Motorola M68000 User Manual download pdf (Page 352)

MOTOROLA

MC68000 FAMILY PROGRAMMER’S REFERENCE MANUAL

C-1

APPENDIX C

S-RECORD OUTPUT FORMAT

The S-record format for output modules is for encoding programs or data ﬁles in a printable

format for transportation between computer systems. The transportation process can be

visually monitored, and the S-records can be easily edited.

C.1 S-RECORD CONTENT

Visually, S-records are essentially character strings made of several ﬁelds that identify the

record type, record length, memory address, code/data, and checksum. Each byte of binary

data encodes as a two- character hexadecimal number: the ﬁrst character represents the

high- order four bits, and the second character represents the low-order four bits of the byte.

Figure C-1 illustrates the ﬁve ﬁelds that comprise an S-record. Table C-1 lists the composi-

tion of each S- record ﬁeld.

Figure C-1. Five Fields of an S-Record

TYPE RECORD LENGTH ADDRESS CODE/DATA CHECKSUM

Table C-1. Field Composition of an S-Record

Field Printable

Characters

Contents

Type 2 S-record type—S0, S1, etc.

Record Length

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

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.

1 2 ... 347 348 349 350 351 352 353 354 355 356 357

No comments

Motorola M68000 User Manual Page 352