The Records

All records start with an ASCII capital S character, value 0x53, followed by a type specifier byte. All records consist of binary bytes.

The Header Record

Each file starts with a fixed four byte header record.

The Data Records

Each data record consists of 5 fields. These are the type field, length field, address field, data field, and the checksum. The lines always start with a capital S character.

Type

The type field is a one byte field that specifies whether the record has a two‐byte address field (0x31), a three‐byte address field (0x32) or a four‐byte address field (0x33). The address is big‐endian.

Record Length

The record length field is a one byte field that specifies the number of bytes in the record following this byte.

Address

This is a 2‐, 3‐ or 4‐byte address that specifies where the data in the record is to be loaded into memory.

Data

The data field contains the executable code, memory‐loadable data or descriptive information to be transferred.

Checksum

The checksum is a one byte field that represents the least significant byte of the one's complement of the sum of the values represented by the bytes making up the record's length, address, and data fields.

The Termination Record

Each file ends with a fixed two byte termination record.

Size Multiplier

In general, binary data will expand in sized by approximately 1.2 times when represented with this format.