JPH1165720A - Computers and computer systems - Google Patents

Abstract

(57) [Object] To provide a computer which can reduce the size and weight of a computer main body and can be operated for a long time by a battery when carried. A detachment detection unit for a docking I / F detects whether or not an extension unit is attached to a computer main body, and based on a result of the detection, determines whether or not the extension unit is attached to the computer.
0, the frequency of the clock signal for operating each unit of the computer is increased or decreased.
-Operate by the DC converter 15 to store the memories 3a, 3b
Use one of them. On the other hand, when attached to the extension unit, the computer main body is connected to the DC-D on the extension unit side.
Operated by a C converter, and both memories 3a and 3b are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a computer and a computer system to which an expansion unit for expanding functions can be mounted.

[0002]

2. Description of the Related Art Laptop type or notebook type portable computers which are easy to carry and can be operated by a battery have been developed. In this type of portable computer, an expansion unit for expanding functions can be mounted as needed.

The expansion unit includes a drive bay for mounting a drive device such as a hard disk drive,
An expansion slot for installing various option cards is provided. By installing a portable computer in this slot, it is possible to expand functions to the same extent as a desktop computer.

As described above, conventionally, the extension unit has a strong meaning as an option for adding various functions to the portable computer.
A PU, a memory (main storage), a VRAM, a power supply, and the like have been used. Heretofore, these devices have always been set to obtain the highest processing performance regardless of whether or not the portable computer is attached to the extension unit.

[0005] However, with the recent increase in the functions of computers, portable computers have been increasing the processing speed of CPUs, for example, and increasing the capacity of memories and VRAMs. Therefore, it has been difficult to reduce the weight of the portable computer due to an increase in the number of components and the like, and furthermore, the power consumption has increased, and it has been difficult to operate the portable computer with a battery for a long time.

[0006]

As described above, the conventional portable computer has a problem that it is difficult to reduce the size and weight, which is originally required for the portable computer, and it is also difficult to operate the portable computer for a long time by using a battery. there were.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a computer and a computer system which can reduce the size and weight of a computer main body and which can be operated by a battery for a long time when being carried.

[0008]

In order to solve the above-mentioned problems, a computer according to the present invention is a computer in which an expansion unit for expanding functions is detachably attached to a computer main body. Detection means for detecting the presence or absence of a unit, and control for increasing or decreasing the frequency of a clock signal for operating the computer body according to the presence or absence of the extension unit with respect to the computer body based on the detection result of the detection means Means.

In this case, when the computer main body is not mounted on the extension unit, the processing speed of the computer main body is reduced, and accordingly the power consumption is reduced, so that the operation time by the battery becomes longer.

According to the present invention, there is provided a computer having a second power supply unit and a detachably attachable expansion unit for expanding functions to a computer main unit having a first power supply unit. Detecting means for detecting whether or not the unit is mounted; and, based on the detection result of the detecting means, determining whether or not the expansion unit is mounted on the computer main body. Power supply switching means for supplying power to the computer main body from the power supply device and for supplying power from the first power supply device to the computer main body when the extension unit is not attached to the computer main body may be provided.

With this configuration, the first power supply device provided in the computer main body is used only when the computer main body is not mounted on the extension unit.
At this time, a small and lightweight one can be used according to a desired operation time.

According to the present invention, there is provided a computer in which an expansion unit for expanding the functions of the computer main body can be detachably attached to the computer main body having the first and second memories. Detecting means for detecting the presence or absence of wearing;
Based on the detection result of the detecting means, the first and second memories are operated together when the extension unit is attached to the computer main body, and the first and second memories are operated when the extension unit is not attached to the computer main body. And control means for controlling only one of the second memories to operate.

In this case, when the computer body is not mounted on the expansion unit, only one of the first and second memories is operated, so that the power consumption is reduced and the operation time by the battery is extended. Can be.

Further, the present invention relates to a computer having an extended memory and capable of detachably attaching an extension unit for extending the function of the computer body to a computer body having a memory. Detecting means for detecting the presence or absence of
Based on the detection result of the detection means, when the extension unit is attached to the computer body, the memory of the computer body and the extension memory of the extension unit are operated together, and when the extension unit is not attached to the computer body, And control means for controlling only the memory of the computer main body to operate.

With this configuration, the memory of the computer main body can have a necessary minimum capacity according to a desired processing function when the computer is operated alone. Therefore, the memory itself can be reduced in size and weight, and the power consumption can be reduced, so that the operation time by the battery can be extended. Note that each of these inventions can also be configured as a computer system including a computer and an extension unit.

[0016]

FIG. 1 is a block diagram showing a configuration of a personal computer according to an embodiment of the present invention. This personal computer is a notebook-type or laptop-type portable computer which can be operated by a battery, and is detachably attached to the docking station shown in FIG. Hereinafter, the time when the personal computer is mounted on the docking station is referred to as mounting time, and the time when the personal computer is not mounted on the docking station is referred to as non-mounting time.

The personal computer comprises a CPU 1 and
Memory bus switch 2, memories 3a and 3b, PCI
Bridge 4, BIOSROM 5, hard disk drive (hereinafter, HDD) 6, display controller 7, VRAM 8, LCD (liquid crystal display) 9
, Clock control unit 10 and docking I / F 1
1, a power supply switching unit 14, a DC-DC converter 15, a battery 16, and a PCI-DS bridge 17. This personal computer is provided with a docking connector 18 through which it is connected to the docking station shown in FIG.

The CPU 1 is, for example, a microprocessor "Pentiu" manufactured and sold by Intel Corporation.
m "and the like, and are connected to the memory bus switch 2 and the PCI bridge 4 via a memory bus 23 having a 64-bit data bus.

The memory bus switch 2 controls the memories 3a, 3a for the memory bus 23 in accordance with the presence or absence of the connection of the docking station to the personal computer.
b and for switching the connection state of the extended memory 30 in FIG. The memory bus 23 is guided to the outside of the personal computer through the memory bus switch 2, and when mounted, the docking connector 18
Is connected to the external memory bus 41 of the docking station via the connector section 19 of the docking station.

The memories 3a and 3b are memory devices for storing an operating system, a device driver, an application program to be executed, processing data, and the like, and each is constituted by a DRAM module.

The memory 3a is always used regardless of whether or not the docking station is attached to the personal computer.
Only used. Therefore, a memory (for example, 8 Mbytes) having a capacity corresponding to a desired minimum processing performance is provided as the memory 3a.

On the other hand, the memory 3b is used only at the time of mounting. Therefore, as the memory 3b, the memory 3
A device having a capacity corresponding to the processing performance desired when used with a is installed. The control of use / non-use of the memory 3b is performed by increasing / decreasing the memory area available on the system and further turning on / off the power supply to the memory 3b.

Further, as will be described later, at the time of mounting, the extension memory 30 of the docking station is used together with the memory 3a. Therefore, if priority is given to miniaturization and weight reduction of the personal computer, it is not always necessary to provide the memory 3b.

The PCI bridge 4 is connected to the memory bus 23 and the P
CI (Peripheral Component I)
a bridge LSI for connecting a bus cycle including data and addresses between the memory bus 23 and the PCI bus 24 in a bi-directional manner; a memory 3a, 3b and an extended memory Access control to the memory 3a when not mounted.
It has a function of controlling access to the device.

The PCI bus 24 has a BIOS ROM 5,
HDD 6, display controller 7, clock control unit 10, docking I / F 11, and PCI-D
The S bridge 17 is connected. Further, the PCI bus 24 connects the PCI bridge 17 to the docking connector 18.
Is connected to the external PCI bus 36 of the docking station via the connector unit 20 of the docking station.

The BIOS ROM 5 stores a BIOS (Basic
c I / O System), and is constituted by a flash memory so that a program can be rewritten. The BIOS stores a system management program and device drivers for controlling various I / O devices.

The HDD 6 stores data such as an OS, various applications, and document files. Further, the HDD 6 is used to save the data in the operating memories 3a and 3b and the extended memory 30 in order to prevent the system from hanging up when the personal computer is removed from the docking station. Note that the data saved in the HDD 6 is appropriately read and used in the memory 3a that operates when not mounted, similarly to the normal virtual storage processing.

The display controller 7 is one of the bus masters of the PCI bus 24, like the PCI bridge 4, and is used for displaying the image data sent from the CPU 1 to the VRAM 8 on the LCD 9.

The clock control unit 10 controls a clock signal for operating each unit in the personal computer (including each unit in the docking station when mounted). Specifically, the clock control unit 10 corresponds to whether or not the docking station is attached to the personal computer,
For example, the frequency of a CPU clock for operating the CPU 1, the frequency of a memory clock for operating the memory 3a (the memories 3a and 3b and the extended memory 30 when mounted), the PCI bus 24 (the external PCI bus 3 when mounted).
6) and the frequency of the PCI bus clock that determines the cycle above is increased or decreased.

The frequency of each of these clock signals is set so that the personal computer exhibits the highest processing performance when mounted (for example, CPU clock 233 MH).
z, the PCI bus clock is 33 MHz), and is set so that the desired minimum processing performance is realized when not mounted (for example, the CPU clock is 100 MHz, the PCI bus clock is 30 MHz).

The docking I / F 11 is a communication unit provided for communication between the personal computer and the docking station.
Is connected to the docking station via the connector section 21 of.

The docking I / F 11 includes an attachment / detachment detection unit 12, and the attachment / detachment between the personal computer and the docking station by the attachment / detachment detection unit 12 (hereinafter referred to as docking / ejecting).
, And notifies it to the CPU 1 by SMI (system management interrupt), and further outputs a predetermined power switching signal to the power switching unit 14. However, regarding the ejection, in order to prevent the system from hanging up, it is detected not when the personal computer is actually ejected from the docking station but when the user makes an ejection request.

The docking I / F 11 performs control so that when the personal computer is docked in the docking station while the power is on, the expansion device is not destroyed due to hot swapping or the like and malfunction of the system does not occur.

The power supply switching unit 14 is for switching the power supply of the personal computer according to whether or not the docking station is attached to the personal computer. That is, the power supply switching unit 1
4 operates the DC-DC converter 15 in the personal computer when not mounted and operates the DC-DC converter 32 in the docking station when mounted, based on the power supply switching signal input from the docking I / F 11.

The DC-DC converter 15 is used as a power supply for a personal computer when not mounted, and distributes power supplied from the battery 16 to each unit in the personal computer. As described above, it is not necessary to supply power to the memory 3b when not mounted, and the frequency of the clock signal for operating each unit is reduced by the clock control unit 10, so that the power consumption is reduced as compared to when mounted. . Therefore, the DC-DC converter 15 may have a lower capacity (for example, 20 W) than the DC-DC converter 32 of the docking station.

The PCI-DS bridge 17 is a bridge LSI for connecting the PCI bus 24 and an external PCI bus 36 of the docking station, and is connected to the docking station via the connector section 20 of the docking connector 18.

Next, a docking station to which such a personal computer is detachably mounted will be described with reference to FIG. The docking station is an extension unit for extending the functions of a personal computer, and includes an extension memory 30, a DS-PCI
Bridge 31, DC-DC converter 32, docking station controller (hereinafter, DS controller)
33, EEPROM 34, card controller 35, P
It has a CI expansion slot 42 and a PC card slot 43, and is provided with a docking connector 36 for connecting to a personal computer. The docking connector 36 has connector portions 37 to 40, which correspond to the connector portions 19 to 22 of the docking connector 18 of the personal computer.

When the extension memory 30 is mounted, the memory 3a,
The memory 3a is used together with the main memory 3b as a main memory of the personal computer, and is composed of several DRAM modules like the memories 3a and 3b.

This extended memory 30 is connected to the external memory bus 4
1 and connected to the connector 37 at the time of mounting, and is connected to the memory bus 23 of the personal computer via the connector 37 and the connector 19 of the personal computer. Therefore, the external memory bus 41 needs to have the same bus width as the memory bus 23.

The DS-PCI bridge 31 is a bridge LSI that connects the PCI bus 24 guided to the docking station via the connector 38 at the time of mounting and the external PCI bus 36. On the external PCI bus 36, a PCI expansion slot 42 for mounting various expansion boards,
A card controller 35 for controlling a PC card mounted in the C card slot 43 is provided.
The external PCI bus 36 is set to the same bus width as the PCI bus 24.

The DS controller 33 controls the attachment / detachment between the personal computer and the docking station, and communicates with the docking I / F 11 of the personal computer via the connector 39.
In particular, when an eject request is made by the user at the time of mounting by operating an eject switch, which will be described later, the fact is notified to the docking I / F 11 and the SMI is notified.
Prompts the output of the signal and the power supply switching signal. At this time,
For example, when communication between the personal computer and the docking station is being executed and it cannot be interrupted, the DS controller 33 may reject the eject request. The DS controller 33 also controls on / off of a DC-DC converter 32 which is a power supply device provided in the docking station.

The EEPROM 34 is for storing PnP information necessary for plug and play, such as attributes (for example, addresses and DMA channels) of expansion boards and the like installed in the PCI expansion slot 42.
This PnP information is transmitted when the personal computer is attached to the docking station or when the personal computer or the docking station is powered on.
It is read into the personal computer under the control of the program in the BIOS ROM 5.

The DC-DC converter 32 is used as a power supply for a personal computer instead of the DC-DC converter 15 of the personal computer when the personal computer is mounted. To each unit. Here, when the personal computer is mounted, the personal computer is operated with the highest processing performance, so that the power consumption in the personal computer also increases. Therefore, DC-DC
As the converter 32, a personal computer D
The C-DC converter 15, that is, the one having a larger capacity (for example, 40 W) than the power supply device when not mounted is used.

FIGS. 3A and 3B are views showing the appearance of such a docking station. FIG. 3A is a front view, and FIG. 3B is a perspective view showing a state in which a personal computer is mounted.

The housing of the docking station 200 is provided with a mounting surface 60 for accommodating the personal computer 100. The mounting surface 60 is formed to have substantially the same size as the bottom surface of the main body of the personal computer 100, and has guide portions 67 at both left and right end portions for introducing the personal computer 100 to the mounting position.

At the rear end of the guide section 67, a guide pin 61 for securely mounting the personal computer 100 is provided. When the personal computer 100 is mounted and the docking connector 55 is connected, the guide pins 61 protrude from the guide portion 67 and are inserted into holes in the bottom surface of the main body of the personal computer 1. When it is ejected, it is pushed down so as to be pulled out of the hole.

The docking station is also provided with an eject switch 63, a power indicator 64, a drive-in use indicator 65, a docking indicator 66, and the like.

The eject switch 63 is a switch for detaching the personal computer 100 from the docking station 200. For example, in response to the operation of the eject switch, an ejection request is issued from the DS controller 33 to the docking I / F 11. Notified.

The power indicator 64 lights up when the docking station is powered on, and the live-in use indicator 65 lights up when the internal hard disk drive or the like is being accessed. Further, the docking indicator 66 starts blinking when the personal computer 1 is set at the mounting position, and continuously lights when the mounting of the personal computer 1 is completed.

Next, the processing when the personal computer and the docking station are attached and detached will be described with reference to FIG. This processing is performed by the docking I / F 11
The SMI processing corresponding to the detection of the attachment / detachment between the personal computer and the docking station by the attachment / detachment detection unit 12 is performed.

In this case, first, it is determined whether the cause of the SMI, that is, whether the user's request for attachment / detachment is for docking the personal computer to the docking station or for ejecting the personal computer from the docking station (step S1). . The cause of the occurrence of the SMI is determined by, for example, the on / off state of the eject switch 63 shown in FIG.

When the docking is determined in step S1, it means that the personal computer is mounted on the docking station. At this time, the docking connector 18 of the personal computer and the docking connector 36 of the docking station are connected in terms of hardware, and the memory bus 23 and the external memory bus 41, the PCI bus 24 and the external PCI bus 36, and the docking I / F 11 are connected. The DS controller 33, the power supply switching unit 14, and the DC-DC converter 32 are connected respectively.

In this case, first, the memory 3b and the extended memory 30 are connected to the memory bus 23 by the memory bus switch 2, and setting is made to increase the memory area usable on the system. Step S2).

Next, each clock signal for operating each unit in the personal computer and the docking station is set to the highest frequency, that is, the highest speed by the clock control unit 10 (step S).
3).

Further, a power supply for operating the personal computer by the power supply switching unit 14 is changed from the DC-DC converter 15 in the personal computer to the DC-DC converter 32 in the docking station.
Is switched to (step S4).

By doing so, the processing speed of each unit in the personal computer is increased, and the available memory capacity is also increased, so that the personal computer can be operated at the desired maximum processing performance. In this case, the power consumption of the personal computer also increases.
Since the personal computer is operated by the power supplied from the AC adapter using the C-DC converter 32, the power of the battery 16 does not need to be consumed.

On the other hand, if the ejection is determined in step S1, it means that the user has issued an ejection request. In this case, the following processing is performed to prevent the system from hanging up, and then the user is permitted to actually eject the system.

More specifically, first, the memories 3a, 3
b and the data in the extended memory 30 are saved in the HDD 6 (step S5), and then the memory 3b and the extended memory 30 are transferred to the memory bus 2 by the memory bus switch 2.
3 and reduce the memory area available on the system (step S6).

Next, the clock control unit 10
Each clock signal for operating each unit in the personal computer is set to a low frequency, that is, a low speed (step S7).

Further, a power supply for operating the personal computer by the power supply switching unit 14 is changed from the DC-DC converter 32 in the docking station to the DC-DC converter 15 in the personal computer.
Is switched to (step S4).

Finally, the user is notified of the ejection permission so that the personal computer can be actually ejected from the docking station (step S9). In this way, the processing speed of each unit of the personal computer can be suppressed, Available memory is also memory 3
Since only a is used, the power consumption of the entire personal computer is reduced, and the personal computer can be operated for a long time even with the battery 16. In addition, since the power consumption is reduced, the personal computer can be sufficiently operated even with the DC-DC converter 15 having a smaller capacity than the DC-DC converter 32.

As described above, in the present embodiment, the processing performance of the personal computer is changed depending on whether or not the docking station is attached to the personal computer.

Specifically, when the personal computer is mounted on the docking station, the frequency of the clock signal for operating the personal computer and each unit in the docking station is increased by the clock control unit 10. The original functions of the personal computer are brought out and an expansion card or the like attached to the docking station can be used, so that the processing can be performed with the highest performance.

In particular, since the extended memory 30 in the docking station is used as the main memory of the personal computer together with the memories 3a and 3b in the personal computer, even if the capacity of the memories 3a and 3b is small, If the capacity is increased, sufficient processing performance can be obtained. Conversely, since the memories 3a and 3b may be of a minimum capacity according to the desired processing performance when not mounted, that is, small and lightweight, the entire personal computer can be reduced in size and weight.

Although the power consumption increases as the processing speed of the personal computer increases, the DC-DC converter 15 in the personal computer when the personal computer is mounted.
Instead, the DC-DC converter 32 in the docking station is used as a power supply, and power is obtained from an AC adapter connected to the docking station, so that the battery 16 in the personal computer is not consumed.

On the other hand, when the personal computer is not mounted on the docking station, the frequency of the clock signal for operating each unit in the personal computer is reduced by the clock control unit 10, so that the processing speed of the entire personal computer is reduced. And power consumption is reduced as a whole. In particular, since power supply to the bulk memory 3b is interrupted and only the memory 3a is used, power consumption in the memory portion can be further reduced. As a result, the power saving effect of the personal computer is enhanced, and the personal computer can be operated for a long time using only the battery 16.

At this time, the DC-DC converter 15 is used as a power supply device of the personal computer. However, since the power consumption of the entire personal computer is suppressed, the DC-DC converter 15 is limited. Since it is sufficient to install a small capacity and a light weight that can cover the power consumption, the whole personal computer can be reduced in size and weight.

[0068]

As described above, according to the present invention, when the computer main body is not mounted on the expansion unit, the processing speed of the computer main body is reduced, so that the power consumption is reduced, and the computer is operated by the battery. Can be operated for a long time.

Further, the first power supply device in the computer main body is used only when the computer is operated alone, so that the first power supply device can be small and lightweight according to a desired operation time.

If the computer has the first and second memories, when the computer is not mounted on the expansion unit, only one of the first and second memories is operated to reduce the power consumption. Therefore, the operation time by the battery is prolonged.

Furthermore, if the extension unit has an extension memory, the memory of the computer body is used together with the memory of the extension unit when the computer is mounted on the extension unit. A memory having a minimum necessary capacity is sufficient, the memory itself can be reduced in size and weight, and power consumption can be further reduced.

[Brief description of the drawings]

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

FIG. 2 is an exemplary block diagram illustrating a configuration of a docking station to which the personal computer according to the embodiment is mounted.

FIG. 3 is a view showing the appearance of the docking station shown in FIG. 2;

FIG. 4 is an exemplary flowchart for explaining processing when the personal computer and the docking station of the embodiment are attached and detached;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... CPU 2 ... Memory bus switch 3a, 3b ... Memory 4 ... PCI bridge 5 ... BIOSROM 6 ... Hard disk drive 7 ... Display controller 8 ... VRAM 9 ... LCD 10 ... Clock control unit 11 ... Docking I / F 12 ... Removal detection unit DESCRIPTION OF SYMBOLS 14 ... Power supply switching unit 15 ... DC-DC converter 16 ... Battery 17 ... PCI-DS bridge 18 ... Docking connector 19, 20, 21, 22 ... Connector part 23 ... Memory bus 24 ... PCI bus

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G06F 12/06 515 G06F 1/04 320A

Claims (8)

[Claims] 1. A computer in which an expansion unit for expanding a function is detachably attached to a computer main body, wherein a detection means for detecting whether or not the expansion unit is mounted on the computer main body; A computer, comprising: control means for performing control to increase or decrease the frequency of a clock signal for operating the computer main body according to whether or not the extension unit is attached to the computer main body based on the detection result. 2. A computer having a second power supply to a computer main body having a first power supply and capable of detachably mounting an expansion unit for expanding functions of the computer main body. Detecting means for detecting whether or not the extension unit is mounted on the main body; and mounting the expansion unit on the computer main body in accordance with whether or not the expansion unit is mounted on the computer main body based on a detection result of the detection means. Power is supplied from the second power supply device to the computer main body, and power is supplied from the first power supply device to the computer main body when the extension unit is not attached to the computer main body. And a power supply switching unit. 3. A computer in which an expansion unit for expanding functions can be detachably attached to a computer main body having first and second memories, wherein the presence / absence of attachment of the extension unit to the computer main body is detected. Based on the detection result of the detection means, when the extension unit is attached to the computer main body, the first and second memories are operated together, and the extension unit is provided to the computer main body. And control means for controlling only one of the first memory and the second memory when the memory is not mounted. 4. A computer having an extended memory to a computer main body having a memory and capable of detachably mounting an expansion unit for expanding the function of the computer main body, wherein the expansion unit is mounted on the computer main body. Detecting means for detecting the presence or absence of, based on the detection result of the detecting means, when the expansion unit is mounted to the computer main body, the memory of the computer main body and the expansion memory of the expansion unit are operated together, Control means for controlling only the memory of the computer main body when the extension unit is not attached to the computer main body. 5. A computer system comprising a computer and an extension unit detachably attached to the computer to extend the functions of the computer, wherein a detection means for detecting whether or not the extension unit is attached to the computer. And control means for performing control to increase or decrease the frequency of a clock signal for operating the computer in accordance with the presence or absence of the extension unit on the computer based on the detection result of the detection means. Computer system. 6. A computer having a first power supply,
In a computer system including an extension unit detachably attached to the computer to extend the function of the computer, the computer system having a second power supply device, a detection unit for detecting whether the extension unit is attached to the computer. Based on the detection result of the detection means, depending on whether the extension unit is attached to the computer or not, when the extension unit is attached to the computer, power is supplied from the second power supply device to the computer. And a power supply switching means for supplying power from the first power supply device to the computer when the extension unit is not mounted on the computer. 7. A computer system comprising: a computer having first and second memories; and an extension unit detachably mounted on the computer to extend the functions of the computer, wherein the extension unit is provided for the computer. Detecting means for detecting the presence / absence of attachment; based on a detection result of the detecting means, when the extension unit is attached to the computer, the first
And control means for operating both the first and second memories when the expansion unit is not attached to the computer by operating both the first and second memories. A computer system characterized by the above-mentioned. 8. A computer system comprising: a computer having a memory; and an extension unit having an extension memory and detachably attached to the computer in order to extend the function of the computer. Detecting means for detecting the presence / absence of attachment; based on the detection result of the detecting means, when the extension unit is attached to the computer, operates both the memory of the computer and the extension memory of the extension unit; A computer system comprising: control means for performing control for operating only the memory of the computer when the extension unit is not attached to the computer.