JPH07334343A - Portable computer - Google Patents

Abstract

PURPOSE:To avoid the state of displaying no picture in every place when a power source is turned on. CONSTITUTION:When a first display mode is set at the time of turning the power source on, the display of a display object is wet automatically decided corresponding to whether or not a CRT 28 is connected. When a second display mode is set, on the other hand, both an LCD 27 and the CRT display 28 are defined as the display object. When the high resolution mode of SVGA is designated in the state of disconnecting the CRT 28, a beep tone is generated from a loudspeaker 33 in order to urge the connection of the CRT 28 so that the disconnection of the CRT can be reported to a user. In this case, when the user connects the CRT 28, a picture is displayed on that CRT 28.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laptop type or notebook type personal portable computer.

[0002]

2. Description of the Related Art In recent years, various portable laptop or notebook type personal portable computers have been developed. This type of portable computer is equipped with a flat panel display such as an LCD as a standard, and a CRT display is configured to be selectively connectable. In this case, which display the screen is displayed on when the power is turned on is determined by the display mode information set in the CMOS memory in the system.

Conventionally, the display mode information includes:
"Internal" mode that displays on the LCD screen,
Display on the CRT display “Externa
There was an "1" mode and a "Simultaneous" mode in which both the LCD and CRT displays were displayed simultaneously.

When the "Internal" mode is set, the screen is not displayed on the CRT display even if the CRT display is connected. Further, when the "External" mode is set, if the CRT display is not connected, the screen is not displayed anywhere.

However, in the conventional portable computer having the hot key function, the display mode information of the CMOS memory can be easily rewritten by the hot key operation.
By changing the mode from "xternal" to "Internal" mode, it is possible to easily avoid the situation where the screen is not displayed.

However, in order to realize the hot key function, it is necessary to make the hardware such as a keyboard controller and a CPU highly functional, so that there is a drawback that the cost of the portable computer is increased.

Further, in the past, even when the CRT display is not resumed when the power is turned off by the suspend process during the use of the high resolution screen mode which can be displayed only on the CRT display and the CRT display is removed and then resumed. There is a problem that it cannot be displayed. In this case, the system environment immediately before the power is turned off and the system environment when the power is turned on are different, so it is possible to restart the system as a resume failer (resume failure). All user data will be lost.

[0008]

Conventionally, there is a drawback in that the screen is not displayed anywhere even when the power is turned on, depending on the display mode for designating the display to be displayed and the setting state of the screen mode. . Further, if a hot key function is provided so that the display mode and the like can be changed by key operation, there is a drawback that the cost of the system increases.

The present invention has been made in view of the above circumstances, and provides a portable computer which is inexpensive and has excellent operability, by which a situation where a screen is not displayed anywhere can be avoided with a relatively simple structure. The purpose is to

[0010]

Means and Actions for Solving the Problems
In a portable computer having a flat panel display provided in a computer body and to which a CRT display can be connected, a display controller for controlling display of the flat panel display and the CRT display and controlling a display to be displayed in a designated screen mode. And one of a first display mode for designating a screen display for one of the flat panel display and the CRT display and a second display mode for designating a simultaneous screen display for both the flat panel display and the CRT display. When the display mode information indicates the first display mode and the storage device that stores the display mode information, the display control is performed according to whether or not the CRT display is connected. Means for deciding a display to be displayed on the screen by a controller and having a resolution that can be displayed only on the CRT display when the CRT display is not connected when the display mode information indicates the first display mode. When a screen mode is designated, a means for issuing a warning for prompting the user to connect the CRT display is provided.

In this portable computer,
There are two display modes, first and second,
When the first display mode is set by the user, the display to be displayed is automatically determined depending on whether or not the CRT display is connected. That is, the screen is displayed on the CRT display when the CRT is connected, and displayed on the flat panel display when the CRT is not connected. On the other hand, when the second display mode is set, both the flat panel display and the CRT display are display targets.

Therefore, regardless of whether the first or second display mode is set, it is possible to always display a screen on at least one of the flat panel display and the CRT display regardless of whether the CRT display is connected or not. It is possible to prevent a situation in which no screen is displayed even when the power is turned on.

Further, when the first display mode is set and the screen mode having a resolution that can be displayed only on the CRT display is specified without the CRT display being connected, the connection of the CRT display is made. A warning for prompting the user is issued by, for example, generation of a beep sound, which notifies the user that the CRT display is not connected. In this case, since the display mode is not changed at all, the CR is set by the user.
When the T display is connected, the screen is displayed on the CRT display.

Therefore, it is possible to avoid a situation where the screen is not displayed anywhere with a relatively simple structure, and a portable computer which is inexpensive and has excellent operability is realized.

Further, according to the present invention, in a portable computer having a flat panel display provided in a computer main body and capable of connecting to a CRT display, the flat panel display and the CRT display are controlled to be displayed in a designated screen mode. Display controller for controlling a display to be displayed, the flat panel display and CR
Display mode information indicating one of a first display mode that specifies a screen display for one of the T displays and a second display mode that specifies a simultaneous screen display for both the flat panel display and the CRT display is stored. The storage device, CRT connection detection means for detecting whether or not the CRT display is connected, and the display mode information stored in the storage device are the first.
When indicating the display mode, a means for switching the display displayed on the screen by the display controller according to the detection result of the CRT connection detecting means and information necessary for returning to the state immediately before the power is turned off are saved, and the power is turned on. In response to the resume information for restoring the stored information to reproduce the state immediately before the power is turned off, and whether the display mode information stored in the storage device indicates the first display mode when the power is turned on. A means for determining whether or not to indicate the first display mode, and a detection result of the CRT connection detecting means stored by the resume means immediately before the power is turned off and the CR when the power is turned on.
Based on the detection result of the T connection detection means, it is detected that the CRT connection detection means that detects whether or not the CRT display connected immediately before the power is turned off and that the CRT display is disconnected are detected. At this time, the means for detecting whether or not the screen mode returned to the display controller by the resume means is a screen mode having a resolution that can be displayed only on the CRT display, and a resolution that can be displayed only on the CRT display. CRT when in screen mode
Means for issuing a warning for prompting the user to connect the display.

In this portable computer,
Even if the power is turned off while using the high-resolution screen mode that can be displayed only on the CRT display, and then the power is turned on after the CRT display is removed, the resume failer does not occur and the resume means restores the state immediately before the power was turned off. An attempt is made to restore the screen to the display.

In this case, since the CRT display is not connected, the screen is not actually displayed, but a warning is issued to prompt the connection of the CRT display. After that, when the CRT display is connected, the screen can be normally returned to the CRT display. Therefore, it is possible to prevent the situation where the screen is not displayed anywhere at the time of resume, and to prevent the loss of user data such as display data by effectively operating the resume function even if the environment change occurs such that the CRT display is removed. You can

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the system configuration of a portable computer according to an embodiment of the present invention. This portable computer is a laptop or notebook type personal computer,
As shown, the CPU 11 and the CPU local bus 12
A, ISA specification system bus 12B, main memory 1
3, the system controller 14 is provided.

The CPU 11 is for controlling the entire system and executes the program to be processed stored in the main memory 13. The main memory 13 stores an operating system, an application program to be processed, user data created by the application program, and the like. A part of the main memory 13 is used as a backup RAM for realizing the resume function. This backup RAM is a battery-backed memory, and when the system power is turned off, the system status immediately before the power is turned off is saved and saved in the backup RAM.

The system controller 14 includes a bridge device which connects the CPU local bus 12A and the system bus 12B, and a memory control logic which controls various memories in the system.

On the system bus 12B, as shown,
An I / O controller 15, a BIOSROM 16, a real-time clock (RTC) 17, a display controller 18, a PCMCIA controller 20, a keyboard controller (KBC) 21, and a hard disk drive (HDD) 26 are connected.

The I / O controller 15 controls the I / O devices connected to the serial port 22, the printer / external FDD connected to the parallel port 23, and the built-in FDD. Also, this I /
The O controller 15 includes a DMA controller for direct memory access control and an interrupt controller (PI
C; Programmable Interrupt Controller), system timer (PIT; Programmable Interval Val)
er) two, serial I / O controller (SIO; S
erial Input / Output Controller) etc. are built in.

Further, the I / O controller 15 is provided with a circuit for driving and controlling the speaker 33, an I / O register group used for communication between the power supply controller (PSC) 25 and the CPU 11, and the like. ing.

The BIOS ROM 16 is a system BIOS.
It is for storing an S (basic I / O system), and is composed of a flash memory so that the program can be rewritten. The system BIOS includes an IRT routine executed at power-on, a driver group for controlling various I / O devices, and a setup program for setting / changing the system environment. The driver group includes a video BIOS that controls the display controller 18 in response to a request from the OS or an application program.

The real time clock (RTC) 17 is
It is a timepiece module having its own battery for operation, and has a static RAM 171 (hereinafter, referred to as a CMOS memory) having a CMOS structure in which power is constantly supplied from the battery. The CMOS memory 171 is used to store environment setting information indicating the system operating environment. CMO
The environment setting information of the S memory 171 can be rewritten by starting the setup program. When the setup program is started, the environment setting screen (setup window) as shown in FIG. 2 is displayed, and the input operation for setting / changing the system operating environment can be performed on the setup window. .
As shown in FIG. 2, in this system, various operating environments related to memory, display, I / O port, hard disk, power-on password, and other operating environments such as resume / boot mode are set on the setup window. / Can be changed.

Here, as the environment setting information regarding the display, there is a power-on display mode. This power-on display mode specifies a display that is displayed on the screen when the system is powered on, and has two modes: an "Internal / External" mode and a "Simultaneous" mode.

"Internal / External"
The mode is LCD2 that is standard equipment on the computer.
7 and an RGB connector C provided on the computer body
1 is a display mode in which a screen is displayed on one side of a CRT display 28 that is detachably connected to the LCD 1 and the CR 27.
Which one is displayed on the T display 28 depends on the CRT.
It is determined by whether the display 28 is connected to the RGB connector C1. That is, "Inter
In the state where the "nal / External" mode is set, the screen is displayed on the CRT display 28 if the CRT display 28 is connected, and the screen is displayed on the LCD 27 if the CRT display 28 is not connected.

On the other hand, when the power-on display mode is changed to the "simultaneous" mode, screen display is simultaneously executed on both the LCD 27 and the CRT display 28. In this case, even if the CRT display 28 is not connected, the RGB connector C1 is supplied with the video data from the display controller 18.

The display controller 18 is an LCD
27 and a display controller for controlling the CRT display 28 and supporting SVGA. The display controller 18 displays the LCD 27, the CRT display 28, or simultaneously displays the LCD 27 and the CRT display 28 according to the display mode information set in the register inside the display controller 18. In this case, the display data stored in the video memory (VRAM) 19 by the CPU 11 is converted into LCD and CRT video data, and the LCD 27 and the CRT display 28, respectively.
Is supplied to.

Further, the display controller 18 is
The screen is displayed on the LCD 27 and the CRT display 28 in the screen mode designated by the screen mode information set in the internal register. In this case, the screen modes that can be specified include the VGA specification screen mode and the SVGA specification high resolution screen mode. The resolution of the LCD 27 is fixed, and is 640 × 480 pixels of VGA specification. Therefore, the LCD 27
The screen display can be performed only in the VGA screen mode, and the display in the SVGA high resolution screen mode can be performed only on the CRT display 28.

The high resolution screen mode of SVGA can be set only in the "Internal / External" mode, and is invalidated by the video BIOS in the "Simultaneous" mode.

The PCMCIA controller 20 is an optional 68-pin PCMCIA (Personal C
omputer Memory Card Alternative Associatio
n) Read / write control of the card 29 is performed.

Keyboard controller (KBC) 21
Is for controlling a built-in keyboard 30 built in the computer body as a standard equipment. It scans a key matrix of the built-in keyboard 29 to receive a signal corresponding to a pressed key, and sends it to a predetermined key code ( Scan code). The keyboard controller 26 also has a function of controlling an external keyboard 31 and a mouse 32 that are optionally connected.

FIG. 3 shows an extracted hardware configuration relating to display control, which is a feature of the present invention. I
As shown, the / O controller 15 is provided with a voltage detection circuit 151, a speaker drive circuit 152, a CRT status register 153, and a speaker on / off register 154.

The voltage detection circuit 151 has an RGB connector C.
1 is for detecting whether or not the CRT display 28 is connected, detecting the voltage of a predetermined pin of the RGB connector C1 and checking whether the detected voltage is higher than a predetermined value. Determine if there is a connection. When the CRT display 28 is connected to the RGB connector C1, the voltage value applied to the predetermined pin of the RGB connector C1 is the CRT display 28.
Is reduced by the load resistance of the RGB connector C1
There is no voltage drop when the CRT display 28 is not connected to. Therefore, it is determined that the CRT display 28 is not connected if the voltage value of the predetermined pin of the RGB connector C1 is higher than a predetermined reference voltage, and it is determined that the CRT display 28 is connected if the voltage value is equal to or lower than the reference voltage.

The detection result indicating whether or not the CRT display is connected by the voltage detection circuit 151 is set in the CRT status register 143. The CRT status register 143 is an I / O register readable / writable by the CPU 11, and the CPU 11 reads the CRT status register 143 to read the CRT status register 143.
You can judge whether the display is connected or not. In this case, if the value of the CRT status register 143 is "1", it is determined that the connection is not established, and if the value of the CRT status register 143 is "0", the connection is established.

The speaker drive circuit 152 includes the speaker 33.
Is a device for generating a beep sound by driving the speaker 33. When the flag is set in the speaker on / off register 154, the speaker 33 is driven, and when the flag is reset, the speaker driving is stopped. The speaker on / off register 154 is an I / O register that can be read / written by the CPU 11, and the flag setting / reset for the speaker on / off register 154 is performed by the CPU.
It is executed by 11.

The display controller 18 includes a display mode register 181 and a screen mode register 18
2 etc. are provided. In the display mode register 181, three types of display mode information (LCD display, CRT display, LCD and CRT simultaneous display) indicating the display to be displayed are set by the CPU 11. In the screen mode register 1182, screen mode information for designating one of a plurality of types of screen modes in which the display mode of graphics / text, the resolution, the number of display colors, the character font size, etc. are respectively specified
Set by 1. These screen modes include a high resolution mode of SVGA specifications that cannot be displayed on the LCD 27.

As shown in the figure, the CMOS memory 171 is provided with a configuration storage area for system environment setting such as a power-on display storage area 171a and a power-up mode storage area 171b.

Power-on display storage area 171
In a, the above-mentioned "Internal / Externa
Either the "l" mode or the "Simultaneous" mode is set by the CPU 11. Which mode is set is determined by the setup process using the setup window of FIG.

In the power-up mode storage area 171b, one of the boot mode and the resume mode is set. Which mode is set is determined by the setup process using the setup window of FIG.

Next, the procedure of the display control process when the system is powered on will be described. First, the operation in the case where the boot mode is designated will be described with reference to the flowchart in FIG.

When the system is powered on, the CPU1
1 executes the IRT routine of the BIOS ROM 16 to perform the following processing. That is, the CPU 11
First, the power-on display storage area 171a of the CMOS memory 171 is read, and the currently set power-on display mode is set to "Internal.
/ External ”mode and“ Simultaneo ”
It is determined which of the "us" modes is selected (step S
11, S12).

In the "Simultaneous" mode, the CPU 11 sets the LCD and CR in the display mode register 181 of the display controller 18 in the initial setting process for the display controller 18.
Display mode information indicating simultaneous display of T is set (step S13). After that, various other I / Os are initialized according to the contents of the CMOS memory 171, and then the operating system is activated (step S18).

On the other hand, "Internal / Extern
In the "al" mode, the CPU 11 first reads the CRT status register 153 of the I / O controller 15, and the CRT display 28 displays the RGB connector C1.
It is determined whether or not it is connected to (Sup S14, S
15).

If the CRT display 28 is connected, the CPU 11 sets the display mode information indicating the CRT display in the display mode register 181 of the display controller 18 in the initial setting process for the display controller 18 (step S16). ). Then, after various other I / Os are initialized according to the contents of the CMOS memory 171, the operating system is activated (step S18).

When the CRT display 28 is not connected, the CPU 11 operates the display controller 18
In the initial setting process for, the display mode information indicating the LCD display is set in the display mode register 181 of the display controller 18 (step S17).
Then, after various other I / Os are initialized according to the contents of the CMOS memory 171, the operating system is activated (step S18).

In this way, "Internal / Ext
When the user has set the "ternal" mode, the display to be displayed is automatically determined depending on whether the CRT display 28 is connected or not.
The screen is displayed on the CRT display 28 when the CRT is connected, and the screen is displayed on the LCD 27 when the CRT is not connected.
On the other hand, when the "Simultaneous" mode is set, both the LCD 27 and the CRT display 28 are display targets.

Therefore, "Internal / Ext
Regardless of which mode is set, "CR" or "simultaneous"
LC regardless of whether the T display 28 is connected or not
The screen can be displayed on at least one of the D27 and the CRT display 28, and it is possible to prevent a situation in which the screen is not displayed even when the power is turned on or the system is started up.

Next, referring to the flow chart of FIG.
The operation when the power is turned on when the resume mode is designated will be described. When the system is powered on, the CPU 11 executes the IRT routine of the BIOS ROM 16 to perform the following processing.

That is, the CPU 11 restores the system information saved in the backup RAM in the suspend process executed when the power is turned off to various I / Os, and executes the resume process except for the display controller 18. Next, the CPU 11 performs the resume process of the display controller 18 as follows.

That is, the CPU 11 firstly detects the CMOS
Power-on display storage area 17 of the memory 171
1a, and the currently set power-on display mode is "Internal / Externa".
It is determined whether the mode is the "l" mode or the "Simultaneous" mode (steps S21 and S22).

In the "Simultaneous" mode, the CPU 11 executes the resume process for the simultaneous display of the LCD and the CRT on the display controller 18 (step S23). Here, the display mode information indicating the simultaneous display and the screen mode information stored in the backup RAM are returned to the display mode register 181 and the screen mode register 182 of the display controller 18, respectively. Then, the CPU 11 executes the O that was being executed immediately before the power was turned off.
Control is transferred to S or an application program.

On the other hand, "Internal / Extern
In the "al" mode, the CPU 11 first reads the value of the CRT status register 143 saved in the backup RAM in the suspend process and the value currently set in the CRT status register 153, and establishes the relationship between those values. By investigating, CR during suspend
It is determined whether the T display is removed (steps S24 to S26). In this case, backup RAM
If the value of the CRT status register 143 saved in “0” is “0” and the current value of the CRT status register 153 is “1”, it is determined that the CRT display is detached during suspend. Otherwise, the CRT display is removed during suspend.
It is determined that the RT display has not been removed.

If the CRT display is not removed during suspending, the CPU 11 checks whether or not the CRT display is currently connected according to the value read in step S25 (step S27).

If the CRT is not connected, the CPU 11
Executes a resume process for LCD display (step S28). Here, the display mode information indicating the LCD display and the screen mode information stored in the backup RAM are returned to the display mode register 181 and the screen mode register 182 of the display controller 18, respectively. And the CPU 11
Control is transferred to the OS or application program that was being executed immediately before the power was turned off.

If the CRT is connected, the CPU 11
Executes the resume process for CRT display (step S33). Here, the display mode information indicating the CRT display and the screen mode information stored in the backup RAM are returned to the display mode register 181 and the screen mode register 182 of the display controller 18, respectively. And the CPU 11
Control is transferred to the OS or application program that was being executed immediately before the power was turned off.

On the other hand, when the CRT display is detached during suspending, the CPU 11 first reads the screen mode information stored in the backup RAM, and the screen mode immediately before power-off can be displayed only by the CRT. It is determined whether the high resolution mode is set (steps S29 and S30).

When not in the high resolution mode, the CPU 1
1 sets the display mode information indicating the LCD display in the display mode register 181 of the display controller 18, and restores the screen mode information stored in the backup RAM to the screen mode register 182 (step S31). Then, the CPU 11 shifts control to the OS or application program that was being executed immediately before the power was turned off. Therefore, in this case, instead of the CRT display 28 that was used before the power was turned off, the screen is displayed on the LCD 27.

In the high resolution mode, the CPU 11
In order to prompt the user to connect the CRT display, the speaker-on data is set in the register 154 of the I / O controller 15, and a beep sound is generated from the speaker 33 (step S32). After this, CPU1
1 periodically and repeatedly reads the CRT status register 151, and when detecting a CRT connection, stops driving the speaker 33 and executes resume processing for CRT display (steps S33, S34). .
In this resume process, the display mode information indicating the CRT display and the screen mode information stored in the backup RAM are returned to the display mode register 181 and the screen mode register 182 of the display controller 18, respectively. Then, the CPU 11
Control is transferred to the OS or application program that was being executed immediately before the power was turned off.

As described above, when the power is turned on in the resume mode, the C
Even if the RT display 28 is detached, it does not function as a resume failer and the resume process for returning the screen is executed. In this case, if the display is not in the high resolution mode, the display to be displayed is switched from the CRT display 28 to the LCD 27, and in the high resolution mode, the screen is returned to the CRT display 28 when the CRT display 28 is connected.

Therefore, even if the high resolution mode is set, the state immediately before the power is turned off can be restored without causing data loss as long as the CRT display 28 is connected.

In this embodiment, "Simulta
In the "neous" mode, the case where the setting of the high resolution mode is invalid has been described as an example.
The display controller and video BI in which the setting of the high resolution mode is effective even in the "laneneous" mode
When using OS (in this case, CRT display 2
8 is displayed on the screen only), "Simultane
"Internal / Ext" even in "ous" mode
It is preferable to carry out the processing from step S22 onward as in the case of the "ternal" mode.

Further, here, the CRT display 28
Although the resume process for returning to the screen was executed at the time of connection, the resume process can be started without waiting for the connection of the CRT display 28.

Furthermore, even under the execution environment of the OS or application, "Internal / External"
l "mode, no CRT connection, high-resolution screen mode, beep sounds and CRT
The user may be prompted to make a connection.

[0066]

As described above, according to the present invention, it is possible to avoid the situation where the screen is not displayed anywhere even when the power is turned on with a relatively simple structure without using the hot key function. An inexpensive portable computer with excellent operability is realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall system configuration of a portable computer according to an embodiment of the present invention.

FIG. 2 is an exemplary view showing an example of a setup window for setting the system environment of the portable computer of the embodiment.

FIG. 3 is a view showing a hardware module group for display control provided in the portable computer of the embodiment.

FIG. 4 is a flowchart illustrating an operation executed when the portable computer of the embodiment is powered on in a boot mode.

FIG. 5 is a flowchart illustrating an operation executed when the portable computer of the embodiment is powered on in a resume mode.

[Explanation of symbols]

11 ... CPU, 18 ... Display controller, 27
... LCD, 28 ... CRT display, 33 ... Speaker, 151 ... Voltage detection circuit, 152 ... Speaker drive circuit, 153 ... CRT status register, 171 ... CM
OS memory, 171a ... Power-on display mode storage area, 171b ... Power-up mode storage area, C1 ... RGB connector.

Claims (2)

[Claims] 1. A portable computer having a flat panel display provided in a computer body, to which a CRT display can be connected, the flat panel display and the CRT display being controlled to be displayed, and a display target display in a designated screen mode. A first display mode for designating a screen display for either the flat panel display or the CRT display, the flat panel display and C
A storage device that stores display mode information that indicates one of the second display modes that specifies simultaneous screen display for both RT displays, and the display mode information that is stored in this storage device indicates the first display mode. At this time, in the case where the display controller displays a display according to whether or not the CRT display is connected, and the display mode information stored in the storage device indicates the first display mode, And a means for issuing a warning for prompting the user to connect the CRT display when a screen mode having a resolution that can be displayed only on the CRT display is specified in a state where the CRT display is not connected. Characteristic portable computer. 2. A portable computer having a flat panel display provided in a computer body, to which a CRT display can be connected, the flat panel display and the CRT display being display-controlled, and a display target being displayed in a designated screen mode. A first display mode for designating a screen display for either the flat panel display or the CRT display, the flat panel display and C
A storage device that stores display mode information indicating one of a second display mode that specifies simultaneous screen display for both RT displays, and a CRT that detects whether or not the CRT display is connected
Connection detecting means, and means for switching a display screen-displayed by the display controller according to the detection result of the CRT connection detecting means when the display mode information stored in the storage device indicates the first display mode. , Resume means that saves the information necessary to restore the state immediately before the power was turned off, and that responds to the power-on, restores the saved information and reproduces the state immediately before the power was turned off. Means for determining whether or not the display mode information stored in the storage device indicates the first display mode; and, when it is determined that the display mode information indicates the first display mode, it is stored by the resume means. The detection result of the CRT connection detecting means immediately before the power is turned off and the C when the power is turned on
Based on the detection result of the RT connection detecting means, it is detected that the CRT connection detecting means for detecting whether or not the CRT display connected immediately before the power is turned off and the CRT display are disconnected. At this time, a means for detecting whether or not the screen mode returned to the display controller by the resume means is a screen mode having a resolution that can be displayed only on the CRT display, and a resolution that can be displayed only on the CRT display. A portable computer, comprising means for issuing a warning for prompting the user to connect a CRT display when in the screen mode.