Portable computer with memory management system and method for prolonging the lifetime of internal battery

A memory management method for use in a portable computer to prolong the lifetime of an internal battery in the portable computer. The portable computer includes a non-volatile memory storage device. When the portable terminal is operating from the internal battery or cell, a recording operation is performed in an unused memory region and an address value of data to be deleted is registered in a delete queue, rather than being deleted at that time. Later, when the portable terminal is connected to an external power source, data to be deleted is deleted all at the same time, thereby reducing power consumption of the battery or cell in the portable computer. This method utilizes less capacity of the cell and prolongs operation time of the internal battery cell. Data can be recovered when a user desires recovery of the data unless the data corresponding to the address values recorded in the delete queue has already been deleted.

BACKGROUND OF THE INVENTION 
The present invention relates to a memory management method for use in a 
portable computer or terminal. More particularly, the present invention 
relates to a memory management method for prolonging the lifetime of an 
internal battery in the portable computer or terminal having a 
non-volatile memory. 
As computer information processing capability increases, the number and 
size of programs increase. As a result, the memory contained in a computer 
becomes larger and larger. Typically, a computer or portable terminal 
includes two types of memory--volatile memory and non-volatile memory. 
Non-volatile memory is a storage device for maintaining stored information 
even when power is not applied thereto. An EEPROM or flash memory is an 
example of a non-volatile memory. Volatile memory, on the other hand, does 
not retain the stored information when power is removed. 
FIG. 1 illustrates a flowchart diagram of a data recording method of a 
general recording system using a non-volatile memory as a storage device. 
In step 110, a determination is made as to whether a data recording 
command for recording data is received. If the data recording command is 
received, data previously stored in a corresponding region in memory is 
deleted (step 120). Then, new data is recorded in the corresponding region 
in the memory (step 130). That is, when new data is recorded, the previous 
data recorded in the corresponding region in the memory is deleted 
according to a predetermined sequence, to allow for the recording of the 
new data. Thus, a controller such as a CPU continuously monitors the state 
of the memory for recording and deleting data. Such a continuous memory 
monitor of the controller causes unnecessary power consumption, and 
additional power consumption occurs due to the deleting and recording of 
data. Moreover, in a portable terminal which uses a limited capacity of 
power source (i.e., a battery such as a galvanic cell) power operation 
time is shortened due to power consumption resulting from frequent data 
deleting and recording operations. 
Thus, a computer or portable terminal using a non-volatile memory requires 
a new memory management method capable of prolonging the lifetime of an 
internal cell. 
SUMMARY OF THE INVENTION 
To solve the above problems, it is an object of the present invention to 
provide a memory management method in a portable terminal, in which a 
recording operation is first performed in an unused memory region, an 
address value for data to be deleted is registered in a delete queue, and 
all data to be deleted is deleted at a time when external power is 
supplied, thereby prolonging operation time of the internal cell. 
To accomplish the above and other objects of the present invention, there 
is provided a memory management method in a portable terminal, in which 
power is supplied from an internal cell or an external power source and a 
non-volatile memory is used as a storage device. The memory management 
method includes the steps of: (a) creating a delete queue to register 
address values in a memory region in which data to be deleted has been 
recorded; (b) judging whether a recording data in the memory is received; 
(c) judging whether an idle region exists in the memory when the recording 
command is applied; (d) recording data in the corresponding idle region 
when the idle region exists; (e) judging whether a delete command for 
deleting the data recorded in the memory is received; (f) registering in 
the delete queue corresponding address values of the memory region in 
which the data to be deleted has been recorded, when the delete command is 
input; (g) judging whether power is supplied from the external power 
source; and (h) deleting the address values registered in the delete queue 
and the data of the corresponding regions indicated by the address values 
when the power is supplied from the external power source.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Preferred embodiments of the present invention will be described with 
reference to the accompanying drawings. 
FIG. 2 shows a portable terminal including a cell 21 as a main power 
supply. The cell 21 supplies power to a power supply circuit 23, which 
also receives power from an external power source 22. The external power 
source 22 is located outside of the portable terminal, and is connected to 
the power supply circuit 23 to supply power to the portable terminal or to 
supply power for charging the cell 21. The power supply circuit 23 
supplies the power applied from the cell 21 or the external power source 
22 to a central processing unit (CPU) 25. An input/output (I/O) terminal 
24 is connected between the power supply circuit 23 and the CPU 25 to 
discriminate the power applied from both power sources 21 and 22. The I/O 
terminal 24 detects a point of time at which power is supplied from the 
external power source 22 to the power supply circuit 23. The portable 
terminal also includes a ROM and RAM 26 and a non-volatile memory 27. The 
CPU 25 controls recording and deleting of data as will be described in 
more detail below. A key input unit 28 receives a key signal from a user 
and is connected to the CPU 25. 
FIG. 3 shows a flowchart diagram of a memory management method for a 
portable terminal according to a preferred embodiment of the present 
invention. The memory management method will be described in more detail 
with reference to FIGS. 2 and 3. 
The CPU 25 detects a key signal input from the key input unit 28 and 
determines whether a data recording command is input or a data recording 
command is generated for the data produced during execution of a program 
(step 310). If a data recording command is not received, the program 
proceeds to step 350. However, if a data recording command is received, it 
is determined whether an idle region (a region where no data is recorded) 
exists in the non-volatile memory 27 (step 320). If an idle region exists, 
data is recorded in the idle region (step 330). If an idle region does not 
exist (with a size at least as large as the data to be recorded), a 
minimum recording region is made for recording the data. That is, 
previously recorded data is deleted, so that a region necessary for 
recording the new data is available (step 340). Then the program proceeds 
to step 330. 
Subsequently, it is determined whether a data deletion command is received 
as an input (step 350). If a data deletion command is not received, the 
program proceeds to step 370. However, if a data deletion command is 
input, address values of the data to be deleted are recorded in a delete 
queue (step 360). Then, the CPU 25 determines whether the external power 
source 22 is connected to the portable terminal (step 370). This 
determination is made based on the I/O terminal 24 which detects whether 
the external power source 22 is connected. That is, from an interrupt mode 
or polling mode, the CPU 25 checks the status of the I/O terminal 24 to 
determine whether the portable terminal is connected or disconnected to 
the external power source 22. When the external power source 22 is 
connected to the portable terminal and external power is supplied thereto, 
the CPU 25 deletes all of the address values recorded in the delete queue 
and the data of the corresponding region indicated by the address values 
(step 380). This process is performed at one time. Meanwhile, if the 
external power source 22 is not connected thereto, the program returns to 
step 310. Thus, in this case, the address values and corresponding data is 
not deleted. 
FIGS. 4A through 4F illustrate data recording and deleting operations in 
the memory according to the memory management method. FIGS. 4A through 4F 
show a memory map of data recording regions and addresses A1, A2, A3 and 
A4 each a uniformly divided recording region in the non-volatile memory 
27, and a delete queue for registering the address values of data to be 
deleted among the data recorded in the memory map. The delete queue has a 
first-in-first-out pattern for sequentially registering data to be 
deleted. The delete queue is set in a portion in the non-volatile memory 
27, or set in a certain region of an external memory such as a ROM and RAM 
26. 
FIG. 4A shows a state where no data is recorded in the non-volatile memory 
27. FIG. 4B shows a state where data D1 is recorded in regions having the 
address values A1 and A2 of the non-volatile memory 27. That is, when data 
is recorded, data is recorded in the empty regions having address values 
A1, A2, A3 and A4 of the non-volatile memory 27 as shown in FIG. 4A. FIG. 
4C shows a change of the memory map and delete queue when data D2 is 
applied to update the data D1 recorded in the non-volatile memory 27. 
Here, the regions which can be used for recording are the idle regions 
having address values of A3 and A4. The data D2 for updating the data D1 
is recorded in one of the empty regions. Also, the address values A1 and 
A2 of the memory map in which the previous data D1 has been recorded are 
registered in the delete queue one after the other. 
Meanwhile, the available idle regions are insufficient for recording data 
D3, for example, where the data D3 consumes two regions and only one idle 
region remains as shown in FIG. 4C. Here, if data D3 to be recorded 
requires two idle regions, the oldest address values among the address 
values registered in the delete queue and the previous data recorded in 
the corresponding regions indicated by the oldest address values are 
deleted. Therefore, the oldest address value A1 is deleted, and the 
previous data which is D1 recorded in the regions indicated by the address 
values A1 is deleted. FIG. 4D shows a memory map from which the data has 
been deleted in the region A1 and a delete queue from which the address 
value A1 has been deleted. When a necessary idle region is secured in the 
above operation, data D3 is recorded in the regions indicated by the 
address values A1 and A4. FIG. 4E shows that an address value A3 in the 
memory region in which the previous data D2 has been recorded is recorded 
in the delete queue when new data D3 updates previously recorded data D2. 
FIG. 4F shows that address values A3 and A2 registered in the delete queue 
and data D1 and D2 in the regions indicated by the address values are 
deleted all at the same time when external power is input. 
As described above, the present invention minimizes a deletion process for 
previously recorded data when new data is recorded, thereby reducing power 
consumption of a cell in the portable terminal using a limited capacity 
cell and prolonging the lifetime of the cell. Also, the present invention 
can recover data when a user desires recovery of the data, unless the data 
corresponding to address values recorded in the delete queue have already 
been deleted. 
There has thus been shown and described a novel memory management method 
for use in a computer or portable terminal which fulfills all the objects 
and advantages sought therefor. Many changes, modifications, variations 
and other uses and applications of the subject invention will, however, 
become apparent to those skilled in the art after considering the 
specification and the accompanying drawings which disclose preferred 
embodiments thereof. All such changes, modifications, variations and other 
uses and applications which do not depart from the spirit and scope of the 
invention are deemed to be covered by the invention which is limited only 
by the claims which follow.