8xp File Structure

Overview

Each 8xp file contains:

• 55 byte header
• 19 byte metadata
• Variable length body
• 2 byte checksum

Header

Signature

• Content: 8 byte signature that is always **TI83F*.
• Encoding: ASCII

Signature Extra

• Content: 2 bytes always with these values: 0x1A, 0x0A.

Mystery Byte

• Content: 1 byte always with the value 0x00.

Comment

• Content: 42 bytes of comment, usually: Created by [Tools Name] [Tools Version]. Padded with 0x00.
• Encoding: ASCII

Metadata and Body Length

The number of bytes in the metadata and body, excluding checksum.

• Content: 2 bytes
• Encoding: little-endian 16-bit integer.

Metadata

Flag

• Content: 1 byte flag, usually 0x0D.

Unknown Byte

• Content: 1 byte always with the value 0x00.

Body and Checksum Length

The number of bytes in the body and checksum.

• Content: 2 bytes
• Encoding: little-endian 16-bit integer.

File Type

• Content: 1 byte
• Encoding:
  • 0x05: Normal Program
  • 0x06: Locked Program
  • 0x17: Groups

Name

• Content: 8 bytes of program name. Padded with 0x00.
• Encoding: ASCII

Version

• Content: 1 byte, usually 0x00.

Is Archived

• Content: 1 byte
• Economics:
  • 0x00: Not archived
  • 0x80: Archived

Body and Checksum Length

The number of bytes in the body and checksum. This is repeated again, for some reason.

• Content: 2 bytes
• Encoding: little-endian 16-bit integer.

Body Length

The number of bytes in the body.

• Content: 2 bytes
• Encoding: little-endian 16-bit integer.

Body

The body of the 8xp file is the actual program data. The length of the body is specified in the metadata.

• Content: Variable length
• Encoding: Check out the 8xp token list

Checksum

• Content: 2 bytes
• Encoding: little-endian 16-bit integer.