1. An apparatus to store modified data, the apparatus comprising:
a secondary power source for supplying power in the event of a primary power source failure;
a memory module for storing data, the memory module comprising a first portion and a second portion, the first portion configured to receive power from the secondary power source;
a data flow module operably connected to the memory module for controlling data flow into and out of the memory module, the data flow module storing modified data exclusively in the first portion of the memory module.
2. The apparatus of claim 1, wherein the secondary power source is a battery.
3. The apparatus of claim 1, wherein the first portion of the memory module comprises a cache memory for storing modified data.
4. The apparatus of claim 1, wherein the first portion comprises a first nonvolatile storage.
5. The apparatus of claim 1, wherein the data flow module directs modified data to the memory cache of the memory module.
6. The apparatus of claim 1, wherein the data flow module copies modified data to a second nonvolatile storage.
7. The apparatus of claim 1, wherein the first portion comprises more than about one sixty-fourth of the memory module.
8. The apparatus of claim 1, wherein the first portion comprises less than about seven eighths of the memory module.
9. The apparatus of claim 1, wherein the first portion comprises between about one twentieth and about one sixth of the memory module.
10. The apparatus of claim 1, wherein the size of the first portion is automatically determined by the apparatus.
11. The apparatus of claim 1, wherein the data flow module is configured to remove data from the first portion of the memory module when said data has not been accessed for a predetermined time threshold.
12. The apparatus of claim 1, wherein the data flow module is configured to remove data from the first portion of the memory module when a predetermined amount of the first portion has been filled with data.
13. The apparatus of claim 12, wherein the data flow module stores a value associated with a largest amount of first portion occupied by modified data at any given time.
14. The apparatus of claim 12, wherein the data flow module is configured to adjust the predetermined amount of first portion necessary to be filled before data is removed from the first portion, based upon the stored value associated with the largest amount of first portion occupied by modified data.
15. A cache for storing modified data, the cache comprising:
a portion of memory configured to store modified data, said portion backed up by a secondary power source;
a portion of memory configured to store unmodified data, said portion not connected to the secondary power source; and
a refresh module for refreshing the modified data after a primary power source has failed.
16. The cache of claim 15, wherein the portion configured to store modified data comprises more than about one sixty-fourth of the memory.
17. The cache of claim 15, wherein the portion configured to store modified data comprises less than about seven eighths of the memory.
18. The cache of claim 15, wherein the portion configured to store modified data comprises between about one twentieth and about one sixth of the memory.
19. A system to store modified data, the system comprising:
a processor;
a memory module operably connected to the processor, the memory module comprising a cache configured to store volatile data, and a nonvolatile storage configured to store nonvolatile data, the cache comprising a portion of memory dedicated to storing modified data;
a secondary power source for supplying backup power, the secondary power source configured to supply power exclusively to the nonvolatile storage and cache portion dedicated to storing modified data in the event of a primary power source failure;
a data flow module operably connected to the memory module for controlling data flow between the processor and the memory module, the data flow module storing modified data exclusively in the cache and the nonvolatile storage; and
a disk storage unit.
20. The system of claim 19, further comprising a refresh module operably connected to the memory module for refreshing modified data in the cache portion after a power failure.
21. The system of claim 19, wherein the data flow module is configured to remove modified data from the cache of the memory module when said data has not been accessed for a predetermined time threshold.
22. The system of claim 19, wherein the data flow module is configured to remove modified data from the cache of the memory module when a predetermined amount of the cache is filled.
23. A signal bearing medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform an operation to store modified data, the operation comprising:
receiving one or more read and a write commands;
storing data associated with the write command in a nonvolatile storage backed up by a battery source;
storing data associated with the write command in a portion of cache memory backed up by a battery source; and
storing data associated with the read command in a portion of cache memory not backed up by a battery source.
24. The signal bearing medium of claim 23, wherein storing data associated with the write command in a portion of cache memory backed up by a battery comprises determining whether space exists to store the data.
25. The signal bearing medium of claim 232, further comprising staging certain data in the battery backed portion of memory to a disk storage unit.
26. The signal bearing medium of claim 25, further comprising freeing up the space on the battery backed portion of memory where the staged data resided.
27. A method for storing modified data, the method comprising:
receiving a read command and a write command;
storing data associated with the write command in a nonvolatile storage;
storing data associated with the write command in a portion of a cache memory backed up by a battery; and
storing data associated with the read command in a portion of a cache memory not backed up by a battery.
28. The method of claim 27, wherein storing data associated with the write command on a portion of cache memory backed up by a battery comprises determining whether space exists to store the data.
29. The method of claim 27, wherein storing data associated with the write command comprises determining whether to deallocate space associated with that data stored on a portion of cache memory not backed up by a battery.
30. The method of claim 27, wherein storing data associated with the write command comprises finding said data in a portion of cache not backed up by a battery, allocating space for said data in cache backed up by a battery, storing said data in the battery-backed cache and freeing the space in the cache not backed up by a battery where said data existed.
31. An apparatus to store modified data, the apparatus comprising:
means for receiving a read and a write command;
means for storing data associated with the write command in a nonvolatile storage;
means for storing data associated with the write command in a portion of a cache memory backed up by a battery; and
means for storing data associated with the read command in a portion of a cache memory not backed up by a battery.
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 transport trolley having:
at least two interconnected spaced tines that extend parallel with a longitudinal axis of the trolley, wherein each said tine has a forward region, a central region and a rearward region;
a roller housing mounted to each of said forward region and a roller and a roller housing mounted to each said central region or rearward region, wherein said roller housing contain ground-engaging rollers and each said roller housing has a mounting pin for mounting to a said tine; and
steering system including:
distance monitors connected to the forward region and to the central or rearward regions of at least one of the tines for monitoring the distance between the at least one tine (hereafter referred to as the \u201cmonitoring tine\u201d) and at least one sidewall of a container, wherein in use the at least one sidewall extends generally parallel with the longitudinal axis of the trolley;
a drive system which includes hydraulic steering cylinders for moving the rollers relative to the tines as well as for moving the rollers at the forward regions independently of the rollers at the central or rearward regions, wherein pistons of said hydraulic steering cylinders extend parallel with the longitudinal axis of the trolley and are movable between an intermediate position whereby the rollers are in alignment with the longitudinal axis of the trolley and the trolley is steered straight, and an extend position and a retracted position relative to the intermediate position whereby the rollers are out of alignment with the longitudinal axis and the trolley is steerable in directions other than straight; and
an electronic control system, operatively connected to the distance monitors and the drive system, for activating the drive system such that the monitoring tine may be maintained at a pre-set distance from the at least one sidewall.
2. The transport trolley of claim 1, wherein the pre-set distance is programmed by scanning a reflector guard of suitable profile with the distance monitor at the forward region of the monitoring tine, wherein the reflector guard is positioned outside the container and within a plane of the at least one sidewall.
3. The transport trolley of claim 2, wherein the reflector guard has a substantially identical profile to that of the at least one sidewall.
4. The transport trolley of claim 3, wherein the reflector guard is corrugated and the corrugated profile is taken into account when programming the pre-set distance for the distance monitor.
5. The transport trolley of claim 4, wherein steering is achieved by periodically taking maximum and minimum distance readings, than taking an average of those readings and steering to a longitudinally extending central plane of the corrugations.
6. The transport trolley of claim 1 further having an incremental rotary encoder operatively connected to the electronic control system for coordination therewith.
7. The transport trolley of claim 6, wherein the encoder is connected to a ground-contacting wheel of the trolley.
8. The transport trolley of claim 6, wherein data from the encoder is displayed on a display of the electronic control system.
9. The transport trolley of claim 7, wherein said ground-contacting wheel is pivotable out of contact with the ground.
10. The transport trolley of claim 1, wherein a piston of a said steering cylinder is connected to a first end of a said mounting pin and moves the first end relative to a second end of the mounting pin.
11. The transport trolley of claim 10, wherein both the first and second ends of the mounting pin are located within spherical bearings of the tine and both said spherical bearings are slidably mounted to the tine.
12. The transport trolley of claim 1, wherein the electronic control system includes a control panel and display whereby an operator of the trolley is informed of both the position of the monitoring tine relative to the at least one sidewall and that the correct direction of steering is being employed.
13. The transport trolley of claim 12, wherein the control panel and display enable the operator to steer the trolley manually.
14. The transport trolley of claim 1, wherein the roller housings are connected to load supports of the tines.
15. The transport trolley of claim 1, wherein each said distance monitor is a photoelectric sensor.
16. The transport trolley of claim 1, wherein the electronic control system automatically activates the drive system to correct the direction of travel of the trolley when the monitoring tine has moved from the pre-set distance from the at least one sidewall.
17. The transport trolley of claim 1, wherein the electronic control system is programmable so that the pre-set distance can be adjusted.
18. The transport trolley of claim 1, wherein the distance monitors are connected to load supports of the monitoring tine.
19. The transport trolley of claim 1, wherein the pre-set distance is a distance range defined by a maximum allowable distance and a minimum allowable distance from the at least one sidewall.