Motorola M68HC11EVB, Руководство пользователя

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S-RECORD INFORMATION
M68HC11EVB/D A-1
1
APPENDIX A
S-RECORD INFORMATION
A.1 INTRODUCTION
The S-record format for output modules was devised for the purpose of encoding programs or
data files in a printable format for transportation between computer systems. The transportation
process can thus be visually monitored and the S-records can be more easily edited.
A.2 S-RECORD CONTENT
When viewed by the user, S-records are essentially character strings made of several fields which
identify the record type, record length, memory address, code/data, and checksum. Each byte of
binary data is encoded as a 2-character hexadecimal number: the first character representing the
high-order 4 bits, and the second the low-order 4 bits of the byte.
The 5 fields which comprise an S-record are shown below:
TYPE RECORD LENGTH
ADDRESS
CODE/DATA
CHECKSUM
where the fields are composed as follows:
Field
Printable
Characters Contents
Type 2 S-record type - S0, S1, etc.
Record length 2 The count of the character pairs in the record, excluding the type and
record length.
Address 4, 6, or 8 The 2-, 3-, or 4-byte address at which the data field is to be loaded into
memory.
Code/data 0-2n From 0 to n bytes of executable code, memory loadable data, or
descriptive information. For compatibility with teletypewriters, some
programs may limit the number of bytes to as few as 28 (56 printable
characters in the S-record).
Checksum 2 The least significant byte of the one's complement of the sum of the
values represented by the pairs of characters making up the record
length, address, and the code/data fields.