Appendix A S-Record Information; A-1. Introduction; A-2 S-Record Content - Motorola M68HC11EVBU User Manual

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
where the fields are composed as follows:
Field Printable
Characters
Type 2
Record length 2
Address 4, 6, or 8
Code/data 0-2n
Checksum 2
M68HC11EVBU/D
APPENDIX A
S-RECORD INFORMATION
ADDRESS
S-record type – S0, S1, etc.
The count of the character pairs in the record, excluding the type and
record length.
The 2-, 3-, or 4-byte address at which the data field is to be loaded into
memory.
From 0 to n bytes of executable code, memory load-able 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).
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.
S-RECORD INFORMATION
CODE/DATA CHECKSUM
Contents
A-1