Method for controlling the expansion of connections to a SCSI bus

DETAILED DESCRIPTION : It is an object of the present invention to provide a method to control connectivity circuitry that is an improvement over and above the standard SCSI connectivity.
It is another object of this invention to provide program control of circuitry that allows an increase in the number of Storage Data Modules for each host adapter from one to seven for an 8-bit host adapter, or to 15 for 16-bit host adapters.
It is yet another object of this invention is to provide a method that will allow four host adapters to address dual ported drives in a single Storage Data Module.
A still further object of this invention is to provide a method that allows a single host adapter to address up to forty-nine 8-bit devices or one hundred and five 16-bit devices.
The present invention is useful in a data processing system having a data processor coupled to a SCSI channel disposed for transmitting and receiving data between the data processor and a peripheral storage subsystem.
The present invention is a method for controlling a bridge controller that permits expanding the maximum allowable number of disk drives connectable to the SCSI channel.
The method comprises the steps of receiving a command from the SCSI channel; initializing queue pointers from a memory in response to the command; determining the command type and setting flags and pointers in response thereto; when the command is a write operation, transferring data from the SCSI channel and storing the data in the memory; selecting a disk drive to receive the data by sending message and command bytes to the disk drive; and, transferring the data from the memory to the selected disk drive.
These and other objects, advantages, aspects and features of the present invention will be more fully understood and appreciated upon consideration of the following detailed description of one embodiment, presented in conjunction with the accompanying drawings.