AM3270/TR3271 Reference Manual

Contents
vi 086705 Tandem Computers Incorporated
Using Multiple-Level Access Methods 3-6
Level 1—Bisync Driver 3-7
Level 2—Multipoint Supervision 3-7
Level 3—Request Processor 3-10
Level 4—Subdevice Protocols 3-10
Error Handling 3-11
Section 4 AM3270 Subdevice Protocols
What Are They? 4-1
Details of the ITI Protocol 4-1
Message Formats 4-1
Subdevice Information 4-2
Applicable File-System Procedures 4-2
CONTROL 11 and 12 (Modem Connect or Disconnect) 4-3
READ Request 4-3
SETMODE Functions 4-3
SETPARAM 3 (BREAK Indication) 4-4
WRITE Request 4-6
WRITEREAD Request 4-6
Error Handling 4-6
Details of the PTP Protocol 4-7
Joining Subdevices 4-8
Data Transfer 4-8
Formatting 4-8
Loss of Communication 4-9
Error Handling 4-9
Details of the CRT Protocol 4-9
Message Format—Outbound Data 4-10
Message Format—Inbound Data 4-10
Applicable File-System Procedures 4-11
CONTROL 22 (Two-Step READ Operation) 4-11
READ Request 4-13
SETMODE 53 Operation 4-13
SETMODE 54 Operation 4-15
SETMODE 59 Operation 4-16
WRITE Request 4-16
Error Handling 4-17