Data terminal and method of protecting memory items stored in non-persistent memory in a data terminal
First Claim
1. A data terminal comprising:
- a persistent memory for persistent storage of user information items;
a non-persistent memory for temporary storage of user information items, the non-persistent memory being coupled to the persistent memory and including at least a first information item and an indicator indicating whether the first information item has been stored in the persistent memory;
a power supply supplying power to the data terminal, the power supply comprising a power supply rail and a battery;
a power fail detector responsive to the power supply rail for detecting a power fail state in the power supply rail; and
a switching element connected between the battery and the non-persistent memory and responsive to the indicator in the non-persistent memory to selectively couple the battery to the non-persistent memory and to selectively cause the battery to supply power to the non-persistent memory dependent on the indicator and on the power fail detector.
1 Assignment
0 Petitions
Accused Products
Abstract
A data terminal, such as a personal digital assistant, personal computer, pager or other such device has a persistent memory (11), a non-persistent memory (12) including a memory item (15 or 16) and an indicator (17 or 18) indicating whether the memory item has been stored in the persistent memory. The data terminal has a power supply (29), a power fail detector (50) for detecting an imminent power failure in the power supply and a switching element (34) coupling the non-persistent memory (12) to the power supply. The switching element causes the power supply to supply power to the non-persistent memory when the indicator indicates that the second memory item has not been stored in the persistent memory and discontinues supply of power to the non-persistent memory when the power fail detector detects an imminent power failure and the indicator indicates that the second memory item has been stored in the persistent memory.
-
Citations
5 Claims
-
1. A data terminal comprising:
-
a persistent memory for persistent storage of user information items; a non-persistent memory for temporary storage of user information items, the non-persistent memory being coupled to the persistent memory and including at least a first information item and an indicator indicating whether the first information item has been stored in the persistent memory; a power supply supplying power to the data terminal, the power supply comprising a power supply rail and a battery; a power fail detector responsive to the power supply rail for detecting a power fail state in the power supply rail; and a switching element connected between the battery and the non-persistent memory and responsive to the indicator in the non-persistent memory to selectively couple the battery to the non-persistent memory and to selectively cause the battery to supply power to the non-persistent memory dependent on the indicator and on the power fail detector.
-
-
2. A data terminal comprising:
-
a persistent memory for persistent storage of user information items; a non-persistent memory for temporary storage of user information items, the non-persistent memory being coupled to the persistent memory and including at least a first information item and an indicator indicating whether the first information item has been stored in the persistent memory; a battery; a power fail detector responsive to the battery for detecting an imminent power fail state in the battery; and a switching element connected between the battery and the non-persistent memory and responsive to the indicator in the non-persistent memory to selectively couple the battery to the non-persistent memory and to selectively cause the battery to supply power to the non-persistent memory dependent on the indicator and on the power fail detector.
-
-
3. A data terminal comprising:
-
a persistent memory for persistent storage of user information items; a non-persistent memory for temporary storage of user information items, the non-persistent memory being coupled to the persistent memory and including a first information item and an indicator indicating whether the first information item has been stored in the persistent memory; a power supply supplying power to the data terminal; a power fail detector for detecting a power fail state in the power supply; and a switching element coupling the non-persistent memory to the power supply for causing the power supply to supply power to the non-persistent memory when the indicator indicates that the first information item has not been stored in the persistent memory and for discontinuing supply of power to the non-persistent memory when the power fail detector detects a power fail state and the indicator indicates that the first information item has been stored in the persistent memory.
-
-
4. A data terminal comprising:
-
persistent memory for storing user data, the persistent memory including a first memory location; non-persistent memory for storing user data, the non-persistent memory including a second memory location and an indicator associated with the second memory location; logic circuitry coupled to the persistent memory and the non-persistent memory for selectively causing an information item to be transferred from the second memory location to the first memory location and to cause the indicator to indicate that the information item has been transferred; a battery coupled to the logic circuitry, the persistent memory and the non-persistent memory; a battery state detector coupled to the battery for detecting a low battery condition in the battery; and a switching element coupled to the battery, the non-persistent memory and the logic circuitry and responsive to the battery state detector for causing the battery to supply electric power to the non-persistent memory when the battery state detector detects a low battery condition and the indicator indicates that the information item has not been transferred to the persistent memory and for causing the battery not to supply electric power to the non-persistent memory when the battery state detector detects a low battery condition and the indicator indicates that the information item has been transferred to the persistent memory.
-
-
5. In a data terminal having a persistent memory, a non-persistent memory, a power supply, a power fail detector and a switching element coupling the power supply to the non-persistent memory, a method of protecting memory items stored in non-persistent memory comprising the steps of:
-
storing an information item in the non-persistent memory; providing a first indication in the non-persistent memory that the information item has not yet been transferred to the persistent memory; selectively transferring the information item to the persistent memory and substantially simultaneously providing a second indication in the non-persistent memory that the information item has been stored in persistent memory; detecting an imminent power fail state in the power supply; and when the power fail detector detects the imminent power fail state, selectively causing the switching element to continue to supply electric power to the non-persistent memory only when the first indication is provided in the non-persistent memory.
-
Specification