Honeywell Information Systems Inc.

Thomas L Murray, Jr

Thomas O Holtey

Gary J Goss

James W Stonier

James C Siwik

Richard P Kelly

Kin C Yu

A data processing system includes a cathode ray tube (CRT) display subsystem and a floppy disk subsystem. The logic of both systems are verified by generating and transferring a fixed format stream of data bits from the CRT display subsystem to the floppy disk subsystem in modified frequency modulation (MFM) mode and checking the information received by the floppy disk subsystem against the original information presented to the CRT display subsystem.

Diskette subsystem fault isolation via video subsystem loopback

A data processing system includes a central processing unit (CPU), an input/output microprocessor, a main memory and a number of mass storage controllers. A block of information is transferred between one of the mass storage controllers and main memory during data multiplex control (DMC) cycles. The CPU includes registers which store the address of main memory into which the next data byte is written or read from and the range indicating the number of data bytes remaining to be transferred. Prior to a DMC cycle the CPU stores address and range information in a mailbox location in an I/O RAM and the I/O microprocessor transfers that information to channel table locations in the I/O RAM. For a DMC operation, the I/O microprocessor transfers the address and range information to the mailbox location and transfers the mass storage information to the mass storage controller. It signals a CPU interrupt and issues a read or write order to the mass storage controller. The CPU then retrieves the address and range information from the mailbox location and initiates a DMC cycle.

Data multiplex control facility

A microprogrammed data processing system includes a central processing unit (CPU), a main memory and a number of mass storage controllers. A block of information is transferred between main memory and one of the mass storage controllers during data multiplex control (DMC) cycles. The main memory stores 2 data bytes in each word location. An input/output RAM stores channel number signals for identifying mass storage controllers. An I/O microprocessor addresses the I/O RAM to read the channel number signals onto the system bus, and a mass storage controller coupled to the system bus responds to the channel number signals to generate a read/write signal. The system responds to a request signal, the read/write signal and a signal indicative of a left or right bit of an addressed location in main memory to generate a plurality of data request signals. A read only memory is addressed in response to the data request signals to read out a plurality of microprograms for processing the data.

Speeding up the response time of the direct multiplex control transfer

The refresh logic of a dynamic MOS memory subsystem of a data processing system is tested by providing apparatus for counting refresh cycles and generating a counter output signal in a first state after a predetermined number of refresh cycles. A microprocessor periodically tests the state of the counter output signal and keeps a count of the number of times the counter output signal was tested and found to be in a second state. When the microprocessor tests and finds the counter output signal in a first state, the microprocessor compares the number of times it tested and found the counter output signal in a second state and determines if that count is within a predetermined range for correct operation.

Apparatus and method for testing and verifying the refresh logic of

A data processing system includes a cathode ray tube (CRT) display subsystem and a floppy disk subsystem. The logic of both systems are verified by generating and transferring a fixed format stream of data bits from the CRT display subsystem to the floppy disk subsystem in modified frequency modulation (MFM) mode and checking the information received by the floppy disk subsystem against the original information presented to the CRT display subsystem. The bit rate of the data stream is varied depending on the number of address locations used in the data RAM of the CRT display subsystem to store each data bit.

Firmware simulation of diskette data via a video signal

A data processing system includes a cathode ray tube (CRT) display. Apparatus associated with the CRT tests and verifies the vertical and horizontal synchronization and the logic associated with a character generator. Refresh signals, horizontal synchronization signals and data bit signals from the character generator are counted. The counts of those signals which occur within a predetermined number of occurrences of vertical synchronization signals are verified.

Apparatus and method for testing and verifying the timing logic of a

In a data processing system having a plurality of units coupled for the transfer of information therebetween over a common electrical bus or for transferring information via a communication channel to other data processing systems during asynchronously generated information bus transfer cycles, an apparatus exists for reformatting data for transfer over the common electrical bus or via the communication channel. The apparatus is comprised of an eight-way multiplexer responsive to control bits for selecting one of eight different formats during write or read operations to or from a memory. Additionally, during read operations, the apparatus transfers a return address from a unit requesting information to the address bus so that data read from memory may be transferred to the requesting device. The formatting control bit is similarly reformatted from the data bus to the address bus bit.

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Merrimack, NH, United States of America

Thomas L Murray, Jr