All The Claims

1. A voltage controlled oscillator, comprising:
a resonator configured to oscillate with an initial oscillation frequency during a starting period of oscillation and with a steady oscillation frequency during a steady state oscillation, the resonator including a film bulk acoustic resonator having a series resonance frequency higher than the steady oscillation frequency; and
a negative resistance circuit connected to the resonator, configured to drive the resonator, the negative resistance circuit having a positive increment for reactance in the steady state oscillation compared with reactance in the starting period.
2. The voltage controlled oscillator of claim 1, wherein the resonator comprises:
a phase adjuster connected to the film bulk acoustic resonator; and
a reactance controller connected to the film bulk acoustic resonator or the phase adjuster, the reactance controller having a reactance controlled by a control voltage.
3. The voltage controlled oscillator of claim 1, wherein the initial oscillation frequency is in a range higher than the series resonance frequency and lower than a parallel resonance frequency of the film bulk acoustic resonator.
4. The voltage controlled oscillator of claim 1, wherein, at the series resonance frequency, a ratio of a maximum reactance difference of a reactance controller in a variable range of a control voltage to reactance of the reactance controller at a center value of the control voltage is in a range larger than 0.5, and a ratio of reactance of the reactance controller at the center value of the control voltage to reactance attributable to an electrostatic capacity of the film bulk acoustic resonator is in a range not less than 0.30 and not more than 1.50.
5. The voltage controlled oscillator of claim 4, wherein a ratio of the maximum reactance difference to a difference between a maximum reactance value and a minimum reactance value of the film bulk acoustic resonator is in a range not less than 0.05 and not more than 0.30.
6. A voltage controlled oscillator, comprising:
a resonator driven by a negative resistance circuit, configured to oscillate with an initial oscillation frequency during a starting period of oscillation and with a steady oscillation frequency during a steady state oscillation, the resonator including a film bulk acoustic resonator having a series resonance frequency higher than the steady oscillation frequency, wherein
the negative resistance circuit has a positive increment for reactance in the steady state oscillation compared with reactance in the starting period.
7. A frequency synthesizer, comprising:
a voltage controlled oscillator including a plurality of film bulk acoustic resonators having different resonance frequencies, configured to generate an oscillation signal;
a first frequency divider configured to divide the oscillation signal from the voltage controlled oscillator and to generate a divided oscillation signal;
a second frequency divider configured to divide a reference signal and to generate a divided reference signal;
a phase comparator configured to compare phases of the divided oscillation signal and the divided reference signal and to generate a phase error signal;
a control voltage generator configured to generate a control voltage for the voltage controlled oscillator based on the phase error signal; and
a control circuit configured to generate a control signal based on the control voltage so as to select the film bulk acoustic resonators, and to control an oscillation frequency of the oscillation signal.
8. The frequency synthesizer of claim 7, wherein the voltage controlled oscillator comprises:
a resonator configured to resonate with an initial oscillation frequency during a starting period of oscillation and with a steady oscillation frequency during a steady state oscillation, the resonator including one of the film bulk acoustic resonators having a series resonance frequency higher than the steady oscillation frequency; and
a negative resistance circuit connected to each of the film bulk acoustic resonators, configured to drive the resonator, the negative resistance circuit having a positive increment for reactance in the steady state oscillation compared with reactance in the starting period.
9. The frequency synthesizer of claim 8, wherein the resonator comprises:
a phase adjuster connected to the one of the film bulk acoustic resonators; and
a reactance controller connected to the film bulk acoustic resonator or the phase adjuster, the reactance controller having reactance controlled by the control voltage.
10. The frequency synthesizer of claim 8, wherein the initial oscillation frequency is in a range higher than the series resonance frequency and lower than a parallel resonance frequency of the one of the film bulk acoustic resonators.
11. The frequency synthesizer of claim 8, wherein, at the series resonance frequency, a ratio of a maximum reactance difference of a reactance controller in a variable range of the control voltage to reactance of the reactance controller at a center value of the control voltage is in a range larger than 0.5, and a ratio of reactance of the reactance controller at the center value of the control voltage to reactance attributable to an electrostatic capacity of the one of the film bulk acoustic resonators is in a range not less than 0.30 and not more than 1.50.
12. The frequency synthesizer of claim 11, wherein a ratio of the maximum reactance difference to a difference between a maximum reactance value and a minimum reactance value of the one of the film bulk acoustic resonators is in a range not less than 0.05 and not more than 0.30.
13. A frequency synthesizer, comprising:
a voltage controlled oscillator including a plurality of film bulk acoustic resonators having different resonance frequencies, configured to generate an oscillation signal controlled by a control circuit by dividing the oscillation signal from the voltage controlled oscillator to generate a divided oscillation signal, by dividing a reference signal to generate a divided reference signal, by comparing phases of the divided oscillation signal and the divided reference signal to generate a phase error signal, and by generating a control voltage for the voltage controlled oscillator based on the phase error signal, wherein
the control circuit generates a control signal based on the control voltage so as to select the film bulk acoustic resonators, and controls an oscillation frequency of the oscillation signal.
14. A communication apparatus, comprising:
a frequency synthesizer configured to provide an oscillation signal, including:
a voltage controlled oscillator including a plurality of film bulk acoustic resonators having different resonance frequencies, configured to generate the oscillation signal;
a first frequency divider configured to divide the oscillation signal from the voltage controlled oscillator and to generate a divided oscillation signal;
a second frequency divider configured to divide a reference signal and to generate a divided reference signal;
a phase comparator configured to compare phases of the divided oscillation signal and the divided reference signal and to generate a phase error signal;
a control voltage generator configured to generate a control voltage for the voltage controlled oscillator based on the phase error signal; and
a control circuit configured to generate a control signal based on the control voltage so as to select the film bulk acoustic resonators, and to control an oscillation frequency of the oscillation signal;

a receiver configured to convert a high frequency receiving signal into an intermediate frequency receiving signal by use of the oscillation signal;
a baseband processor configured to demodulate the intermediate frequency receiving signal and to modulate a transmitting signal; and
a transmitter configured to transmit a radio frequency transmitting signal provided by converting the modulated transmitting signal by use of the oscillation signal.
15. The communication apparatus of claim 14, wherein the voltage controlled oscillator comprises:
a resonator configured to resonate with an initial oscillation frequency during a starting period of oscillation and with a steady oscillation frequency during a steady state oscillation, the resonator including one of the film bulk acoustic resonators having a series resonance frequency higher than the steady oscillation frequency; and
a negative resistance circuit connected to each of the film bulk acoustic resonators, configured to drive the resonator, the negative resistance circuit having a positive increment for reactance in the steady state oscillation compared with reactance in the starting period.
16. The communication apparatus of claim 15, wherein the resonator comprises:
a phase adjuster connected to the one of the film bulk acoustic resonators; and
a reactance controller connected to the film bulk acoustic resonator or the phase adjuster, the reactance controller having reactance controlled by the control voltage.
17. The communication apparatus of claim 15, wherein the initial oscillation frequency is in a range higher than the series resonance frequency and lower than a parallel resonance frequency of the one of the film bulk acoustic resonators.
18. The communication apparatus of claim 15, wherein, at the series resonance frequency, a ratio of a maximum reactance difference of a reactance controller in a variable range of the control voltage to reactance of the reactance controller at a center value of the control voltage is in a range larger than 0.5, and a ratio of reactance of the reactance controller at the center value of the control voltage to reactance attributable to an electrostatic capacity of the one of the film bulk acoustic resonators is in a range not less than 0.30 and not more than 1.50.
19. The communication apparatus of claim 18, wherein a ratio of the maximum reactance difference to a difference between a maximum reactance value and a minimum reactance value of the one of the film bulk acoustic resonators is in a range not less than 0.05 and not more than 0.30.

The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.

1. A protection device to protect an electronic apparatus, the protection device comprising:
a motion-detection device, to supply at least one alert signal in response to conditions of motion of the protection device;
a counter;
a first logic circuit, to increment the counter in a presence of a first value of the alert signal, in a first operating condition; and
a second logic circuit, to generate a protection signal on a basis of a count value of the counter;
wherein the first logic circuit is configured to decrement the counter in a presence of a second value of the alert signal, in the first operating condition.
2. The device according to claim 1 wherein the first operating condition is defined by an inactive value of the protection signal.
3. The device according to claim 1 wherein the first logic circuit is configured to increment the counter iteratively by an increment step in the presence of the first value of the alert signal and to decrement the counter iteratively by a decrement step in the presence of the second value of the alert signal, in the first operating condition.
4. The device according to claim 3 wherein the increment step and the decrement step of the counter are programmable.
5. The device according to claim 1 wherein the second logic circuit is configured to switch the protection signal and to reset the counter if the count value has reached a first threshold, in the first operating condition.
6. The device according to claim 1 wherein the first logic circuit is configured to increment the counter in the presence of the second value of the alert signal and to decrement the counter in the presence of the first value of the alert signal, in a second operating condition.
7. The device according to claim 6 wherein the second operating condition is defined by an active value of the protection signal.
8. The device according to claim 6 wherein the second logic circuit is configured to switch the protection signal and to reset the counter if the count value has reached a second threshold, in the second operating condition.
9. The device according to claim 1 wherein the motion-detection device includes:
an inertial sensor, to generate motion signals correlated to conditions of motion of the protection device; and
a processing circuit, coupled to the inertial sensor to supply the alert signal in response to configurations of the motion signals.
10. The device according to claim 9 wherein the inertial sensor is a microelectromechanical sensor.
11. The device according to claim 1 wherein the motion-detection device, the counter, the first logic circuit, and the second logic circuit are housed in a single packaging, provided with a terminal to make the protection signal available externally.
12. An electronic apparatus, comprising:
a microprocessor;
a peripheral unit controlled by the microprocessor; and
a safety device coupled to the microprocessor to supply a protection signal, the safety device including:
a motion-detection device to supply at least one alert signal in response to a condition of motion;
a counter coupled to said motion-detection device;
a first logic circuit coupled to said counter, to increment the counter in response to a first value of the alert signal, in a first operating condition; and
a second logic circuit coupled to said counter, to generate said protection signal based on a count value of the counter;
wherein the first logic circuit is configured to decrement the counter in response to a second value of the alert signal, in the first operating condition.
13. The apparatus according to claim 12 wherein the microprocessor is configured to bring the peripheral unit into a safety configuration, in response to the protection signal.
14. The apparatus of claim 12 wherein the motion-detection device includes:
an inertial sensor, to generate motion signals correlated to said condition of motion; and
a processing circuit, coupled to the inertial sensor to supply the alert signal in response to particular configurations of the motion signals.
15. The apparatus of claim 14 wherein said microprocessor, peripheral unit, and safety device are part of a portable computer, and wherein said inertial sensor and said processing circuit are located on different semiconductor chips of said portable computer.
16. A method for protecting an electronic apparatus, the method comprising:
detecting conditions of motion of the electronic apparatus;
incrementing an index in a presence of the conditions of motion, in a first operating condition;
generating a protection signal on a basis of the index; and
decrementing the index in an absence of the conditions of motion, in the first operating condition.
17. The method according to claim 16 wherein the first operating condition is defined by an inactive value of the protection signal.
18. The method according to claim 16 wherein said incrementing includes incrementing the index iteratively by an increment step and said decrementing includes decrementing the index iteratively by a decrement step, in the first operating condition.
19. The method according to claim 18, further comprising programming the increment step and the decrement step.
20. The method according to claim 16, further comprising switching the protection signal and resetting the index, if the index has reached a first threshold, in the first operating condition.
21. The method according to claim 16, further comprising:
decrementing the index in the presence of the conditions of motion, in a second operating condition; and
incrementing the index in the absence of the conditions of motion, in the second operating condition.
22. The method according to claim 21 wherein the second operating condition is defined by an active value of the protection signal.
23. The method according to claim 22, further comprising switching the protection signal and resetting the index, if the index has reached a second threshold, in the second operating condition.
24. The method according to claim 16 wherein said detecting conditions of motion includes:
using an inertial sensor, to generate motion signals correlated to conditions of motion of the electronic apparatus; and
supplying an alert signal in response to configurations of the motion signals.
25. The method according to claim 24 wherein the alert signal is a free-fall signal.
26. The method according to claim 24 wherein the alert signal is a roll signal.
27. An electronic apparatus, comprising:
means for detecting a condition of motion;
means for changing an index to increment said index in response to detected presence of said condition of motion, in a first operating condition; and
means for generating a protection signal based on a value of the index,
wherein said means for changing decrements the index in response detected absence of said condition of motion, in the first operating condition.
28. The apparatus of claim 27, further comprising:
a microprocessor; and
a peripheral unit controlled by the microprocessor, wherein said processor is adapted to receive said protection signal to place said peripheral unit in a protective configuration.
29. The apparatus of claim 27 wherein said value of the index is a count value of a counter.
30. The apparatus of claim 27 wherein the first operating condition is defined by an inactive value of the protection signal.

1. A propulsion apparatus comprising:
axially spaced apart counter-rotatable forward and aft rows of forward and aft propellers mounted on forward and aft rotatable frames respectively and rotatable about a centerline axis,
an exhaust flowpath which passes through the forward and aft rotatable frames,
forward and aft pitch change systems including hydraulic forward and aft pitch change actuators mounted on the forward and aft rotatable frames and connected to and operable for controlling and setting pitch of the forward and aft propellers respectively,
a hydraulic fluid supply mounted outboard of the forward and aft rotatable frames and hydraulically connected to forward and aft rotary unions including forward and aft union rotors mounted within forward and aft union stators respectively,
the forward and aft rotary unions operable for transferring hydraulic fluid between the forward and aft union stators and the forward and aft union rotors respectively, the forward union rotor hydraulically connected to the aft pitch change actuators for transferring the hydraulic fluid from the forward rotary union to the aft pitch change actuators, and
the aft union rotor hydraulically connected to the forward pitch change actuators for transferring the hydraulic fluid from the aft rotary union to the forward pitch change actuators.
2. A propulsion apparatus as claimed in claim 1, further comprising the forward and aft rotary unions axially spaced apart and operable for transferring the hydraulic fluid radially inwardly and outwardly between the forward and aft union stators and the forward and aft union rotors respectively.
3. A propulsion apparatus as claimed in claim 2, further comprising forward and aft drive shafts drivingly connected to the forward and aft rotatable frames respectively and the aft union rotor including an annular rotor body integral with the forward drive shaft.
4. A propulsion apparatus as claimed in claim 1, further comprising:
forward and aft rotatable struts of the forward and aft rotatable frames respectively extending radially across the exhaust flowpath,
the forward and aft pitch change actuators being hydraulic rotary actuators and mounted radially inwardly of the exhaust flowpath in a one to one ratio with the forward and aft rotatable struts of the forward and aft rotatable frames respectively, and
forward and aft rotatable shafts extending through the forward and aft rotatable struts and connecting the forward and aft pitch change actuators to the forward and aft propellers respectively in a one to one ratio.
5. A propulsion apparatus as claimed in claim 4, further comprising the forward and aft rotary unions operable for transferring hydraulic fluid radially inwardly and outwardly between the forward and aft union stators and the forward and aft union rotors respectively.
6. A propulsion apparatus as claimed in claim 5, further comprising forward and aft drive shafts drivingly connected to the forward and aft rotatable frames respectively and the aft union rotor including an annular rotor body integral with the forward drive shaft.
7. A propulsion apparatus as claimed in claim 6, further comprising:
the forward union rotor extending aftwardly through the aft union rotor,
the aft union rotor including an annular rotor body integral with the forward drive shaft,
the forward and aft union rotors respectively carrying at least in part fluid passageways,
the fluid passageways carried by the forward union rotor in fluid communication with the hydraulic fluid forward supply and return lines and the aft supply and return rotatable lines respectively, and
the fluid passageways carried by the annular rotor body within the aft union rotor in fluid communication with the hydraulic fluid aft supply and return lines and the forward supply and return rotatable lines respectively.
8. A propulsion apparatus as claimed in claim 7, further comprising:
each of the forward and aft union stators including at least first and second fluid chambers having at least first and second stator channels respectively extending radially outwardly from and open through an annular radially inner stator surface of the forward and aft union stators,
each of the fluid chambers having at least one inlet port connected to the hydraulic fluid supply, and
the fluid passageways in fluid communication with the fluid chambers.
9. A propulsion apparatus as claimed in claim 8, further comprising:
the aft union rotor including an annular rotor stator race mounted on the annular rotor body,
a radially outer rotor surface of the annular rotor stator race in slidably sealing engagement with the inner stator surface,
transfer holes in fluid communication with the fluid chambers and radially extending entirely through the annular rotor stator race and the annular rotor body to an annular rotary manifold mounted to the annular rotor body,
the transfer holes in fluid communication with the fluid passageways extending axially aftwardly through the rotary manifold, and
the fluid passageways including intermediate tubes in part connecting portions of the fluid passageways in the rotary manifold to radial sections of the fluid passageways.
10. A propulsion apparatus as claimed in claim 1, further comprising:
the forward and aft rotary unions integrated in a single nested rotary union,
the forward and aft union stators integrated in a common single stator, and
the nested rotary union operable for transferring hydraulic fluid radially inwardly and outwardly between the common single stator and the forward and aft union rotors.
11. A propulsion apparatus as claimed in claim 10, further comprising:
a flowpath which passes through the forward and aft rotatable frames,
forward and aft rotatable struts of the forward and aft rotatable frames respectively extending radially across the exhaust flowpath,
the forward and aft pitch change actuators being hydraulic rotary actuators and mounted radially inwardly of the flowpath in a one to one ratio with the forward and aft rotatable struts of the forward and aft rotatable frames respectively, and
forward and aft rotatable shafts extending through the forward and aft rotatable struts and connecting the forward and aft pitch change actuators to the forward and aft propellers respectively in a one to one ratio.
12. An aircraft gas turbine engine comprising:
a gas generator upstream and operable to power a power turbine,
a nacelle surrounding at least the gas generator,
axially spaced apart counter-rotatable forward and aft rows of forward and aft propellers mounted on forward and aft rotatable frames respectively and rotatable about a centerline axis,
the power turbine drivingly connected to the forward and aft rotatable frames,
forward and aft pitch change systems including hydraulic forward and aft pitch change actuators mounted on the forward and aft rotatable frames and connected to the forward and aft propellers and operable for controlling and setting pitch of the forward and aft propellers respectively,
a hydraulic fluid supply mounted outboard of the forward and aft rotatable frames and connected to forward and aft rotary unions,
the forward and aft rotary unions including forward and aft union rotors mounted within forward and aft union stators and operable for transferring hydraulic fluid between the forward and aft union stators and the forward and aft rotary union rotors respectively,
the forward union rotor hydraulically connected and operable to transfer the hydraulic fluid to the aft pitch change actuator, and
the aft union rotor hydraulically connected and operable to transfer the hydraulic fluid to the forward pitch change actuator.
13. An engine as claimed in claim 12, further comprising:
a flowpath which passes through the forward and aft rotatable frames,
forward and aft rotatable struts of the forward and aft rotatable frames respectively extending radially across the exhaust flowpath,
the forward and aft pitch change actuators being hydraulic rotary actuators and mounted radially inwardly of the flowpath in a one to one ratio with the forward and aft rotatable struts of the forward and aft rotatable frames respectively, and
forward and aft rotatable shafts extending through the forward and aft rotatable struts and connecting the forward and aft pitch change actuators to the forward and aft propellers respectively in a one to one ratio.
14. An engine as claimed in claim 13, further comprising the forward and aft rotary unions operable for transferring hydraulic fluid radially inwardly and outwardly with respect to the centerline axis between the forward and aft union stators and the forward and aft union rotors respectively.
15. An engine as claimed in claim 14, further comprising forward and aft drive shafts counter-rotatably connected to the power turbine and drivingly connected to the forward and aft rotatable frames respectively and the aft union rotor including an annular rotor body integral with integral with the forward drive shaft.
16. An engine as claimed in claim 13, further comprising:
a power turbine rotor of the power turbine rotatably mounted on and between axially spaced apart forward and aft structural turbine frames of the engine,
the power turbine rotor drivingly connected to an epicyclic gearbox, and
the epicyclic gearbox drivingly connected by forward and aft drive shafts to the forward and aft rotatable frames for counter-rotatably driving the forward and aft rotatable frames and the forward and aft propellers mounted thereon.
17. An engine as claimed in claim 16, further comprising:
the forward union stator mounted on the forward structural turbine frame and the forward union stator connected to the hydraulic fluid supply by hydraulic fluid forward supply and return lines,
the aft union stator mounted on the aft structural turbine frame and the aft union stator connected to the hydraulic fluid supply by hydraulic fluid aft supply and return lines,
the forward hydraulic rotary union operable for transferring pressurized hydraulic fluid between the hydraulic fluid forward supply and return lines and aft supply and return rotatable lines respectively,
the aft hydraulic rotary union operable for transferring the pressurized hydraulic fluid between the hydraulic fluid aft supply and return lines and forward supply and return rotatable lines respectively,
the forward union rotor connected to the aft supply and return rotatable lines mounted in the aft rotatable frame and connected to the aft pitch change actuators, and
the aft union rotor connected to the forward supply and return rotatable lines mounted in the forward rotatable frame and connected to the forward pitch change actuators.
18. An engine as claimed in claim 17, further comprising:
the forward union rotor extending aftwardly through the aft union rotor,
the aft union rotor including an annular rotor body integral with the forward drive shaft,
the forward and aft union rotors respectively carrying at least in part fluid passageways,
the fluid passageways carried by the forward union rotor in fluid communication with the hydraulic fluid forward supply and return lines and the aft supply and return rotatable lines respectively, and
the fluid passageways carried by the annular rotor body within the aft union rotor in fluid communication with the hydraulic fluid aft supply and return lines and the forward supply and return rotatable lines respectively.
19. An engine as claimed in claim 18, further comprising:
each of the forward and aft union stators including at least first and second fluid chambers having at least first and second stator channels respectively extending radially outwardly from and open through an annular radially inner stator surface of the forward and aft union stators,
each of the fluid chambers having at least one inlet port connected to the hydraulic fluid supply, and
the fluid passageways in fluid communication with the fluid chambers.
20. An engine as claimed in claim 19, further comprising:
the aft union rotor including an annular rotor stator race mounted on the annular rotor body,
a radially outer rotor surface of the annular rotor stator race in slidably sealing engagement with the inner stator surface,
transfer holes in fluid communication with the fluid chambers and radially extending entirely through the annular rotor stator race and the annular rotor body to an annular rotary manifold mounted to the annular rotor body, and
the transfer holes in fluid communication with the fluid passageways extending axially aftwardly through the rotary manifold.
21. An engine as claimed in claim 20, further comprising the fluid passageways including intermediate tubes in part connecting portions of the fluid passageways in the rotary manifold to radial sections of the fluid passageways.
22. An engine as claimed in claim 12, further comprising:
the forward and aft rotary unions integrated in a single nested rotary union,
the forward and aft union stators integrated in a common single stator, and
the nested rotary union operable for transferring hydraulic fluid radially inwardly and outwardly between the common single stator and the forward and aft union rotors.
23. An engine as claimed in claim 22, further comprising:
a flowpath which passes through the forward and aft rotatable frames,
forward and aft rotatable struts of the forward and aft rotatable frames respectively extending radially across the exhaust flowpath,
the forward and aft pitch change actuators being hydraulic rotary actuators and mounted radially inwardly of the flowpath in a one to one ratio with the forward and aft rotatable struts of the forward and aft rotatable frames respectively, and
forward and aft rotatable shafts extending through the forward and aft rotatable struts and connecting the forward and aft pitch change actuators to the forward and aft propellers respectively in a one to one ratio.
24. A propulsion apparatus as claimed in claim 1, further comprising the forward and aft rotatable frames counter-rotatably mounted on a structural frame and the counter-rotatable forward and aft rows of forward and aft propellers located forward or aft of the structural frame.

The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.

What is claimed is:

1. A bypass system for a data cache, comprising:
two ports to the data cache;
registers for multiple data entries;
a bus connection for accepting read and write operations to the cache; and
address matching and switching logic;
characterized in that write operations that hit in the data cache are stored as elements in the bypass structure before the data is written to the data cache, and read operations use the address matching logic to search the elements of the bypass structure to identify and use any one or more of the entries representing data more recent than that stored in the data cache memory array, such that a subsequent write operation may free a memory port for a write stored in the bypass structure to be written to the data cache memory array.
2. The bypass system of claim 1 wherein the memory operations are limited to 32 bits, and there are six distinct entries in the bypass system.
3. A data cache system comprising:
a data cache memory array; and
a bypass system connected to the data cache memory array by two ports, and to a bus for accepting read and write operations to the system, and having address matching and switching logic;
characterized in that write operations that hit in the data cache are stored as elements in the bypass structure before the data is written to the data cache, and read operations use the address matching logic to search the elements of the bypass structure to identify and use any one or more of the entries representing data more recent than that stored in the data cache memory array, such that a subsequent write operation may free a memory port for a write stored in the bypass structure to be written to the data cache memory array.
4. The system of claim 3 wherein the memory operations are limited to 32 bits, and there are six distinct entries in the bypass system.
5. A method for eliminating stalls in read and write operations to a data cache, comprising steps of:
(a) implementing a bypass system having multiple entries and switching and address matching logic, connected to the data cache memory array by two ports and to a bus for accepting read and write operations;
(b) storing write operations that hit in the cache as entries in the bypass structure before associated data is written to the cache;
(c) searching the bypass structure entries by read operations, using the address matching and switching logic to determine if entries in the bypass structure represent newer data than that available in the data cache memory array; and
(d) using the opportunity of a subsequent write operation to free a memory port for simultaneously writing from the bypass structure to the memory array.
6. The method of claim 5 wherein the memory operations are limited to 32 bits, and there are six distinct entries in the bypass system.