JPH04105147A - External storage device - Google Patents

Abstract

PURPOSE:To reduce the capacity of a RAM by storing the information that is usually used to the read only in a computer system into a ROM and storing other information into the RAM. CONSTITUTION:An input/output part 1 is provided together with a ROM storage part 2, a RAM storage part 3, a ROM/RAM composition information storage part 4, a control part 5, a normal power supply part 6, and a back-up power supply part 7. Then a storage area for the data that are used to the read only in a computer system is defined as a storage area of a ROM with the specific storage of information together with a storage area for other data defined as a storage area of a RAM respectively. In such a constitution, the capacity of the RAM can be reduced and also the capacity of a back-up power supply which holds the storage contents can be reduced.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an external storage device in a computer system.

[Conventional technology]

BACKGROUND ART Magnetic storage devices such as floppy disks, hard disks, and magnetic tapes have been widely used as readable and writable external storage devices in general computer systems. These magnetic storage devices do not require a special power source to retain their stored contents. On the other hand, with recent advances in semiconductor technology, external storage devices using semiconductor storage devices, which are superior to the above-mentioned magnetic storage devices in terms of high speed, resistance to mechanical shock, space saving, etc., are also being used. It is becoming. External storage devices using these semiconductor storage devices include:
There are those using EEFROM and those using RAM. Although EEFROM is rewritable, it typically operates as a read-only device and is not typically used for both read and write applications like magnetic storage devices. On the other hand, RAM is generally capable of both reading and writing, and is therefore used instead of magnetic storage devices. As a readable and writable external storage device using this RAM, there is a conventional device as shown in FIG. This external storage device includes an input/output section 31 that is an interface section with the computer, and a storage section R that is composed of a RAM.
AM storage unit 32, the input/output unit 31 and RAM
A control section 33 that controls the storage section 32, a normal power supply section 34 that normally supplies power to the input/output section 31, the RAM storage section 32, and the control section 33, and a normal power supply section 34 that controls the RAM storage when the normal power supply section 34 is off. A backup power supply section 35 is configured to maintain the storage contents of the section 32. and,
The entire storage area of the RAM storage unit 32 is determined as a read-only area or a read/write-only area, and the control unit 33 receives logical storage area designation information (hereinafter referred to as a logical address) from the computer. (hereinafter referred to as a physical address) is converted into physical storage area designation information (hereinafter referred to as a physical address) to access the RAM storage unit 32.

[Problem to be solved by the invention]

By the way, as mentioned above, external storage devices using semiconductors are superior to external storage devices using magnetic storage devices in terms of high speed, mechanical shock resistance, space saving, and power saving. However, if the storage device is composed only of RAM, it is relatively expensive. Furthermore, as shown in the conventional example in Fig. 3, a storage device configured only with this RAM requires a backup power supply to maintain the memory contents, and moreover, it is necessary to maintain all the memory contents, so a backup The disadvantage is that the capacity of the power supply becomes large. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an external storage device using a semiconductor that is inexpensive and does not require a large capacity backup power source.

[Means to solve the problem]

In order to achieve the above object, the present invention provides an external storage device for a computer system, which includes a storage section composed of a ROM and a RAM, and a logical address of the ROM and the RAM used in the computer system. Refers to the storage area designation information storage means that stores the storage area designation information in association with the address, and receives the logical address sent from the computer, and converts the logical address into a physical address. , accesses the storage area of the ROM or RAM indicated by the physical address,
The device is characterized in that it includes a control section that reads or writes data.

[Effect]

In the above configuration, the control unit receives a logical address sent from the computer, refers to the storage area designation information storage means, converts the logical address into a physical address,
The storage area of the ROM or RAM indicated by the physical address is accessed to read or write data. ROM does not require a power supply to retain its stored contents, whereas RAM requires a power supply to retain its stored contents. Therefore, the storage area designation information storage means stores information such that the storage area for data that is used only for reading in the computer system is the ROM storage area, and the storage area for other data is the RAM storage area. By keeping RA
The storage capacity of M can be reduced, and therefore the capacity of the backup power source for retaining the storage contents can be reduced.

【Example】

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments. FIG. 1 is a block diagram showing an embodiment of an external storage device of the present invention. In FIG. 1, l is an input/output section that is an interface with a computer (not shown), 2 is a ROM storage section that is a read-only memory made up of ROM, and 3 is a read/write-only memory that is made up of RAM. This is a RAM storage unit. Further, 4 is a ROM/RAM organization information storage unit that organizes and stores the physical addresses of the ROM storage unit 2 and the physical addresses of the RAM storage unit 3 in association with logical addresses used in the computer system; 5
is the control section. The control section 5 receives a logical address sent from the computer via the input/output section 1, refers to the ROM/RAM 1i configuration information storage section 4, and converts the logical address into a physical address. Then, the ROM storage unit 2 represented by the physical address obtained by the conversion
Or access the storage area of the RAM storage unit 3,
Reading data from the ROM storage unit 2, reading the data from the RA
Reading data from the M storage unit 3 or the above RAM
Controls writing of data to the storage unit 3. 6 is the input/output section 1.6 during normal operation. A normal power supply unit 7 that supplies power to the ROM storage unit 2, RAM storage unit 3, and control unit 5 supplies power to the RAM storage unit 3 when the normal power supply unit 6 is off, and operates the RAM storage unit 3. This is a backup power supply unit that maintains memory contents. The storage area of the ROM storage 112 and the RAM storage section 3
By appropriately combining the storage areas of , according to the organization information stored in the ROM/RAM organization information storage section 4,
Depending on the usage status of the applied computer system, its file system, and application software, the storage area for data that is normally used only for reading is allocated to the ROM storage unit 2, which does not require power backup, and the storage area for other data is allocated. R that requires power backup
By allocating it to the AM storage section 3, the capacity of the RAM can be reduced, and therefore the capacity of the backup power supply can be reduced. This allows computer systems that are built on the premise of conventional recording media (magnetic storage devices) that do not require power backup, to be able to operate without compromising their configuration.
It can be constructed using a +1 storage device other than this embodiment, which minimizes the power required for backup. For example, if the external storage device of this embodiment is used as an external storage device for starting up a computer system, information that is used only for normal reading of the system main body, etc. of the system software is stored in the ROM storage section 2. files that contain information that defines the system startup status are RA
It is stored in the lvl storage unit 3. As a result, the startup status can be changed by rewriting the relevant file according to the usage status, and furthermore, the ROM storage unit 2 composed of ROM does not require power backup. FIG. 2 is a flowchart showing the operation of this embodiment. When the logical address is sent from the computer, the control unit 5 reads the logical address in step S+, refers to the ROM/RAM organization information storage unit 4 in step S2,
Convert that logical address to a physical address. and,
In step S3, it is determined whether the request from the computer is for reading or writing. If it is a read request, the process proceeds to step S4; otherwise, the process proceeds to step S5. Step S
4, the RO represented by the physical address obtained by the above conversion is
The storage area of the M storage unit 2 or the storage area of the RAM storage unit 3 is accessed to read data, and the read data is transmitted to the computer. In step S5, it is determined whether the storage area indicated by the physical address is the RAM storage unit 3, and
Since data can be written to the storage unit 3,
Proceeding to step S6, data from the computer is written into the storage area indicated by the physical address. On the other hand, if there is no RAM storage unit 2, data cannot be written, so the process advances to step s7 and error processing is performed. In this way, the external storage device of this embodiment has a storage section composed of a ROM storage section 2 that does not require a power source to hold stored contents, and a RAM storage section 3 that requires a power source to hold stored contents. By storing information that is normally used only for reading in a computer system in the ROM storage unit 2 and storing other information in the RAM storage unit 3,
RAM capacity can be reduced. Therefore, the capacity of the backup power supply section 7 can be reduced compared to the conventional example in which the storage section is composed of only RAM, and the cost of the entire device can be reduced.

【Effect of the invention】

As is clear from the above, the external storage device of the present invention is
a storage unit composed of a ROM and a RAM; a storage area designation information storage means for storing physical addresses of the ROM and the RAM in association with logical addresses used in the computer system; In response to the received logical address, the storage area designation information storage means is referred to, the logical address is converted to a physical address, and the storage area of the ROM or RAM represented by the physical address is accessed to read data or Since the computer system is equipped with a control unit that performs writing, the capacity of the RAM can be reduced by storing information that is normally used only for reading in the computer system in the ROM, and storing other information in the RAM. Therefore, compared to the conventional example in which the storage section is composed of only RAM, the capacity of the backup power supply required to retain the storage contents can be reduced, and the cost can be reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the external storage device of the present invention, FIG. 2 is a flowchart showing the processing contents of the above embodiment, and FIG. 3 is a block diagram of a conventional example. l...Input/output unit, 2...ROM storage unit, 3...RA
M storage unit, 4 ROM/RAM organization information storage unit, 5 control unit, 6
... Normal power supply section, 7... Backup power supply section.

Claims (1)

[Claims] (1) An external storage device in a computer system, which is a storage unit composed of a ROM and a RAM, and a logical storage unit that stores physical storage area designation information of the ROM and the RAM and is used in the computer system. The storage area specification information storage means is stored in association with the area specification information, and the storage area specification information storage means is referred to in response to the logical storage area specification information sent from the computer. a control unit that converts storage area specification information into physical storage area specification information, accesses the storage area of the ROM or RAM represented by the physical storage area specification information, and reads or writes data; An external storage device comprising: