Honeywell Information Systems Italia

Honeywell Information Systems Inc.

Bull Hn Information Systems, Inc.

Bull Hn Information Systems Italia S.p.a.

Honeywell Information System Italia

Tiziano Maccianti

Vittorio Zanchi

Luciano Raimondi

Angelo Oldani

Flavio Balasini

A local memory fast selection apparatus is utilized in a data processing system having a plurality of memory resources including a local memory and addressing by logical/virtual addresses which are converted into physical addresses. The local memory fast selection apparatus comprises a memory management unit (MMU) for converting a logical address in a physical address and for generating a destination code which identifies the memory resource, and an auxiliary memory having the same number of addressable locations of the MMU and loaded together with the MMU. The auxiliary memory has a physical address corresponding to the logical address by which the MMU is addressed and a destination code. The auxiliary memory stores a bit decoded from the destination code and selects a predetermined memory resource. Thus, the auxiliary memory and the MMU can be read out together with the same logical address in order to jointly obtain a physical address from the MMU and a selection signal of the predetermined memory resource from the auxiliary memory without any delay caused by decoding operations.

Local memory fast selecting apparatus including a memory management unit

A fault tolerant computer architecture in which a functional unit is duplicated and the input and output signals to and from the two units are compared with each other by comparators to provide an error signal in case of different behavior of the two units, resulting in different input/output signals. The operation of both functional units is controlled by a first read only control memory or alternatively by a second read/write control memory once it has been loaded with microprograms, under control of the first read only control memory. The correct behavior of the comparators is tested in a diagnostic mode by having one functional unit operated under control of the first memory and the other functional unit operated under control of the second memory, so that the two units are controlled to perform different functions which force the comparators to produce an error indication, the absence of which indicates that the comparators operation is faulty.

Fault tolerant computer architecture

Computer control memory apparatus is disclosed wherein the microinstructions may selectively have a variable bit length. A main control memory stores microinstructions having a basic length and they are read out and stored in a microinstruction register. Microinstruction prefixes are obtained from more than one source and are selectively added to the basic length microinstruction in the microinstruction register to create longer microinstructions, as needed, for controlling the operation of the computer. The microinstruction prefixes may be obtained from a secondary control memory that is addressed at the same time as the main control memory, or may be obtained from a field of N bits which is a part of a previous microinstruction read out of the main control memory and saved in an expansion register, or may be all zeroes when it is not desired to expand a microinstruction of basic length read out of the main control memory. All such microinstruction prefixes are connected via a multiplexer from their source to the portion of the microinstruction register used for prefixing them to the basic length microinstructions. In the event an interrupt occurs to obtain a higher priority string of microinstructions, the multiplexer is prevented from connecting the sources of microinstruction prefixes to the microinstruction register until the interrupt is ended.

Computer control memory apparatus providing variable microinstruction

Sequencer means for a microprogrammed control unit which develops consecutive addresses of microprograms, branches to subroutines with address saving and possible return to microprogram, as well as interrupting microprogram forcings with address saving of the interrupted microprograms. In order to allow the double saving of microprogram and subroutine addresses in case of concurrent interruptions and branches, the sequencer means is provided with two address generation loops each including a register. The two loops have a common portion to which they accede through a multiplexer. The first loop is further coupled to a saving register stack. While the first loop executes the saving of a microprogram address and the latching or a branch address received from the second loop, the second loop executes a first updating and related latching or interrupting microprogram address. During the following cycle, by command of the first microinstruction of the interrupting microprogram, the second loop performs a first updating and related latch of the interrupting microprogram address and the first loop saves into the register stack the branch address and performs a second updating and related latching of the interrupting microprogram address.

Sequencer means for microprogrammed control unit

A system comprising interface circuits for coupling together for bidirectional information communication the various units of a data processing system, wherein such communication is effected by a totally interlocked bidirectional dialogue carried out over a single lead, but utilizing signals transmitted on another lead of the interface for clearing the interface circuits associated with the single lead.

System for bidirectional transmission of interlocked signals

An interrupt handling apparatus for a data processing system comprising a plurality of processing units and a working memory to which the units may access through a common bus by means of multilevel priority or access requests. Access requests are forwarded by each unit to a bus access controller preferably made part of the working memory through a single lead for each unit, irrespective of the access request priority level; and if the priority level of an access request is high, a high priority level access request signal is distributed by the high priority level interrupting unit to the other system units, which mask their possible access request of a lower priority level in response to such signal. The bus access controller grants access to a unit at a time on a priority basis determined by a priority network in the controller totally insensitive to any priority level difference of the access requests.

Growing community of inventors

Pregnana Milanese, Italy

Tiziano Maccianti