Packet format for the CASIOLINK protocol

All packets in the CASIOLINK protocol are introduced by a single byte, which defines the basic purpose of the packet, and defines the kind of payload that follows it.

Value	Name	Description	Payload
0x06	ACKNOWLEDGE	The receiver accepts the data packet, confirms overwrite, or the sender confirms overwrite.	(none)
0x13	ESTABLISHED	The receiver acknowledges connection establishment.	(none)
0x15	ABORT	The sender requests an interactive connection, or aborts overwrite if an overwrite confirmation is requested.	(none)
0x16	START	The sender requests a non-interactive connection.	(none)
0x21 (!)	ALREADY_EXISTS	The receiver requests overwrite confirmation from the sender.	(none)
0x24 ($)	INVALID_DATA	The receiver rejects the data packet due to an invalid data type, or because it is out of memory.	(none)
0x2B (+)	CORRUPTED	The received rejects the packet due to an invalid checksum. The transfer aborts.	(none)
0x3A (:)	HEADER	Header payload.	One of: CAS40 header format CAS50 header format CAS100 header format Arbitrary data in the context of previously sent headers, for the CAS40 and CAS50 protocol variants.
0x3E (>)	DATA	Data payload.	Packet containing data related to a previously accepted header with the CAS100 variant of the protocol.
0x51 (Q)	INVALID_DATA	The receiver aborts the transfer due to errors in the header.	(none)

CAS40 header format

This data payload uses the same format as CASIOLINK CAS40 main memory files; see CAS40 main memory file format for more information.

CAS50 header format

This data payload uses the same format as CASIOLINK CAS50 main memory files; see CAS50 main memory file format for more information.

CAS100 header format

This header format covers headers used with the AlgebraFX / Graph 100. Such headers are 39-bytes long (excluding the basic purpose byte), but transferred at higher speeds.

The format of such headers is the following:

Offset	Size	Field name	Description	Values
0 (0x00)	4 B	Type (T)	Basic content of the packet	MDL1
4 (0x04)	34 B	Type-specific data	Data for which the format is specific to the type.	See the type description for the format of this component. If the type-specific data is less than 34 bytes, the rest is filled with \xFF.
38 (0x26)	1 B	Checksum (CS)	Checksum for the packet.

ADN1 headers

These packets seem to be used to send data.

Offset	Size	Field name	Description	Values
0 (0x00)	4 B	Data Type (DT)		INF1 (System), FR00 (Segment), MSG1 (Language)
4 (0x04)	4 B	?		Integer (little endian), e.g. 0x40000 (256 * 1024)
8 (0x08)	4 B	?		Integer (little endian), e.g. 0x80000000
12 (0x0C)	4 B	?		Integer (little endian), e.g. 0x200 (512).

ADN2 headers

Unknown purpose.

Offset	Size	Field name	Description	Values
0 (0x00)	4 B	Data Type (DT)		INF1 (System), FR00 (Segment), MSG1 (Language)
4 (0x04)	4 B	?		Integer (little endian), e.g. 0x00000000 (0).
8 (0x08)	4 B	?		Integer (little endian), e.g. 0x100 (256).

BKU1 headers

Unknown purpose.

Offset	Size	Field name	Description	Values
0 (0x00)	4 B	Data Type (DT)		RAMS, RAMI, RAM1
4 (0x04)	4 B	?		Big endian 32-bit integer, e.g. 0xE000.

END1 headers

These packets are sent at the end of the communication.

They do not use additional data.

FCL1 headers

Unknown purpose.

Offset	Size	Field name	Description	Values
0 (0x00)	4 B	Data Type (DT)		S000

FMV1 headers

Unknown purpose.

Offset	Size	Field name	Description	Values
0 (0x00)	4 B	Data Type (DT)		FR00
4 (0x04)	8 B	Data Type 2 (DT2)		FR00 (sic.)

MCS1 headers

These packets contain main memory data.

Offset	Size	Field name	Description	Values
0 (0x00)	3 B	Reserved		Set to \0.
3 (0x03)	2 B	File size		Big-endian 16-bit integer (?).
5 (0x05)	1 B	Data type		8-bit integer, among the following: Data type Description 0x01 Program
6 (0x06)	8 B	Data name		0xFF optionally terminated string.
14 (0x0E)	8 B	Group name		0xFF optionally terminated string.

MDL1 headers

These packets contain initialization data for the CAS100 variant of the CASIOLINK protocol, with calculator model information.

Offset	Size	Field name	Description	Values
0 (0x00)	6 B	Model Identification (M)		ZX945\0
6 (0x06)	6 B	Baud speed (BS)	?	ASCII-DEC, e.g. 038400
12 (0x0C)	1 B	Parity (PAR)	?	N, E or O
13 (0x0D)	4 B	OS Version (VER)		1.00
17 (0x11)	4 B	Flash ROM capacity		Little endian 32-bit integer, e.g. 0x100000 (1048576, 1 MiB).
21 (0x15)	4 B	RAM capacity		Little endian 32-bit integer, e.g. 0x40000 (262144, 256 KiB).
25 (0x19)	4 B	Unknown		Little endian 32-bit integer, e.g. 0x10000 (65536, 64 KiB).
29 (0x1D)	4 B	Unknown		4-char string, e.g. "0x07" (0x30, 0x78, 0x30, 0x37).

REQ1 headers

These packets seem to be used to request information.

Offset	Size	Field name	Description	Values
0 (0x00)	4 B	Data Type (DT)		INF1 (System), FR00 (Segment), MSG1 (Language)

REQ2 headers

Unknown purpose.

Offset	Size	Field name	Description	Values
0 (0x00)	4 B	Data Type (DT)		INF1 (System), FR00-FR09 (Segment), MSG1 (Language), MR04 (?)
4 (0x04)	4 B	?		Integer (little endian), e.g. 0.
8 (0x08)	4 B	?		Integer (little endian), e.g. 0x20000000 (512 * 1024 * 1024)

SET1 headers

Unknown purpose.

Offset	Size	Field name	Description	Values
0 (0x00)	2 B	?		\x30\x01
2 (0x02)	8 B	?		0xFF optionally terminated string, e.g. Y=Data.