X3T9.2 92-033 rev 0 To: John Lohmeyer, chairman of X3T9.2 From: Scott Smyers, Apple Computer, Inc. Subject: Proposal for implementation requirements for SCSI3 devices which use the 1394 physical interface Date: February 7, 1992 The 1394 physical interface enables a new class of products which did not previously exist. For example, devices which today must have massive buffers, such as laser printers, could be implemented with substantially smaller buffering if there existed a deterministic data delivery mechanism whereby the rate of data delivery could be matched precisely to the data delivery requirement. The 1394 physical medium provides such a mechanism. However, in order to exploit this and other intrinsic features of 1394, implementors of low cost products, such as laser printers, must be able to assume a baseline feature set. Therefore, the baseline feature set listed below will be required of all devices described in the SCSI document which could serve as data storage devices and which implement the 1394 physical interface. The second list of implementation requirements is a necessary set for all 1394 devices in general. Note: The lists below are not complete and are subject to substantial revision! Required of all 1394 devices which could be used for mass storage in a system environment (e.g., rotating media storage devices, and others): 1) Must implement a minimum of 1 isochronous channel capable of continuous data transfer at a minimum fixed rate of 1.536Mbps while concurrently acting on unrelated asynchronous commands. 2) Must support asynchronous command time-out. 3) Must support a logical block size of 1 byte. Optionally, other logical block sizes may also be supported. 4) Must support spindle synchronization to the 1394 cycle start packet. Must be able to run in spindle synch and non- spindle synch operation. 5) Must have a minimum of 2 ports. 6) Must meet all minimal SCSI requirements (i.e., mandatory commands, etc., as per the appropriate SCSI3 standards documents). Required of all 1394 devices: 1) Minimal set of 1212 unit ROM entries (to be defined, but will be a small well defined set). In addition to this list of requirements, there is also a need to standardize connectors for carrying signals and power between a disk drive and the connection point to outside the box. Either the SCSI committee or the Small Form Factor committee may do well to consider proposals for connectors on the drive to the external connection point in the 1394 environment.