TI-92 Link Protocol Guide - System Backup Transfers

A System Backup is one large transmission containing all user-modifiable data in the calculator. The file format that the TI-92 Graph Link software uses can be found in the file formats section of this documentation.

System backups must be transferred silently. Silent transfers can only be done between a computer and a calculator, and require that the computer make the request or request-to-send.

Requesting a Backup

The protocol for silently requesting and receiving a backup is described below. For information on packet formats, click here.

Step	Direction			Packet
1				REQ with request-style backup header. Name is "main\backup".
2				ACK
3				VAR with data-style backup header.
4				ACK
5				CTS
6				ACK
7				DATA (a 1-kilobyte backup block, with four extra bytes at the beginning)
8				ACK
				(Repeat steps 3-8 for as many kilobytes as there are in the backup)
9				EOT
10				ACK

The actual backup data is broken into 1-kilobyte blocks which are transferred individually.

Example:

PC:	09 A2 11 00 00 00 00 00 1D 0B 6D 61 69 6E 5C 62 61 63 6B 75 70 9F 04	Request: Backup "main\backup"
TI:	89 56 00 00	Acknowledgement of request
	89 06 0A 00 00 04 00 00 1D 04 31 2E 31 31 E6 00	Variable header: Backup block (rom version "1.11")
PC:	09 56 00 00	Acknowledgement of header
	09 09 00 00	Clear to Send
TI:	89 56 00 00	Acknowledgement of CTS
	89 15 04 04 <404h (1028) bytes of data plus checksum>	First 1-kilobyte block of data (plus four bytes at the beginning)
PC:	09 56 00 00	Acknowledgement of data
TI:	89 06 0A 00 00 04 00 00 1D 04 31 2E 31 31 E6 00	Variable header: Backup block (rom version "1.11")
PC:	09 56 00 00	Acknowledgement of header
	09 09 00 00	Clear to Send
TI:	89 56 00 00	Acknowledgement of CTS
	89 15 04 04 <404h (1028) bytes of data plus checksum>	Second 1-kilobyte block of data (plus four bytes at the beginning)
PC:	09 56 00 00	Acknowledgement of data
. . .	. . .	. . .
TI:	89 06 0A 00 08 02 00 00 1D 04 31 2E 31 31 EC 00	Variable header: Backup block (rom version "1.11")
PC:	09 56 00 00	Acknowledgement of header
	09 09 00 00	Clear to Send
TI:	89 56 00 00	Acknowledgement of CTS
	89 15 0C 02 <20Ch (524) bytes of data plus checksum>	Final block of data (plus four bytes at the beginning)
PC:	09 56 00 00	Acknowledgement of data
TI:	89 92 00 00	End of transmission - no more blocks
PC:	09 56 00 00	Acknowledgement of EOT

Sending a Backup

The protocol for silently sending a backup is shown below:

Step	Direction			Packet
1				VAR with send-style backup header.
2				ACK
3				VAR with data-style backup header.
4				ACK
5				CTS
6				ACK
7				DATA (a 1-kilobyte backup block, without the extra four bytes at the beginning)
8				ACK
				(Repeat steps 3-8 for as many kilobytes as there are in the backup)
9				EOT

Example (PC sending backup to TI):

PC:	09 06 0A 00 08 9A 00 00 1D 04 31 2E 31 31 84 01	Variable header: Backup (rom version "1.11")
TI:	89 56 00 00	Acknowledgement of header
PC:	09 06 0A 00 04 00 00 00 1D 04 31 2E 31 31 E6 00	Variable header: Backup block (rom version "1.11")
TI:	89 56 00 00	Acknowledgement of header
	89 09 00 00	Clear To Send
PC:	09 56 00 00	Acknowledgement of CTS
	09 15 00 04 <400h (1024) bytes of data plus checksum>	First 1-kilobyte block of data
TI:	89 56 00 00	Acknowledgement of data
PC:	09 06 0A 00 04 00 00 00 1D 04 31 2E 31 31 E6 00	Variable header: Backup block (rom version "1.11")
TI:	89 56 00 00	Acknowledgement of header
	89 09 00 00	Clear To Send
PC:	09 56 00 00	Acknowledgement of CTS
	09 15 00 04 <400h (1024) bytes of data plus checksum>	Second 1-kilobyte block of data
TI:	89 56 00 00	Acknowledgement of data
. . .	. . .	. . .
PC:	09 06 0A 00 08 02 00 00 1D 04 31 2E 31 31 EC 00	Variable header: Backup block (rom version "1.11")
TI:	89 56 00 00	Acknowledgement of header
	89 09 00 00	Clear To Send
PC:	09 56 00 00	Acknowledgement of CTS
	09 15 08 02 <208h (520) bytes of data plus checksum>	Final block of data
TI:	89 56 00 00	Acknowledgement of data
PC:	09 92 00 00	End of transmission

Silent transfers

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