GB2240643A

GB2240643A - Magnetic disc apparatus with dual control programs

Info

Publication number: GB2240643A
Application number: GB9100250A
Authority: GB
Inventors: Masayuki Urabe
Original assignee: Tokico Ltd
Current assignee: Tokico Ltd
Priority date: 1990-01-19
Filing date: 1991-01-07
Publication date: 1991-08-07
Also published as: JPH03214225A; DE4101424A1; GB9100250D0

Abstract

The present invention discloses a magnetic disk storage apparatus suitable for being connected to a host computer and for being used as a storage apparatus for the host computer. There is provided a magnetic disk storage apparatus being composed of memory 10, (13 Fig 5) for storing a first control program for supporting SCSI, the Small Computer System Interface, and a second control program for supporting SASI, the Shugart Associates System Interface; a switch 11 for selecting either of the first control program and the second control program; and a controller for processing data based on the control program selected by the switch. <IMAGE>

Description

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MAGNETIC DISK STORAGE APPARATUS Background of the Invention [Field of the Invention]

The present invention relates to magnetic disk drive devices. and In particular. to magnetic disk drive devices incorporating integral disk controller circuitry.

[Prior Art]

Recently, various types of intelligent magnetic disk drive devices employing integral disk controller circuitry have become available. Among these are disk drives incorporating the SCSI (Small Computer System Interface) standard, and the predecessor of the SCSI standard, the SASI (Shugart Associates System Interface) standard.

By providing the disk controller as an integral component of the disk drive device, the processing load on the host computer can be reduced and overall system throughput can be increased. Additionally, the SCSI interfaces makes it possible to daisy-chain multiple SCSI devices on a single external 1/0 bus and to carry out simultaneous data 1/0 on two or more such daisy-chained devices, Including SCSI devices other than magnetic disk drives. Many of capabilities of the SCSI standard were offered by the preceding SASI specification. Fig.1 is a block diagram of a small computer system employing such a conventional disk drive device.

Seen in this diagram is a host computer 1 and an 1 external bus 3 on which multiple disk drive devices 2 are connected.

Each disk drive devices 2 in turn made up of a CPU 4 for controlling the various other components of the disk drive device 2. ROM 5 for storing data and control programs utilized by CPU 4. RAM 6. a disk drive circuit 7 for operating mechanical disk drive components, an interface 8 connecting host computer 1 and CPU 4. and an internal bus 9 for connecting CPU 4 and each component of the disk drive device 2.

In the above disk drive device 2, the above Interface 8 is the interface for the SCSI device or the interface for the SASI device. Although in the above description each disk drive device 2 contains interface 8, host computer 1 may contain interface 8 instead; the location of interface 8 is not crucial.

In this case, in a magnetic disk disk drive device supporting SCSI, software only for SCSI is stored in ROM (ROM 5) of having a storage capacity of 32 Kilobytes. On the other hand, in a magnetic disk drive device supporting SASI, software only for SASI is stored in ROM (ROM 5) having the same storage capacity as the former.

Thus. there is no difference in hardware between the disk drive device supporting SCSI and the disk drive device supporting SASI.

However. in the above mentioned_ conventional disk drive device, because a desired type of software. that is, a desired type of ROM, is selected corresponding to the type of interface which is supported thereby. manufacturers must make 2 I.

1 troublesome production decisions with regard to SCSI the standard and the SASI standard.

In addition, device setup is very complicated for users because the type of disk drive device for a host computer employing or supporting SCSI Is different from the type of disk drive device for a host computer employing or supporting SASI.

Summary of the Invention

1 In view of the above-described problem, it is an object of the present invention to provide a magnetic disk drive device which is capable of reducing the burdens on manufacturers and users with regard to production and installation in spite of the fact that two standards are in existence.

In an aspect of the present invention, there is provided a magnetic disk storage apparatus (2) suitable for being connected to a host computer (1) and for being used as a storage apparatus for said host computer (1), said magnetic disk storage apparatus (1) characterized by comprising:

(a) memory (10, 13) for storing a first control program for supporting SCSI, the Small Computer System Interface. and a second control program for supporting SASI, the Shugart Associates System Interface; (b) selecting means (11) for selecting either of said first control program and said second control program; and (c) a controller (4) for processing data based on the control program selected by said selecting means (11).

3 Therefore, the present invention can achieve reducing the burdens on manufacturers and users with regard to production and 1nstallation In spite of the fact that two standards are in existence Brief Description of the Drawings

Fig. 1 Is a block diagram of a small computer system employing a conventional magnetic disk drive device.

Fig. 2 is a circuit diagram showing a connection between a ROM and a hard switch which are used in the magnetic disk drive device according to the first embodiment of the present invention.

Fig. 3 is a schematic view showing the conceptual construction of memory area in the same ROM.

Fig. 4 Is a block diagram showing a support change-over circuit which is employed in the magnetic disk storage according to the second embodiment of the present invention.

Fig. 5 is a schematic view showing a conceptual construction of memory area in a ROM which is used in the magnetic disk drive device according to the same embodiment.

Fig. 6 is a flow chart showing SCSI/SASI support change over processing procedure as an operation of the magnetic disk storage apparatus according to the second embodiment.

Detailed Description of the Preferred Embodiments [A] FIRST PREFERRED 04BODIMENT In the following section, the first preferred embodiment 4 r 1 1 of the present Invention will be described with reference to Figs. 2 and 3.

The main differences between the disk drive device according to this embodiment and the above conventional disk drive device shown in Fig. 1 are that. Instead of the conventional 32 kB ROM IC chip. 64 kB ROM IC chip is employed therein so as to store a control program supporting both SCSI and SASI in the disk drive device according to this embodiment, and that a hard switch for changing from one type of interface to the other therein.

Fig. 2 is a circuit diagram showing a connection between the above mentioned ROM and the hard switch which are used in the disk drive device according to the first embodiment. In this figure, a reference number 10 indicates ROM IC chip having a storage capacity of 64 Kilobytes. Reference number 11 indicates a hard switch, for example a dip switch. As shown in Fig. 3, in the above ROM 10, a control program for SAS! is stored in memory area 10A which are present between address [00001 and address [7FFF1 corresponding to a storage capacity of the first 32 Kilobytes. And a control program for SCSI is stored In memory area 10B which are present between address [8000] and address [FFFF] corresponding to the rest of a storage capacity.

Next. one terminal 11A of the above hard switch 11 is connected to both a power supply via a resistor 12 and to either memory area 11A or memory area 11B. Another terminal 11B of hard switch 11 is grounded. In this embodiment, one terminal 11A is connected to the memory area A15 of the address number 15. Thus, if terminal 11A and terminal 11B are connected. data read out from ROM 10 at address corresponding to memory area 15 is [01. Also. if terminal 11A and terminal 11B are not connected. data read out from ROM 10 at address corresponding to memory area 15 is [11.

Here, CPU 14 is installed based on the control program for SASI, when memory area A15 is set to [01, and also based on the control program for SCSI, when memory area A15 is set to [11.

With the above mentioned construction. because the disk drive devices has the interface functions of both SCSI and SASI, management is simplified.

Additionally, It is easier for users to set up a disk drive device. because the disk drive device can be connected both to a host computer employing or supporting SCSI and to a host computer employing or supporting SASI.

[B] SECOND PREFERRED EMBODIMENT In the following section. the second preferred embodiment of the present invention will be described with reference to Figs. 4 to 6.

Fig. 4 is a block diagram showing a support change-over circuit which is employed in the disk drive device according to the present invention.

As clearly shown in this figure, the main difference between the disk drive device according to this second embodiment and that of the first embodiment is that CPU 4 Is inserted between a hard switch 11 and ROM 13 in the disk drive device according to this second embodiment.

6 1 r 4 1 i Fig. 5 is a schematic view showing a conceptual construction of memory area In a ROM which is used in a disk drive device according to this second embodiment.

As shown obviously in this figure, memory area 13A which are present between address [0000] and address [7FFF1 corresponding to a storage capacity of the first 32 Kilobytes, is assigned to a control program for supporting SASI. Memory area 10B which are present address [8000] and address [FFFF], corresponding to the rest of a storage capacity, is assigned to a control program for supporting SCSI. These assignments are similar to those in ROM 10 shown in Fig. 3. However. ROM 13 shown in Fig. 5 differs from ROM 10 in that the processing program, which is the minimum series of Instructions necessary for the operation of CPU 4, and the program for checking setting state [0/11 of hard switch 11, are similarly stored at the head portions Ca and Cb of memory areas 13A and 13B.

Next. SCSI/SASI support change-over processing procedure will be described according to the second embodiment as described above, with reference to the flow chart shown in Fig. 6.

If power has already been supplied to CPU 4. CPU 4 Is In operation. First, in step SP1. CPU 4 checks the input state from hard switch 11. As the result of the check, when CPU 4 judges that the Input state from hard switch 11 is [11. that is. when the potential state between both terminals 11A and 11B is open state. CPU 4 goes to step SP2, and therein stores [11 in memory area A15 of ROM 13. When memory area A15 is 7 set to [11, CPU 4 executes processing hereinafter, according to the control program for SCSI.

On the other hand, As the result of the cheek in step SP 1, when CPU 4 judges that the input state from hard switch 11 is [01. that Is, when the potential state between both terminals 11A and 11B is short state. CPU 4 goes to step SP3. and therein stores [01 in memory area A15 of ROM 13. When memory area A15 is set to [01. CPU 4 executes processing hereinafter. according to the control program for SASI.

i 11 1 1 i i i i 11 8

Claims

What is claimed is:

1. A magnetic disk storage apparatus (2) suitable for being connected to a host computer (1) and for being used as a storage apparatus for said host computer (1), said magnetic disk storage apparatus (1) characterized by comprising:

(a) memory (10, 13) for storing a first control program for supporting SCSI, the Small Computer System Interface, and a second control program for supporting SASI, the Shugart Associates System Interface; (b) selecting means (11) for selecting either of said first control program and said second control program; and (c) a controller (4) for processing data based on the control program selected by said selecting means (11).

2. A magnetic disk storage apparatus (2) in accordance with claim 1 above characterized in that said selecting means (11) is composed of a hardware switching means (11).

3. A magnetic disk storage apparatus (2) in accordance with claim 1 above characterized in that said selecting means (11) is composed of a software switching means (Ca, Cb).

4. A magnetic disk storage apparatus (2) in accordance with claim 1 above characterized in that said selecting means (11) consists of said hardware switching means (11) and said software switching means (Ca. Cb).

5. A magnetic disk storage apparatus (211 in accordance with claim 1 above characterized in that said memory (10, 13) Is ROM memory (10. 13).

9

6. A magnetic disk storage apparatus (2) in accordance with claim 2 above characterized in that said hardware switching means (11) is a dip switch (11).

7. A magnetic disk storage apparatus (2) in accordance with claim 2 above characterized in that said hardware switching means (11) is physically connected to said memory (10. 13).

8. A magnetic disk storage apparatus (2) in accordance with claim 2 above characterized in that said hardware switching means (11) has two terminals (11A, 11B). one of which is connected to both a power supply via a resistance element (12) and to one of a first memory area (10A, 13M storing said first control program and a second memory area (10B,13B) storing said second control program, and the other terminal is connected to ground; whereby. if said hardware switching means (11) is in a first state, processing based on said SASI control program is carried out, if said hardware switching means (11) is in a second state, processing according to said SCSI control program is carried out.

9. A magnetic disk storage apparatus (2) In accordance with claim 4 above characterized in that said first and second mem6ry areas (10A, 10B, 13A. 13B) both store a processing program, and further store a program for determining the state of said hardware switching means (11). whereby when said controller (4) determines that said hardware switching means (11) is in said first state, processing is carried out based on said SASI control program, 1 i 1 1 1 1 1 i 1 and when said controller (4) determines that said hardware switching means (11) is in said second state, processing is carried out based on said SCSI control program.

10. A magnetic disk storage apparatus substantially as herein described with reference to and as Shown in the accompanying drawings.

11 Published 1991 atThe Patent Office, State House. 66/71 High Holborn. IA)ndonWC I R47?. Further copies may be obtained from Sales Branch. Unit 6. Nine Mile Point, CwMielinfach. Cross Keys. Newport. NPI 7HZ. Printed by Multiplex techniques ltd. St Mary Cray. Kent-