International Business Machines Corporation

Gregory J Moore

Don S Keener

Arthur L Chin

Eric S Stine

Timothy V Lee

Serafin J Garcia, Jr

Richard W Voorhees

Stephanie P Payne

Serafin J Eleazar-Garcia, Jr

A computing system with a SCSI controller includes SCSI transmission mode selection apparatus and method to switch the transmission line drivers between transmitting in SCSI 1, SCSI 2 or another mode. The controller selects a maximum data transmission rate compatible with each peripheral device connected to the controller. A user-defined option code is decoded by the controller to provide the user with control over transmission mode options for the drivers in the controller. Based on the data transmission rate and the selected option, the controller selects the SCSI transmission mode to use for each driver type, acknowledge line or data lines.

System providing user definable selection of different data transmission

This invention relates to personal computers, and more particularly to a personal computer using a small computer systems interface (SCSI) controller coupled directly to the local processor bus for controlling data transfer with storage memory devices such as fixed or removable media electromagnetic storage devices. The storage controller in accordance with this invention has internal volatile memory for transitory storage of data being communicated to coupled volatile memory. It further has control drivers interposed between the internal volatile memory and external volatile memory for controlling communication of data to the external volatile memory, with an enable driver and an enable receiver enchained between the control drivers and a source of signals controlling data communication. The enchained driver and receiver are connected for issuing a write signal to the external volatile memory prior to enablement of data communication through the control drivers and for sustaining a control signal communicated to the control drivers for enabling data communication until after deactivation of the write signal.

Personal computer system having storage controller with memory write

This invention relates to personal computers, and more particularly to a personal computer using a small computer systems interface (SCSI) controller coupled directly to the local processor bus for controlling data transfer with storage memory devices such as fixed or removable media electromagnetic storage devices. The personal computer system has a high speed local processor data bus, at least one logical processor device coupled directly to the local processor bus and capable of signalling through the local processor bus an occurrence of the transfer of blocks of data, and a storage controller coupled directly to the local processor bus for regulating communications between the processor device and storage memory devices. The storage controller has a FIFO memory for transitory storage of blocks of data being exchanged with the local processor bus and is capable of signalling through the local processor bus the state of the FIFO memory. The processor device and storage controller cooperate for exchange of blocks of data between the local processor bus and FIFO memory when the FIFO memory has available one of data to be transferred and space for reception of data and for emptying of the FIFO memory through the local processor bus as necessary.

Personal computer system having high speed local processor bus and

A digital bus circuit having an Address/Data port select decoder 170 in circuit communication with a Selector 194, a Data Port Buffer/Register 181, and an Address Port register 208. The Selector 194 is in circuit communication with an auto incrementor 216, an auto decrementor 218, and a polling function. The incrementor 216 serves to automatically increment an address present in the Address port register 208. The decrementor 218 serves to automatically decrement an address present in the Address port register 208. The polling function serves to reload the Address port register 208 with the same address. The present invention allows a number of enhanced programming methods which permit input and output operations to be implemented with fewer program code instructions. One of the programming methods disclosed by the present invention is an enhanced method of 'polling' a device's internal register by accessing the polling function.

Digital I/O bus controller circuit with auto-incrementing,

This invention relates to personal computers, and more particularly to a personal computer using a small computer systems interface (SCSI) controller for controlling data transfer with storage memory devices such as fixed or removable media electromagnetic storage devices. The personal computer has three interface circuits and a controller processor. The interface circuits control exchange of data among the system central processing unit (CPU), a controller processor, and one or more storage device(s) connected to a SCSI bus. One of the interface circuits includes a least one register for storing data indicative of the content and status of a plurality of sequences of commands ('threads') issued or to be issued to the SCSI device(s).

Personal computer with small computer system interface (SCSI) data flow

This invention relates to personal computers, and more particularly to a personal computer using a FIFO registers for data transfer as illustrated by a bus master device in the form of a small computer systems interface (SCSI) controller for controlling data transfer with storage memory devices such as fixed or removable media electromagnetic storage devices. In the practice of this invention, the efficiency of a system having a plurality of bus master devices is enhanced by providing for a programmable threshold fill condition for a FIFO register before arbitration for bus control occurs. Thus the invention provides an approach to maximizing the efficiency of data transfer where FIFO registers are used.

Personal computer with programmable threshold FIFO registers for data

This invention relates to personal computers, and more particularly to a personal computer using a small computer systems interface (SCSI) controller coupled directly to the local processor bus for controlling data transfer with storage memory devices such as fixed or removable media electromagnetic storage devices. The personal computer has a high speed local processor data bus and a storage controller coupled directly to said local processor bus for regulating communications between a processor and storage memory devices. The storage controller has at least one counter for tracking at least one of address and count data for blocks of data being transferred and capable of signalling through the local processor bus the state of the counter, and a bi-stable device interposed between the counter and the local processor bus for enabling delivery to the local processor bus of data representing an initial state of the counter at the beginning of a transfer of blocks of data and for continuing delivery of initial state data throughout a transfer of blocks of data. The counter and bi-stable device cooperate for permitting one of incrementing and decrementing of the counter during transfer of blocks of data while avoiding changes in counter state data delivered to the local processor bus during transfer of blocks of data.

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Boca Raton, FL, United States of America

Gregory J Moore