Abstract:
A specialized circuit set is included in a data processing system wherein the circuit set registers can be configured into a serial array. A clock signal distribution system delivers controlled clock signals to selected serial arrays. A maintenance data processor provides predetermined signal groups and addressing apparatus responsive to the predetermined signal groups loads and unloads register arrays in response to the predetermined signals. A predetermined signal group is entered into the serial register array, a predetermined number of clock cycles are applied, and the resulting signals shifted from the serial register array are applied to the maintenance data processor for display or analysis. By comparing the expected result for a given initial state with the actual result of an operation sequence, the accuracy of the operation of the data processing system, or any portion thereof, is thereby determined.
Abstract:
In an input/output multiplexer of a data processing unit, a plurality of components, capable of independent activity, provide for the simultaneous execution of a multiplicity of operations involving the exchange of signal groups between a central subsystem and peripheral subsystems. The input/output multiplexer includes apparatus for controlling the receipt from delivery to the central subsystem and peripheral subsystems of signal groups. Apparatus is provided to execute address development normally performed in the central subsystem. Apparatus is also provided to analyze control subsystem signal groups and generate pre-selected command signal groups for delivery to the central subsystem or to the peripheral subsystems. Apparatus in the input/output multiplexer also provides a status of each operation currently in execution.
Abstract:
An apparatus for decoding and synchronizing data wherein only logic ZERO data bits are received as electronic pulses, each pulse alternating in opposite directions and wherein logic ONE data bits are received as no pulse. The synchronization logic includes a counter which is delayed a count of binary ONE if the logic ZERO data bit is received late, and the counter is advanced a count of binary ONE if the logic ZERO data bit is received early.
Abstract:
A track of a disk device is formatted on a single revolution of the disk by using a read only memory (ROM) to store control codes and a random access memory (RAM) to store address field and data field bytes. A DMA controller simultaneously addresses ROM and RAM. Control codes are read into a control first in-first out memory and data codes are read into a data first in-first out memory. The control codes are applied to a decoder whose output signals control cyclic redundancy check and error detection and correction logic as well as the data first in-first out memory. The serial output from both the data first in-first out memory and the cyclic redundancy check logic are written on disk track.
Abstract:
An apparatus for varying the pulse width of a computer clock by adding a predetermined amount of time to the clock pulse width. A synchronous counter is combined with a latch into a circuit whereby a pulse input to the circuit resets both the latch and counter on the leading edge, and whereby the trailing edge of the input pulse releases the latch and counter allowing the counter to count clock pulses. On a predetermined pulse the counter's carry-output terminal clocks a logic high into the D latch terminal. Concurrently, an output from the latch is fed back to the counter's count-enable input to disable counting until a subsequent pulse resets the circuit. The net effect is to add a predetermined amount of time to the input pulse so that the extended pulse is available at the output of the latch.
Abstract:
An apparatus for encoding data for serial transmission wherein only logic ZEROs are transmitted as electronic pulses, each pulse alternating in opposite direction and wherein logic ONEs require no pulse.
Abstract:
An interactive computer terminal system having a bus for communication between elements of the system is disclosed having apparatus for assigning control of the computer bus on a predetermined order of priority. The CPU receives requests from computer system elements and assigns time slots for use of the system bus by arbitrating among various resources competing for access to the bus.
Abstract:
A diskette read data recovery system generates a clock which is locked to an incoming data stream. In a phase locked loop, a signal generated by an oscillator and frequency dividers is compared in phase to the incoming data stream to provide first or second signals depending on whether the incoming data signal leads or lags the clock signal. In order that the system may handle different types of incoming signals, different frequency divider circuits in the phase locked loop are selected for different incoming signals.
Abstract:
Apparatus and method for a supervisor for data processing system capable of utilizing a plurality of operating systems. The supervisor includes apparatus for identifying a condition in the data processing system requiring a different operating system. A reserved memory area associated with the currently active operating system is then addressed and register contents of a central processing unit are stored in the reserved memory area. The reserved memory of the operating system being activated is addressed and causes the address of the reserved memory of the operating system being activated, the data related to permitting the physical memory associated with the operating system being activated, contents of registers safestored in the reserve-memory and, data establishing the decor of the operating system being activated are entered in the central processing unit. The operating system to be activated is then enabled, and execution of permitted instructions by the second operating system is begun. The physical memory locations are determined by a real address through use of a paging mechanism permitting storage of portions of the operating systems in non-contiguous groups of locations while isolating the memory available to each operating system.