Motorola M68CPU32BUG, Руководство пользователя

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S-RECORD INFORMATION
M68CPU32BUG REV 1 A-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 five 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-records type -- S0, S1, etc.
record length 2 The count of the character pairs in the record, excluding 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-n 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 records
length, address, and the code/data fields.