JPH04172510A - Rtc index register control method - Google Patents

Abstract

PURPOSE:To make a RTC index register possible to carry out normal operation when power supply is turned on by preserving the same value as that stored previously in the RTC index register when resume processing is on effect. CONSTITUTION:When updating a value stored in a RTC (real time clock) register 16, a CPU10 outputs to a register 16 the value to be updated, and further the value is held in a special purpose register 15 for system. In the power supply breaking processing routine, if resume processing is on effect, the same value as that previously stored in register 15 is preserved in a backup memory 12. The power supply processing routine, when resume processing is on effect, reads a value that has been stored in memory 12 and that is the same as the value stored in register 16 until the preceding power supply off, and writes this value in register 16. With this, in register 16, a value that was once reduced when power supply was turned off is restored when power supply is turned on, thereby being able to carry out resume processing properly when turning on power supply.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an RTC index register control method suitable for use in a personal computer having a resume function.

(Prior art) In personal computers, the RTC index register usually does not require external reading, so it has a write-only register configuration, and the value output (written) to the RTC index register is , I couldn't tell when the power was off. Therefore, RT C(
Real-TimeClock), output the value to the RTC index register, and then
If the power is turned off before the TC memory is accessed, the value of the RTC index register will disappear, and in the resume processing performed next time when the power is turned on, the RTC index register value will be lost.
The RTC memory will be accessed according to the contents of the RTC index register without any output to the TC index register, resulting in the inconvenience that resume processing cannot be performed correctly.

(Problems to be Solved by the Invention) As mentioned above, in a personal computer with a resume function, if the power is turned off while the RTC is being controlled in the resume mode, the RTC
The correct value is not held in the index register,
There has been an inconvenience that the memory of the RTC is accessed and therefore the resume processing cannot be performed correctly.

The present invention has been made in view of the above circumstances, and provides an RTC index register control method that allows correct resume processing when the power is turned on even if the power is turned off while the RTC is being controlled in the resume mode. The purpose is to

[Structure of the invention] (Means and effects for solving the problem) The present invention is based on RT
a readable system-dedicated register that retains register information written to the C index register; and means for storing register information retained in the system-dedicated register in the backup memory during power-off processing in resume mode; and a means for writing register information stored in the backup memory to the RTC index register during system initialization processing when power is turned on in resume mode. Even if the process starts from accessing the RTC index register when the power is turned on, the resume process can be executed normally.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

In Figure 1, lO is the CP that controls the entire system.
U, and here, in the power-off processing under the resume setting mode, the RTC index register control processing as shown in FIG. 2 is executed according to the power-off processing routine included in the system control program in the ROMII, During power-on processing, the third
RTC index register control processing as shown in the figure is executed. II is a ROM in which a fixed program is stored, and here the RTC index register control processing shown in FIG. 2 when the power is turned off under the resume setting mode, and the RTC index register control processing shown in FIG. 3 when the power is turned on. A system control program that implements processing is stored.

A memory 12 is used by the system control program to implement the resume function and is backed up by a battery even after the power is turned off, and is herein referred to as a backup memory. A system memory 13 serves as the main memory of the CPU 10, in which a work area including various flags and registers is placed.

14 is an RTC memory that is used by the system control program and other programs and is backed up by a battery even after the power is turned off. 15 is a readable system-only register that holds the value output to the RTC index register 16 under the control of the CPU. 16
is an RTC index register for controlling access to the RTC memory 14, and has a register configuration that allows only writing. 17 is an RTC data register used to control the same RTC memory 14. 18 is a keyboard (KB), and 19 is a display unit (CRT).

Figures 2 and 3 show the RTC in the above embodiment, respectively.
FIG. 2 is a flowchart showing the index register control processing flow, and FIG. FIG. 3 shows an RTC index register control processing flow executed according to an initialization processing routine included in the system control program when the power is turned on in the same resume setting mode.

The operation of an embodiment of the present invention will now be described with reference to FIGS. 1 to 3.

When updating the value of the RTC index register 16 during setup processing, etc., the CPU 10 outputs the updated value to the RTC index register 16, and also outputs the value to the system dedicated register 15.
The value set in the index register 16 is always held in the system dedicated register 15.

When the power is turned off in resume mode, the CPU
Under the control of l0, the RTC index register control process shown in FIG. 2 is executed according to the power cutoff process routine included in the system control program in the ROMII.

In this power cutoff processing routine, if the resume mode is set, that is, if resume processing is enabled, read access is made to the system dedicated register 15,
A value stored in the same register 15 with the same contents as the value stored in the RTC index register 1B until the previous time is obtained, and this value is stored in the backup memory 12.

As a result, even if the value set in the RTC index register 16 disappears when the power is turned off, the same value as the value that disappeared is saved in the backup memory 12 when the power is turned off.

Note that when updating the value of the RTC index register 16 during set-up processing, etc., the CPU 10 outputs the updated value to the RTC index register 1B, and further outputs the value to the system dedicated register 15. R
The value set in the TC index register 16 is always held in the system dedicated register 15.

Also, when turning on the power in resume mode, '
Under the control of CPU10, the RTC index register control process shown in FIG. 3 is executed according to the power-on process routine included in the initialization process routine of the system control program.

In this power-on processing routine, if resume processing is enabled, read access is made to the backup memory 12, and the data stored in the RTC index register 16 until the previous power-off is stored in the backup memory 12. Read the same value as the value and write this value to the RTC index register 16. As a result, the value that once disappeared when the power was turned off is restored to the RTC index register 16 when the power is turned on. Thereby, when the power is turned on in the resume mode, the resume process can be executed normally even if the process starts from accessing the RTC index register 16.

[Effects of the Invention] As detailed above, according to the RTC index register control method of the present invention, there is a readable system-dedicated register that holds register information written to the RTC index register, and power-off processing in resume mode. means for storing the register information held in the system-dedicated register in the backup memory; and means for storing the register information stored in the backup memory in the system initialization process upon power-on in the resume mode. By having the configuration including means for writing to the index register, the resume process can be normally executed even if the process starts from accessing the RTC index register when the power is turned on in the resume mode.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIGS. 2 and 3 are flowcharts showing the RTC index register control processing flow in the above embodiment, and FIG. Figure 3 shows the RTC index register control processing flow executed according to the power-off processing routine included in the system control program in ROMII when the power is turned off in the ROMII. RT executed according to the initialization processing routine
It is a C index register control processing flow. IO...CPU, 11...ROM, 12...Backup memory, 13...System memory, 14...
・RTC memory, 15... System dedicated register, 1
6...RTC index register, 17...RT
C data register, 18...Keyboard (KB), 1
9...Display UniSoto (CRT). Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] A backup memory that stores information for resume processing for at least the system power-off period, and an RTC that stores system-specific information including time information or system configuration information for at least the system power-off period.
In a personal computer comprising a memory, an RTC index register for controlling access to the memory, and an RTC data register, a readable storage means for retaining register information written in the RTC index register, and a resume function are provided. means for storing register information held in the storage means in the backup memory during power-off processing in the mode; and means for storing the register information stored in the backup memory in the power-on processing in the resume mode. 1. An RTC index register control method, comprising means for writing to an index register.