00000000)
results in wrapping around from the end to the beginning of the 4G linear
address defined by the LBA. The linear address at which a particular byte is
loaded is calculated as:
(LBA + DRLO + DRI) MOD 4G
where:
- DRLO
- is the Load Offset field of a Data Record.
- DRI
- is the data byte index within the Data Record.
When an Extended Linear Address Record defines the value of LBA, it may appear
anywhere within a 32‐bit hexadecimal object file. This value remains in
effect until another Extended Linear Address Record is encountered. The LBA
defaults to zero until an Extended Linear Address Record is encountered. The
contents of the individual fields within the record are:
- Record Mark
- This field contains 0x3A, the hexadecimal encoding of the ASCII colon
(“:”) character.
- Record Length
- The field contains 0x3032, the hexadecimal encoding of the ASCII
characters “02”, which is the length, in bytes, of the ULBA
data information within this record.
- Load Offset
- This field contains 0x30303030, the hexadecimal encoding of the ASCII
characters “0000”, since this field is not used for this
record.
- Record Type
- This field contains 0x3034, the hexadecimal encoding of the ASCII
character “04”, which specifies the record type to be an
Extended Linear Address Record.
- ULBA
- This field contains four ASCII hexadecimal digits that specify the
16‐bit Upper Linear Base Address value. The value is encoded
big‐endian (most significant digit first).
- Checksum
- This field contains the check sum on the Record Length, Load Offset,
Record Type, and ULBA fields.
Extended Segment Address Record¶
(16‐ or 32‐bit formats)
Record Mark (“:”) |
Record Length (2) |
Load Offset (0) |
Record Type (2) |
USBA (2 bytes) |
Check sum |
The 16‐bit Extended Segment Address Record is used to specify bits
4‐19 of the Segment Base Address (SBA), where bits 0‐3 of the
SBA are zero. Bits 4‐19 of the SBA are referred to as the Upper Segment
Base Address (USBA). The absolute memory address of a content byte in a
subsequent Data Record is) obtained by adding the SBA to an offset calculated
by adding the Load Offset field of the containing Data Record to the index of
the byte in the Data Record (0, 1, 2, ...
n). This offset addition is
done modulo 64K (
i.e. 16‐bits from 0xFFFF to 0x0000 results in
wrapping around from the end to the beginning of the 64K segment defined by
the SBA. The address at which a particular byte is loaded is calculated as:
SBA + ((DRLO + DRI) MOD 64K)
where:
- DRLO
- is the LOAD OFFSET field of a Data Record.
- DRI
- is the data byte index within the Data Record.
When an Extended Segment Address Record defines the value of SBA, it may appear
anywhere within a 16‐bit hexadecimal object file. This value remains in
effect until another Extended Segment Address Record is encountered. The SBA
defaults to zero until an Extended Segment Address Record is encountered.
The contents of the individual fields within the record are:
- Record Mark
- This field contains 0x3A, the hexadecimal encoding of the ASCII colon
(“:”) character.
- Record Length
- The field contains 0x3032, the hexadecimal encoding of the ASCII
characters '02', which is the length, in bytes, of the USBA data
information within this record.
- Load Offset
- This field contains 0x30303030, the hexadecimal encoding of the ASCII
characters '0000', since this field is not used for this record.
- Record Type
- This field contains 0x3032, the hexadecimal encoding of the ASCII
character “02”, which specifies the record type to be an
Extended Segment Address Record.
- USBA
- This field contains four ASCII hexadecimal digits that specify the
16‐bit Upper Segment Base Address value. The field is encoded
big‐endian (most significant digit first).
- Checksum
- This field contains the check sum on the Record length, Load Offset,
Record Type, and USBA fields.
Data Record¶
(8‐, 16‐ or 32‐bit formats)
Record Mark (“:”) |
Record Length |
Load Offset |
Record Type |
Data |
Check sum |
The Data Record provides a set of hexadecimal digits that represent the ASCII
code for data bytes that make up a portion of a memory image. The method for
calculating the absolute address (linear in the 8‐bit and 32‐bit
case and segmented in the 16‐bit case) for each byte of data is
described in the discussions of the Extended Linear Address Record and the
Extended Segment Address Record.
The contents of the individual fields within the record are:
- Record Mark
- This field contains 0x3A, the hexadecimal encoding of the ASCII colon
(“:”) character.
- Record Length
- The field contains two ASCII hexadecimal digits that specify the number of
data bytes in the record. The maximum value is 255 decimal.
- Load Offset
- This field contains four ASCII hexadecimal digits representing the offset
from the LBA (see Extended Linear Address Record see Extended Segment
Address Record) defining the address which the first byte of the data is
to be placed.
- Record Type
- This field contains 0x3030, the hexadecimal encoding of the ASCII
character “00”, which specifies the record type to be a Data
Record.
- Data
- This field contains pairs of ASCII hexadecimal digits, one pair for each
data byte.
- Checksum
- This field contains the check sum on the Record Length, Load Offset,
Record Type, and Data fields.
Note: Care must be taken when the addresses with an record span the end
of addressing. The behaviour is different for linear and segmented addressing
modes.
- linear
- If a record starts just short of 2**32, and would finish after 2**32, the
later part of the record wraps around to address 0. TP 8n segment If a
record starts just for of a 2**16 boundary, and would finish after that
2**16 boundary, the later part of the record wraps around to address 0
within the same segment ( not the next segment).
The
srec_cat(1) program will never output records such as these, it will
always produce separate records on output.
Start Linear Address Record¶
(32‐bit format only)
Record Mark (“:”) |
Record Length (4) |
Load. Offset (0) |
Record Type (5) |
EIP (4 bytes) |
Check sum |
The Start Linear Address Record is used to specify the execution start address
for the object file. The value given is the 32‐bit linear address for
the EIP register. Note that this record only specifies the code address within
the 32‐bit linear address space of the 80386. If the code is to start
execution in the real mode of the 80386, then the Start Segment Address Record
should be used instead, since that record specifies both the CS and IP
register contents necessary for real mode.
The Start Linear Address Record can appear anywhere in a 32‐bit
hexadecimal object file. If such a record is not present in a hexadecimal
object file, a loader is free to assign a default execution start address.
The contents of the individual fields within the record are:
- Record mark
- This field contains 0x3A, the hexadecimal encoding of the ASCII colon
(“:”) character.
- Record length
- The field contains 0x3034, the hexadecimal encoding of the ASCII
characters “04”, which is the length, in bytes, of the EIP
register content within this record.
- Load Offset
- This field contains 0x30303030, the hexadecimal encoding of the ASCII
characters “0000”, since this field is not used for this
record.
- Record Type
- This field contains 0x3035, the hexadecimal encoding of the ASCII
character “05”, which specifies the record type to be a
Start Linear Address Record.
- EIP
- This field contains eight ASCII hexadecimal digits that specify the
32‐bit EIP register contents. The field is encoded
big‐endian (most significant digit first).
- Checksum
- This field contains the check sum on the Record length, Load Offset,
Record Type, and EIP fields.
Start Segment Address Record¶
(16‐ or 32‐bit formats)
Record Mark (“:”) |
Record Length (4) |
Load. Offset (0) |
Record Type (3) |
CS (2 bytes) |
IP (2 bytes) |
Check sum |
The Start Segment Address Record is used to specify the execution start address
for the object file. The value given is the 20‐bit segment address for
the CS and IP registers. Note that this record only specifies the code address
within the 20‐bit segmented address space of the 8086/80186. The Start
Segment Address Record can appear anywhere in a 16‐bit hexadecimal
object file. If such a record is not present in a hexadecimal object file, a
loader is free to assign a default start address.
The contents of the individual fields within the record are:
- Record Mark
- This field contains 0x3A, the hexadecimal encoding of the ASCII colon
(“:”) character.
- Record Length
- The field contains 0x3034, the hexadecimal encoding of the ASCII
characters “04”, which is the length, in bytes, of the CS
and IP register contents within this record.
- Load Offset
- This field contains 0x30303030, the hexadecimal encoding of the ASCII
characters “0000”, since this field is not used for this
record.
- Record Type
- This field contains 0x3033, the hexadecimal encoding of the ASCII
character '03', which specifies the record type to be a Start Segment
Address Record.
- CS
- This field contains four ASCII hexadecimal digits that specify the
16‐bit CS register contents. The field is encoded big‐endian
(most significant digit first).
- IP
- This field contains four ASCII hexadecimal digits that specify the
16‐bit IP register contents. The field is encoded big‐endian
(most significant digit first).
- Checksum
- This field contains the check sum on the Record length, Load Offset,
Record Type, CS, and IP fields.
End of File Record¶
(8‐, 16‐, or 32‐bit formats)
Record Mark (“:”) |
Record Length (0) |
Load Offset (0) |
Record Type (1) |
Check sum (0xFF) |
The End of File Record specifies the end of the hexadecimal object file.
The contents of the individual fields within the record are:
- Record mark
- This field contains 0x3A, the hexadecimal encoding of the ASCII colon
(“:”) character.
- Record Length
- The field contains 0x3030, the hexadecimal encoding of the ASCII
characters “00”. Since this record does not contain any Data
bytes, the length is zero.
- Load Offset
- This field contains 0x30303030, the hexadecimal encoding of the ASCII
characters “0000”, since this field is not used for this
record. In ancient times, i8hex used this for the start address
record.
- Record Type
- This field contains 0x3031, the hexadecimal encoding of the ASCII
character “01”, which specifies the record type to be an End
of File Record.
- Checksum
- This field contains the check sum an the Record Length, Load Offset, and
Record Type fields. Since all the fields are static, the check sum can
also be calculated statically, and the value is 0x4646, the hexadecimal
encoding of the ASCII characters “FF”.
Size Multiplier¶
In general, binary data will expand in sized by approximately 2.3 times when
represented with this format.
EXAMPLE¶
Here is an example Intel hex file. It contains the data “Hello,
World” to be loaded at address 0.
:0D00000048656C6C6F2C20576F726C640AA1
:00000001FF
REFERENCE¶
This information comes (very indirectly) from
Microprocessors and Programmed
Logic, Second Edition, Kenneth L. Short, 1987, Prentice‐Hall, ISBN
0‐13‐580606‐2.
http://en.wikipedia.org/wiki/Intel_HEX
COPYRIGHT¶
srec_cat version 1.58
Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
2009, 2010, 2011 Peter Miller
The
srec_cat program comes with ABSOLUTELY NO WARRANTY; for details use
the '
srec_cat -VERSion License' command. This is free software and you
are welcome to redistribute it under certain conditions; for details use the '
srec_cat -VERSion License' command.
AUTHOR¶
Derivation¶
This manual page is derived from a file marked as follows:
Intel Hexadecimal Object File Format Specification; Revision A, 1/6/88
Disclaimer: Intel makes no representation or warranties with respect to the
contents hereof and specifically disclaims any implied warranties of
merchantability or fitness for any particular purpose. Further, Intel reserves
the right to revise this publication from time to time in the content hereof
without obligation of Intel to notify any person of such revision or changes.
The publication of this specification should not be construed as a commitment
on Intel's part to implement any product.