S-Record Format
    
    A file in Motorola S-record format is an ASCII file. There are three different 
    formats:

        S19     for 16-bit address 
        S2      for 24-bit address
        S3      for 32-bit address

    
    The files consist of optional symbol table information, data specifications 
    for loading memory, and a terminator record.

        [ $$ {module_record}
        symbol records
        $$ [ module_record ]
        symbol_records
        $$]
        header_record
        data_records
        record_count_record
        terminator_record


Module Record (Optional)

    Each object file contains one record for each module that is a component of it. This
    record contains the name of the module. There is one module record for each relocatable 
    object created by the assembler. The name of the relocatable object module
    contained in the record comes from the IDNT directive. For absolute objects created
    by the linker, there is one module record for each relocatable object file linked,
    plus an additional record whose name comes from the NAME command for the
    linker.

    Example:

        $$ MODNAME


Symbol Record (Optional)

    As many symbol records as needed can be contained in the object module. Up to 4
    symbols per line can be used, but it is not mandatory that each line contain 4 
    symbols. A module can contain only symbol records.

    Example:

        APPLE $00000 LABEL1 $ODOC3
        MEM $OFFFF ZEEK $01947

    The module name associated with the symbols can be specified in the
    module_record preceding the symbol records.

    Example:

        $$MAIN

    Symbols are assumed to be in the module named in the preceding module_record
    until another module is specified with another module_record. Symbols defined by
    the linker's PUBLIC command appear following the first module record, which
    indicates the name of the output object module specified by the linker's NAME
    command.


*****************************************************************************************

Header Record (SO)

    Each object module has exactly one header record with the following format:

        S00600004844521B

    Description:

        S0         Identifies the record as a header record
        06         The number of bytes following this one
        0000       The address field, which is ignored
        484452     The string HDR in ASCII
        1B         The checksum



*****************************************************************************************

Data Record (S1)

    A data record specifies data bytes that are to be loaded into memory. Figure 1
    shows the format for such a record. The columns shown in the figure represent half
    of a byte (4 bits).

                ---------------------------------------------
                |  1 2  3 4   5 6 7 8   9 ... 40    41 42   |
                |                                           |
                |  S ID byte   load    data...data checksum |
                |       count address   1      n            |
                ---------------------------------------------
            Figure 1: Data Record Formatter 16-Bit Load Address


        Column      Description

        1           Contains the ASCII character S, which indicates the start of
                    a record in Motorola S-record format.

        2           Contains the ASCII character identifying the record type.
                    For data records, this character is 1.

        3 to 4      Contain the count of the number of bytes following this one
                    within the record. The count includes the checksum and the
                    load address bytes but not the byte count itself.

        5 to 8      Contain the load address. The first data byte is to be loaded
                    into this address and subsequent bytes into the next sequential
                    address. Columns 5 and 6 contain the high-order address
                    byte, and columns 7 and 8 contain the low-order address byte.

        9 to 40     Contain the specifications for up to 16 bytes of data.

        41 to 42    Contain a checksum for the record. To calculate this, take the
                    sum of the values of all bytes from the byte count up to the
                    last data byte, inclusive, modulo 256. Subtract this result
                    from 255.


*****************************************************************************************

Data Record (S2)


    A data record specifies data bytes that are to be loaded into memory. Figure 2
    shows the format for such a record. The columns shown in the figure represent half
    of a byte (4 bits).


                ----------------------------------------------------
                |  1 2   3 4   5 6 7 8 9 10   11 ...  42   43 44   |
                |                                                  |
                |  S ID  byte     load        data...data checksum |
                |        count   address       1      n            |
                ----------------------------------------------------
                Figure 2: Data Record Format for 24-Bit Load Address

        Column      Description

        1           Contains the ASCII character S, which indicates the start of
                    a record in Motorola S-record format.

        2           Contains the ASCII character identifying the record type.
                    For data records, this character is 2.

        3 to 4      Contain the count of the number of bytes following this one
                    within the record. The count includes the checksum and the
                    load address bytes but not the byte count itself.

        5 to 10     Contain the load address. The first data byte is to be loaded
                    into this address and subsequent bytes into the next sequential 
                    address. Columns 5 and 6 contain the high-order address
                    byte, and columns 9 and 10 contain the low-order address byte.

        11 to 42    Contain the specifications for up to 16 bytes of data.

        43 to 44    Contain a checksum for the record. To calculate this, take the
                    sum of the values of all bytes from the byte count up to the
                    last data byte, inclusive, modulo 256. Subtract this result
                    from 255.


*****************************************************************************************

Data Record (S3)


    A data record specifies data bytes that are to be loaded into memory. Figure 3
    shows the format for such a record. The columns shown in the figure represent half
    of a byte (4 bits).

                ----------------------------------------------------------
                |  1 2   3 4   5 6 7 8 9 10 11 12   13 ... 44    45 46   |
                |                                                        |
                |  S ID  byte        load          data...data  checksum |
                |        count      address         1      n             |
                ----------------------------------------------------------
                Figure 3: Data Record Format for 32-Bit Load Address

    Column          Description

    1               Contains the ASCII character S, which indicates the start of
                    a record in Motorola S-record format.

    2               Contains the ASCII character identifying the record type.
                    For data records, this digit is 3 for 32-bit addresses.

    3 to 4          Contain the count of the number of bytes following this one
                    within the record. The count includes the checksum and the
                    load address bytes but not the byte count itself.

    5 to 12         Contain the load address. The first data byte is to be loaded
                    into this address and subsequent bytes into the next sequential 
                    address. Columns 5 and 6 contain the high-order address
                    byte, and columns 11 and 12 contain the low-order address byte.

    13 to 44        Contain the specifications for up to 15 bytes of data.

    45 to 46        Contain a checksum for the record. To calculate this, take the
                    sum of the values of all bytes from the byte count up to the
                    last data byte, inclusive, modulo 256. Subtract this result
                    from 255.


*****************************************************************************************

Record Count Record (S5)


    The record count record verifies the number of data records preceding it. Figure 4
    shows the format for such a record. The columns shown in the figure represent half
    of a byte (4 bits).

                --------------------------------------
                |  1 2   3 4      5 6 7 8     9 10   |
                |                                    |
                |  S ID  byte    # of data  checksum |
                |        count    records            |
                --------------------------------------
                Figure 4: Record Count Record Format

    Column          Description

    1               Contains the ASCII character S, which indicates the start of
                    a record in Motorola S-record format.

    2               Contains the ASCII character 5, which indicates a record
                    count record.

    3 to 4          Contain the byte count, ASCII string 03.

    5 to 8          Contain the number of data records in this file. The high-
                    order byte is in columns 5 and 6.

    9 to 10         Contain the checksum for the record.

    Example:

        S503010DEE

    The example above shows a record count record indicating a total of 269 records
    (0x010D) and a checksum of 0xEE.



*****************************************************************************************

Terminator Record for 32-bit address (S7)

    A terminator record specifies the end of the data records. Figure 5 shows the
    format for such a record. The columns shown in the figure represent half of a byte
    (4 bits).

                -------------------------------------
                |  1 2   3 4      5...12    13 14   |
                |                                   |
                |  S ID  byte     load     checksum |
                |        count   address            |
                -------------------------------------
                Figure5: Terminator Record Format for 32-Bit Load Address

    Column          Description

    1               Contains the ASCII character S, which indicates the start of
                    a record in Motorola S-record format.

    2               Contains the ASCII character 7, which indicates a 32-bit
                    load address.

    3 to 4          Contain the byte count, ASCII string 04.

    5 to 12         Contain the load address that is either set to zero or to the
                    starting address specified in the END directive or START
                    command (there are no data bytes).

    13 to 14        Contain the checksum for the record.

*****************************************************************************************

Terminator Record for 24-bit address (S8)


    A terminator record specifies the end of the data records. Figure 6 shows the
    format for such a record. The columns shown in the figure represent half of a byte
    (4 bits).

                ----------------------------------------
                |  1 2   3 4    5 6 7 8 9 10   11 12   |
                |                                      |
                |  S ID  byte       load      checksum |
                |        count     address             |
                ----------------------------------------
                Figure 6: Terminator Record Format for 24-Bit Load Address

    Column          Description

    1               Contains the ASCII character S, which indicates the start of
                    a record in Motorola S-record format.

    2               Contains the ASCII character 8, which indicates a 24-bit
                    load address.

    3 to 4          Contain the byte count, ASCII string 04.

    5 to 10         Contain the load address, which is either set to zero or to the
                    starting address specified in the END directive or START
                    command. There are no data bytes.

    11 to 12        Contain the checksum for the record.

    Example:

        S804000AF0001

    The previous example shows a terminator record with a 24-bit load address of
    0x000AF0 and a checksum of 0x01.


*****************************************************************************************

Terminator Record for 16-bit address (S9)


    A terminator record specifies the end of the data records. Figure 7 shows the
    format for such a record. The columns shown in the figure represent half of a byte
    (4 bits).

                -------------------------------------
                |  1 2   3 4    5 6 7 8      9 10   |
                |                                   |
                |  S ID  byte    load      checksum |
                |        count  address             |
                -------------------------------------
                Figure 7: Terminator Record Format for 16-Bit Load Address


    Column         Description

    1               Contains the ASCII character S, which indicates the start of
                    a record in Motorola S-record format.

    2               Contains the ASCII character 9, which indicates a 16-bit
                    load address.

    3 to 4          Contain the byte count, ASCII string 04.

    5 to 8          Contain the load address, which is either set to zero or to the
                    starting address specified in the END directive or START
                    command (there are no data bytes).

    9 to 10         Contain the checksum for the record.



*****************************************************************************************
 Heiko Hagedorn   h.hag@gmx.de
