JPH0567047A - Data processor - Google Patents

Abstract

PURPOSE:To reduce a power consumption of the SCSI(small computer system interface) bus terminal resistance in a data processor with built-in a SCSI control circuit. CONSTITUTION:In a data processor 8 with built-in an SCSI bus control circuit 9, a transistor 30 for a switch which separates a feeder line(TERMPWR) for the terminal resistance of the SCSI bus connected at the time of connecting the SCSI bus with an SCSI port connector 10, from an incorporated power source (+5V), and terminal resistances 13 and 14 for the SCSI bus which consume the power of an inside power source at the time of disconnecting the feeder line for the terminal resistance from the inside power source, are incorporated. The resistance value is larger than a specific resistance value decided by an SCSI specification, by one digit. Then, when the SCSI bus is connected, an outside resistance is simultaneously connected with the connector 11 of the SCSI port, and, the synthetic resistance of the resistances 13 and 14 with the outside resistance value to the specific resistance value, or the resistance value close to the specific resistance value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data processing device such as a personal computer having a connection port for a SCSI bus, and more particularly, it is suitable for reducing power consumption when an external device is not connected to the SCSI port. The present invention relates to a data processing device.

[0002]

2. Description of the Related Art FIG. 3 shows an example of the configuration of a conventional SCSI device.
FIG. 4 shows a connection example of the terminating resistor. The built-in SCSI device 3 and the external SCSI devices 4, 5 and 6 are daisy chain connected to the SCSI control device 2 built in the computer main body 1. SCSI standard (ANSI X3.131-19
86) stipulates that a terminating resistor be connected to both ends of the SCSI bus, and that terminating resistor receives power from either device at both ends via the term power (TERMMPWR: power supply line for terminating resistor) line. Wired to be supplied.

The external SCSI devices 4, 5 and 6 cannot be predicted by the device manufacturer side as to which device will be placed at the termination position. There is also a need to facilitate daisy chain connections. Therefore, two external connectors are provided on the same SCSI port,
The terminating resistor 7 is connected to one of the external connection connectors of the SCSI device located at the end.

[0004]

[Problems to be Solved by the Invention] SCSI control LS
Due to high integration and miniaturization of I, the possibility of using the SCSI interface for portable laptop type and notebook type small data processing devices is increasing. In such an application, if the data processing device is configured with the conventional system configuration in mind, the following problems will occur.

In order for a user to freely connect and use a plurality of devices selectable for one data processing device,
Place the data processor at one end of the SCSI bus,
In addition, it is usual that the data processing device has a built-in terminating resistor, and power is supplied to the terminating resistor and the term power line by its own power source. The reason is that the data processor itself has the most power supply in such a system,
In addition, there is no guarantee that the SCSI device selected by the user will always be equipped with a power supply circuit to the terminating resistor. Further, in many cases, not only the SCSI control circuit but also a SCSI device such as a hard disk drive is built in the data processing apparatus main body. Therefore, even if the external device is not connected, S
In order for the CSI bus to operate normally, it is necessary to incorporate a terminating resistor in the data processing device main body and supply power to the terminating resistor with its own power source.

However, it is difficult for a small portable data processing device to have the above configuration in terms of power consumption. There are 18 signal lines that require termination resistors, and the resistance value is S
The CSI standard specifies 330 ohms and 220 ohms. Therefore, when the signal becomes active (LOW), a current of about 9 mA flows through the pair of terminating resistors,
If you try to supply power to the ends on both sides, a maximum of 324
It consumes electric power of mA (1.6 W). Considering that the power consumption of a hard disk drive of 2.5-inch disk diameter type is 2 W to 3 W, the power consumption by this terminating resistor is extremely large, and especially in a small data processing device which is usually driven by a battery, Saving power is an issue.

An object of the present invention is to provide a data processing device for reducing power consumption when a termination resistor for a SCSI bus is incorporated.

[0008]

[Means for Solving the Problems]
In a data processing device having a built-in (Small Computer System Interface) bus control circuit, a means for disconnecting a power supply line for a termination resistor of a SCSI bus, which is connected when a SCSI bus is connected to a SCSI port, from a built-in power source, and the termination. This is a built-in terminating resistor for the SCSI bus that consumes the power of the internal power source when the resistor power supply line is not connected, and is one digit larger than the standard resistance value defined in the SCSI standard (ANSI X3.131-1986). This is achieved by providing a built-in terminating resistor whose combined resistance with the external resistance connected to the SCSI port at the same time when the bus is connected has the standard resistance value or a resistance value near the standard resistance value.

[0009]

When the data processing device is used alone without the SCSI bus being connected, the current flowing through the terminating resistor can be small, and power can be saved. When connecting a SCSI bus, the combined resistance of the external resistance connected to the outside and the built-in terminating resistance becomes the terminating resistance of the bus, and this value becomes the standard resistance value. Disappear.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a main part of a data processing device according to an embodiment of the present invention. SCS of data processing device body 8
The I control circuit 9 is provided with built-in termination resistors 13 and 14 that are one digit larger than the termination resistance values (220 ohms and 330 ohms) defined by the SCSI standard. This resistor 13,
In the present embodiment, the resistance values of 14 are 2.2 kΩ,
It is 3.3k ohms. The built-in terminating resistors 13 and 14 and the internal power supply (+ 5V) form a transistor 30.
When the signal level of the signal line 12 connected to the base of the transistor 30 is LOW, the transistor 30 is turned on to connect the internal power supply and the built-in termination resistors 13 and 14, and the signal level of the signal line 12 is connected. Is high, the transistor 30 is cut off. Resistance 13
A connection terminal for the term power line is provided at the connection point between the transistor 30 and the transistor 30, and a connection terminal for the general signal line is provided at the connection point between the resistors 13 and 14 and the driver receiver circuit.

In this embodiment, the external resistor 15 can be connected to the same SCSI port as the term power line (the connector 10 for the term power line and the external resistor 1).
Two of the five connection connectors 11 are provided. ). The external resistor 15 comprises resistors of 220 ohms and 330 ohms connected in parallel to the internal terminating resistors 13 and 14, respectively, and when the resistor 15 is connected to the SCSI port, a combined resistance with the internal terminating resistors 13 and 14 is provided. Is the terminating resistance. The combined resistance is 200 ohms and 300 ohms, which is slightly different from the standard value, but this difference does not pose any practical problem. Of course, the built-in terminating resistors 13 and 14 are used to meet the standard accurately.
And the value of the external resistor 15 can be selected.

As for the termination resistance value of the SCSI standard, the SCSI bus length is the maximum standard value (6 m in the case of single ended).
When the SCSI bus length is short and a protection measure against noise etc. is taken, the terminating resistance with a resistance value larger than the standard value is practically used as the SCSI resistance. Normal operation is possible even with only one side of the bus attached. Therefore, it is possible to perform a normal operation even when using a resistor that is an order of magnitude larger than the standard value as in the present embodiment, and it is possible to significantly reduce power consumption. On the other hand, utilizing the portability of this data processing device,
This small data processor may be connected to a system of a high-performance computer and its external devices connected by the SI bus by the SCSI bus. In this case, it is preferable that the terminating resistor is connected to both ends with a resistor having a value conforming to the standard or close to the standard value. Therefore, in this embodiment, the purpose is achieved by connecting the external resistor 15 to the connector of the SCSI port.

An external SC for the data processing device 8 shown in FIG.
When connecting to the SI device, the signal level of the signal line 12 is set to the HIGH level to turn off the transistor 30. As a result, the internal terminating resistors 13 and 14 are disconnected from the internal power source, and at the same time, the internal power source is prevented from supplying power to the terminal ends of other SCSI devices (not shown) via the term power lines. Even when the data processing device 8 is located at the end of the SCSI bus in connection with another SCSI device, the signal level of the signal line 12 is set to HIGH to turn off the transistor 30 to separate the internal power supply from the term power line. Then, by connecting the external resistor 15, according to the standard (in the illustrated embodiment, as described above, the substantially standard 20
0 ohms and 300 ohms. ) Is the terminating resistance.

FIG. 2 is a block diagram of a SCSI system using the data processor of this embodiment. The high performance computer 1 has external SCSI devices 4 and 6 on the SCSI bus 2.
2 are connected. In this SCSI bus 22,
The portable small data processing devices 8 and 17 are connected. Each of the data processing devices 8 and 17 incorporates the SCSI control circuit 9 shown in FIG. 1 or a SCSI control circuit 18 having a similar configuration. If the data processing device 17 has a built-in SCSI device, the built-in termination resistor 1 as shown in FIG.
3 and 14 are unnecessary. When the data processing device 8 is separated from the system and used independently, power is consumed by the built-in resistors 13 and 14 having a large resistance value as described above, so that power saving can be achieved. Further, as shown in FIG. 2, by connecting to the high-performance computer 1, various wide-range data exchanges are possible. Various interfaces 20 other than SCSI are connected to the high-performance computer 1 via the CPU board 19, and each exchanges data of another place through its own bus 21, so that the data processing devices 8 and 17 utilize this. It becomes possible. On the SCSI bus of this system, it is not identified whether the connected device is a data processing device such as a computer or a peripheral device, and the bus is based on the ID number assigned to each SCSI device. The priority order of the usage right is determined, the controlling side (initiator) and the controlling side (target) are determined by arbitration between devices, and their roles can be exchanged. Therefore, if the ID number of the computer can be changed by software and is configured to operate as a target, even if it is a small portable computer, almost all resources of the connected device can be used, and It becomes possible to develop new usage patterns of computers.

[0015]

According to the present invention, the problem of power consumption related to the SCSI terminating resistance is solved, and even a small data processing device such as a battery-powered type can incorporate a SCSI control circuit. Therefore, the SCSI bus is used. This data processing device can be connected to a large-scale system.

[Brief description of drawings]

FIG. 1 is a main part configuration diagram of a data processing device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a state in which the data processing device shown in FIG. 1 is connected to a large-scale system.

FIG. 3 is a connection diagram of a conventional SCSI bus.

4 is a main part configuration diagram of the data processing apparatus shown in FIG. 3. FIG.

[Explanation of symbols]

3, 4, 5, 6, 16 ... SCSI device, 8 ... Data processing device, 9 ... SCSI control circuit, 10, 11 ... External connection connector, 13, 14 ... Built-in termination resistor, 15 ... External resistor, 22 ... SCSI bus.

Claims (1)

[Claims] 1. A SCSI (Small Computer System Inte)
rface) In a data processing device having a built-in bus control circuit, a means for disconnecting a power supply line for a terminating resistor of a SCSI bus, which is connected when a SCSI bus is connected to a SCSI port, from a built-in power source; Is a built-in terminating resistor for the SCSI bus that consumes the power of the internal power supply when not connected to the SCSI standard (ANSI X3.131-
1 digit larger than the standard resistance value specified in 1986).
Data processing comprising a built-in terminating resistor whose combined resistance with an external resistance connected to a SCSI port at the same time when the CSI bus is connected becomes the standard resistance value or a resistance value near the standard resistance value. apparatus.