Revision A, 1/6/88

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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. 


1. Introduction

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. 
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 033H) and one 8-bit byte 
containing the ASCII code for the character 'F' (0100-0110 or 046H) 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 ma ny 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 records 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) 


2. General Record Format

| RECORD  |     LOAD     |         |         |  INFO   |         | 
|  MARK   |    RECLEN    | OFFSET  | RECTYP  |   or    | CHKSUM  | 
|  ':'    |              |         |         |  DATA   |         | 
  1-byte       1-byte      2-bytes   1-byte    n-bytes   1-byte 

Each record begins with a RECORD MARK field containing 03AH, the ASCII 
code for the colon (':') character. 
Each record has a RECLEN field which specifies the number of bytes of 
information or data which follows the RECTYP field of the record.  Note 
that one data byte is represented by two ASCII characters.  The maximum 
value of the RECLEN field is hexadecimal 'FF' or 255. 
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 030303030H). 
Each record has a RECTYP field which specifies the record type of this 
record.  The RECTYP field is used to interpret the remaining information 
within the record.  The encoding for all the current record types are: 

'00' Data Record 
'01' End of File Record 
'02' Extended Segment Address Record 
'03' Start Segment Address Record 
'04' Extended Linear Address Record 
'05' Start Linear Address Record 

Each record has a variable length INFO/DATA field, it consists of zero 
or more bytes encoded as pairs of hexadecimal digits.  The 
interpretation of this field depends on the RECTYP field. 
Each record ends with a CHKSUM 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 RECLEN field to and including the last 
byte of the INFO/DATA field.  Therefore, the sum of all the ASCII pairs 
in a record after converting to binary, from the RECLEN field to and 
including the CHKSUM field, is zero. 


3. Extended Linear Address Record (32-bit format only)

| RECORD  |     LOAD     |         |         |         |         | 
|  MARK   |    RECLEN    | OFFSET  | RECTYP  |  ULBA   | CHKSUM  | 
|  ':'    |    '02'      | '0000'  |  '04'   |         |         | 
  1-byte       1-byte      2-bytes   1-byte    2-bytes   1-byte 

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), ignoring any carry, so that offset 
wrap-around loading (from OFFFFFFFFH to OOOOOOOOOH) 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 03AH, the hexadecimal encoding of the ASCII colon 
(':') character. 

RECLEN 
The field contains 03032H, 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 030303030H, the hexadecimal encoding of the ASCII 
characters '0000', since this field is not used for this record. 

RECTYP 
This field contains 03034H, 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 high-order byte is the 
10th/llth character pair of the record.  The low-order byte is the 
12th/13th character pair of the record. 

CHKSUM 
This field contains the check sum on the RECLEN, LOAD OFFSET, RECTYP, 
and ULBA fields. 


4. Extended Segment Address Record (16- or 32-bit formats)

| RECORD  |     LOAD     |         |         |         |         | 
|  MARK   |    RECLEN    | OFFSET  | RECTYP  |  USBA   | CHKSUM  | 
|  ':'    |    '02'      | '0000'  |  '02'   |         |         | 
  1-byte       1-byte      2-bytes   1-byte    2-bytes   1-byte 

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), ignoring any carry, so that offset 
wraparound loading (from OFFFFH to OOOOOH) 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 03AH, the hexadecimal encoding of the ASCII 
colon (':') character. 

RECLEN 
The field contains 03032H, 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 030303030H, the hexadecimal encoding of the 
ASCII characters '0000', since this field is not used for this 
record. 

RECTYP 
This field contains 03032H, 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 high-order byte is the 
10th/1lth character pair of the record.  The low-order byte is the 
12th/13th character pair of the record. 

CHKSUM 
This field contains the check sum on the RECLEN, LOAD OFFSET, 
RECTYP, and USBA fields. 


5. Data Record (8-, 16-, or 32-bit formats)

| RECORD  |     LOAD     |         |         |         |         | 
|  MARK   |    RECLEN    | OFFSET  | RECTYP  |  DATA   | CHKSUM  | 
|  ':'    |              |         |  '00'   |         |         | 
  1-byte       1-byte      2-bytes   1-byte    n-bytes   1-byte 

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 03AH, the hexadecimal encoding of the ASCII 
colon (':') character. 

RECLEN 
The field contains two ASCII hexadecimal digits that specify the 
number of data bytes in the record.  The maximum value is 'FF' or 
04646H (255 decimal). 

LOAD OFFSET 
This field contains four ASCII hexadecimal digits representing the 
offset from the LBA (see Extended Linear Address Record) or SBA (see 
Extended Segment Address Record) defining the address which the 
first byte of the data is to be placed. 

RECTYP 
This field contains 03030H, 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. 

CHKSUM 
This field contains the check sum on the RECLEN, LOAD OFFSET, 
RECTYP, and DATA fields. 


6. Start Linear Address Record (32-bit format only)

| RECORD  |     LOAD     |         |         |         |         | 
|  MARK   |    RECLEN    | OFFSET  | RECTYP  |  EIP    | CHKSUM  | 
|  ':'    |    '04'      | '0000'  |  '05'   |         |         | 
  1-byte       1-byte      2-bytes   1-byte    4-bytes   1-byte 

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 start 
address. 

The contents of the individual fields within the record are: 

RECORD MARK 
This field contains 03AH, the hexadecimal encoding of the ASCII 
colon (':') character. 

RECLEN 
The field contains 03034H, 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 030303030H, the hexadecimal encoding of the 
ASCII characters '0000', since this field is not used for this 
record. 

RECTYP 
This field contains 03035H, 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 high-order byte is the 10th/1lth 
character pair. 

CHKSUM 
This field contains the check sum on the RECLEN, LOAD OFFSET, 
RECTYP, and EIP fields. 


7. Start Segment Address Record (16- or 32-bit formats)

| RECORD  |     LOAD     |         |         |         |         | 
|  MARK   |    RECLEN    | OFFSET  | RECTYP  |  CS/IP  | CHKSUM  | 
|  ':'    |    '04'      | '0000'  |  '03'   |         |         | 
  1-byte       1-byte      2-bytes   1-byte    4-bytes   1-byte 

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 03AH, the hexadecimal encoding of the ASCII 
colon (':') character. 

RECLEN 
The field contains 03034H, the hexadecimal encoding of the ASCII 
characters '04', which is the length, in bytes, of the CS/IP 
register contents within this record. 

LOAD OFFSET 
This field contains 030303030H, the hexadecimal encoding of the 
ASCII characters '0000', since this field is not used for this 
record. 

RECTYP 
This field contains 03033H, the hexadecimal encoding of the ASCII 
character '03', which specifies the record type to be a Start 
Segment Address Record. 

CS/IP 
This field contains eight ASCII hexadecimal digits that specify the 
16-bit CS register and 16-bit IP register contents.  The high-order 
byte of the CS register content is the 10th/llth character pair, the 
low-order byte is the 12th/13th character pair of the record.  The 
high-order byte of the IP register content is the 14th/15th 
character pair, the low-order byte is the 16th/17th character pair 
of the record. 

CHKSUM 
This field contains the check sum on the RECLEN, LOAD OFFSET, 
RECTYP, and CS/IP fields. 


8. End of File Record (8-, 16-, or 32-bit formats)

| RECORD  |     LOAD     |         |         |         | 
|  MARK   |    RECLEN    | OFFSET  | RECTYP  | CHKSUM  | 
|  ':'    |    '00'      | '0000'  |  '01'   |         | 
  1-byte       1-byte      2-bytes   1-byte    1-byte 

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 03AH, the hexadecimal encoding of the ASCII 
colon (':') character. 

RECLEN 
The field contains 03030H, the hexadecimal encoding of the ASCII 
characters '00'.  Since this record does not contain any INFO/DATA 
bytes, the length is zero. 

LOAD  OFFSET 
This field contains 030303030H, the hexadecimal encoding of the 
ASCII characters '0000', since this field is not used for this 
record. 

RECTYP 
This field contains 03031H, the hexadecimal encoding of the ASCII 
character '01', which specifies the record type to be an End of File 
Record. 

CHKSUM 
This field contains the check sum an the RECLEN, LOAD OFFSET, and 
RECTYP fields.  Since all the fields are static, the check sum can 
also be calculated statically, and the value is 04646H, the 
hexadecimal encoding of the ASCII characters 'FF'. 

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