JPH06332836A - External peripheral equipment control system utilizing printer port - Google Patents

Abstract

PURPOSE:To control an external peripheral equipment by utilizing a printer port, to utilize a conventional control software as it is and to use a printer by providing two external connection ports for daisy chain connection, connecting one of them to a personal computer system and connecting the other to the printer. CONSTITUTION:The printer port 12 of the personal computer system 11 and the input port 14 of the external peripheral equipment 13 for the daisy chain connection are connected by a cable A15 and the input port 17 of the printer 16 and the output port 18 of the external peripheral equipment 13 for the daisy chain connection are connected by the cable B19. Then, when an SLCTIN signal for selecting the printer 15 active, the control software is utilized as it is as the conventional printer port and the printer is operated. When the SLCTIN signal is not active, the external peripheral equipment other than the printer connected to the printer port is operated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for external peripheral devices in a personal computer, and more particularly,
The present invention relates to an external peripheral device control system using a printer port.

[0002]

2. Description of the Related Art Conventionally, a printer port in a personal computer has been used for the purpose of connecting to a printer. The situation is shown in FIG. In this system, the printer port 21 of the personal computer 20 and the input port 23 of the printer 22 are connected by a printer cable 24, and the print data from the personal computer 20 is printed on the printer 22.

Further, as an example of a conventional system using a printer port, for example, Japanese Patent Laid-Open No. 4-273332 is known.
There is a word processor described in No. 1.

This word processor is characterized in that two printers are used by utilizing a printer selection signal.

[0005]

The above-mentioned prior art aims at connecting a printer, and no consideration has been given to the connection of external peripheral devices other than the printer.

Further, the word processor described in Japanese Patent Laid-Open No. 4-273321 can use two printers in a time-division manner, but is a control software BIOS for controlling the existing printer.
(Basic Input Output System
No consideration was given to using m) as it is.

An object of the present invention is to connect to an external peripheral device by using a printer port and control the external peripheral device, and to use the existing BIOS which is control software for controlling the printer as it is. Then
It is to provide an environment in which the printer can be used.

[0008]

In order to achieve the above object, an external peripheral device control system utilizing a printer port of the present invention includes a personal computer system having a printer port and a printer connected to the printer port. It is composed of external peripheral devices.

[0009]

The external peripheral device control system using the printer port of the present invention is an SLC for selecting a printer.
When the T IN (SELECT INPUT) signal is active, the conventional printer port is used as it is, which is the control software for controlling the printer, that is, BIOS, and the printer is operated to select the printer. When the SLCT IN signal is inactive, the external peripheral device other than the printer connected to the printer port is operated.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram illustrating the concept of an external peripheral device control system using a printer port according to the present invention.

The configuration of the external peripheral device control system using the printer port according to the present invention is such that the printer port 12 of the personal computer system 11 and the input port 14 of the external peripheral device 13 prepared for daisy chain connection are connected by a cable. The connection is made with A15, and the input port 17 of the printer 16 and the output port 18 of the external peripheral device 13 prepared for daisy chain connection are connected with a cable B19.

Specific embodiments will be described below with reference to the drawings.

In the following embodiment, the external peripheral device 1
As an example, a CD-ROM (Compact Disc)
A Read Only Memory) drive is assumed.

FIG. 3 is a block diagram showing a first embodiment of an external peripheral device control system using a printer port according to the present invention. However, the same parts as those in FIG. 1 have the same numbers. The printer port 12 of the personal computer system 11 and the input port 31 of the CD-ROM drive 30 prepared for daisy chain connection are
CD-R prepared for daisy chain connection with input port 17 of printer 16 by connecting with cable A32.
Connect the output port 33 of the OM drive 30 to the cable B3
4 and the printer cable 35.
The connection between the cable B34 and the printer cable 35 is
It is connected to the printer port 12 of the personal computer system 11 by connectors 36 and 37 having exactly the same pin arrangement and signal arrangement.

In FIG. 3, a personal computer system 11 is a Hitachi system device 3010NS.
50 (Personal computer PS / 5 made by IBM, USA
5note equivalent product) is used.

Table 1 shows a system device 301 manufactured by Hitachi Ltd.
The terminal number and signal name of the printer port 12 in 0NS50 are shown.

[0018]

[Table 1]

When outputting print data to a printer,
The personal computer system 11 is -SCLT.
After activating the IN signal, the following steps 1 to 3 are repeated and executed. Print data is output to Data Bit. -Output an active pulse to the STROBE signal. Wait for an active pulse on the ACK signal.

Further, the personal computer system 1
1 is an output signal -INIT signal, if necessary,
-AUTO FEED signal and BUSY which is an input signal
Signals, PE signals, SCLT signals, -ERROR signals, etc. are used.

In FIG. 3, as the CD-ROM drive 30, a Hitachi CD-ROM drive CDR-170 is used.
0S is used.

Table 2 shows the terminal numbers and signal names of the input port 31 and the output port 33 in the Hitachi CD-ROM drive CDR-1700S.

[0023]

[Table 2]

The CD-ROM drive 30 is a CD-RO when the drive selection signal (-DS0 signal) is active.
It operates as an M drive and has a drive selection signal (-DS0
Signal) is inactive, the input / output signal and the output signal are not connected.

CD prepared for daisy chain connection
-Input port 31 and output port 3 of ROM drive 30
3 is coupled inside the CD-ROM drive 30, and the input port 31 and the output port 33 have the same terminal number and the same signal name.

Hitachi-made CD-ROM drive CDR
When reading data recorded on a CD-ROM disc (not shown) from the -1700S, basically, a shake hand of a data transfer request signal (-DREQ signal) and a data transfer response signal (DACK signal) is used. To do.

Table 3 shows the printer port 12 of the personal computer system 11 in the cable A32.
Shows the terminal number and signal name of the input port 31 of the CD-ROM drive 30.

[0028]

[Table 3]

An interface circuit a is inserted in the cable A32.

If it is not necessary for the printer 16 and the CD-ROM drive 30 to operate at the same time, the interface circuit a can be omitted and the CD-ROM directly.
It can also be combined with the drive 30. In this case, every time the printer 16 is used, the printer cable 35
It will be necessary to replace the cable with.

Table 4 shows CD- in the cable B34.
The output port 33 side of the ROM drive 30 and the connector 3
The printer 16 through the printer cable 7 and the printer cable 35.
The terminal numbers and signal names on the side of the connector 36 that is connected to the input port 17 are shown.

[0032]

[Table 4]

An interface circuit b is inserted in the cable B34.

FIG. 4 shows a circuit diagram of the interface circuit a inserted in the cable A32 and the interface circuit b inserted in the cable B34.

The interface circuit a shown in FIG.
Via the inversion circuit 40, the
Send the SCLT IN signal to -D on the CD-ROM drive side.
Converted to S0 signal. That is, when the printer 16 is selected (the -SCLT IN signal is active), the CD-ROM drive 30 is in the non-selected state (-
The DS0 signal is inactive) and the printer 1
The state where 6 is not selected (the -SCLT IN signal is inactive) means that the CD-ROM drive 30 is in the selected state (-DS0 signal is active).

The interface circuit b shown in FIG. 4B is
It is composed of an inverting circuit 41 and a buffer 42. When the printer 16 is selected (-SCLT IN signal is active), the buffer 42 is active, and the personal computer and the printer 16 can exchange signals via the daisy chain circuit of the CD-ROM drive 30. Become. When the CD-ROM drive 30 is in the selected state (the -DS0 signal is in the active state), the buffer 42 is inactive, and the personal computer 11 and the printer 16 are in the unconnected state.

The data bus (Data Bit 7 to 0) in the CD-ROM drive 30 is connected only when the CD-ROM drive 30 is in the selected state (-DS0 signal is active), and the CD-ROM drive 30 is connected.
Is in a non-connected state in the non-selected state (-DS0 signal is inactive state), and the data bus (Data Bit 7 to 0) in the printer 16 is when the printer 16 is in the selected state (-SCLT IN signal is in active state). However, since the -STROBE signal is not transmitted, the bidirectional buffer is not particularly provided by making a comprehensive judgment. Of course, a bidirectional buffer may be provided.

BU, which is an output signal on the printer side,
Regarding the SY signal and the SCLT signal, since the input port 31 and the output port 33 of the CD-ROM drive 30 are connected, the 18th terminal (-
DS3) and 15th terminal (-DS2), 11th terminal (BUSY) and 13th terminal on the personal computer side
It is connected to the number terminal (SCLT). Therefore, the connection,
The buffer for disconnection is omitted.

FIG. 5 shows a flow chart of the personal computer system 11 data transfer software in the embodiment of FIG. 3, and FIG. 6 shows a timing chart of the -DREQ signal and the DACK signal in the CD-ROM drive 30. The operation of the embodiment shown in FIG. 3 will be described below with reference to FIGS.

(Step 50) Initial values are set. In this step, the -SCLT IN signal is deactivated (that is, the -DS0 signal is activated), the DACK signal is deactivated,
Also, the data transfer address and the number of transfer bytes are set.

(Step 51) CD-ROM drive 3
It waits for the -DREQ signal (that is, the PE signal), which is the data transfer request signal from 0, to become the active state (-DREQ signal is 0 level).

(Step 52) -When the DREQ signal becomes active (at times t1 and t5 in FIG. 6),
From the CD-ROM drive 30 to the data bus (DB7-
Data is loaded into the personal computer system 11 via 0). Store the fetched data at the specified transfer address. Add 1 to the transfer address.

(Step 53) CD-ROM drive 3
DACK signal (-AU which is a data transfer response signal to 0
The TO FEED signal) is activated (DACK signal is at 1 level).

(Step 54) When the DACK signal becomes active (at t2 and t6 in FIG. 6), CD
The -ROM drive 30 puts the -DREQ signal in the inactive state (at t3 and t7 in FIG. 6). Therefore, the DACK signal is made inactive (DACK signal is at 0 level).

(Step 55) When the DACK signal becomes inactive (at t4 and t8 in FIG. 6), C
If there is data to be transferred, the D-ROM drive 30 makes the -DREQ signal active again (at time t5 in FIG. 6). If there is no data to transfer, −
Continue the inactive state of the DREQ signal. If the specified number of transfer bytes has not ended, step 51
Returning to step 56, when the designated number of transfer bytes is completed, the process proceeds to the next step 56.

(Step 56) The data transfer process is terminated.

In this embodiment, the inactive state of the -DREQ signal is not detected by software, but the CD-ROM
Since the drive 30 detects the active state of the DACK signal and makes the -DREQ signal inactive (t2 to t3, t6 to t7 in FIG. 6), it is sufficiently short as compared with the processing of the data transfer software. , Practically no problem. Also, for the same reason, although the process returns from step 55 to step 51, step 50 of detecting the active state of the -DREQ signal by software may be omitted and the process may return to step 52.

FIG. 7 is a circuit diagram showing a second embodiment of an external peripheral device control system using a printer port according to the present invention. The interface circuit c of FIG. 7 shows another embodiment of the interface circuit a inserted in the cable A32 of FIG.

Further, FIG. 8 shows a flow chart of the personal computer system 11 data transfer software in the embodiment of FIG. 7, and FIG. 9 shows a timing chart of main signals in the circuit c of FIG. The specific operation of the embodiment shown in FIG. 7 will be described below with reference to FIGS. 8 and 9.

(Step 80) Initial values are set. In this step, the -SCLT IN signal is deactivated (that is, the -DS0 signal is activated), the DACK signal is deactivated,
Also, the data transfer address and the number of transfer bytes are set. The DACK signal is made inactive by setting the -AUTO FEED signal (signal a700) to 0 level. When the signal a700 is at the 0 level, the two D latch circuits 71 and 72 perform signal delay (signal c702 and signal d703) using the output signal (signal b701) of the oscillator 70 as a clock signal, and the output signal (signal d703). ) And the signal a700 as input signals, the output signal of the EXOR circuit 73 (signal e7
04) becomes 0 level. As a result, the NAND circuit 7
The selection circuit consisting of 4,75,76 is -SCLT IN
The signal is inactive (by the inverting circuit 77, -DS
Since the signal e is transmitted when the 0 signal is in the active state, the DACK signal (signal g706), which is a response signal of the -DREQ signal (signal f705), is in the inactive state (0 level).

(Step 81) CD-ROM drive 3
It waits for the -DREQ signal (that is, the PE signal), which is the data transfer request signal from 0, to become the active state (-DREQ signal is 0 level).

(Step 82) -When the DREQ signal becomes active (at time t1 in FIG. 9), CD-
Data is fetched from the ROM drive 30 to the personal computer system 11 via the data bus (DB7-0). Store the fetched data at the specified transfer address. Add 1 to the transfer address.

(Step 83) -The AUTO FEED signal (signal a700) is set to 1 level. Then, the output signal of the D-latch circuit 71 (signal c702) becomes 1 level at the rising edge of the signal b (time t2 in FIG. 9), and at the rising edge of the next signal b, the D-latch circuit 7
The output signal of 2 (signal d703) becomes 1 level (FIG. 9).
(At time t4). As a result, the output signal of the EXOR circuit 73 (signal e704) becomes a 1-level pulse (time t2 to t5 in FIG. 9), and the DACK signal (signal g706) becomes an active-state (1-level) pulse. When the DACK signal (signal g706) becomes active (time t2 in FIG. 9), the CD-ROM drive 30 sets the -DREQ signal (signal f705) inactive (time t3 in FIG. 9). Also, D
When the ACK signal (signal g706) becomes inactive (at time t5 in FIG. 9), the CD-ROM drive 3
0 sets the -DREQ signal (signal f705) to the active state (time t6 in FIG. 9).

(Step 84) The same process of Step 82 is performed.

(Step 85) Contrary to Step 83,
The AUTO FEED signal (signal a700) is set to 0 level (time t7 in FIG. 9). Then, the output signal of the D latch circuit 71 (signal c702) becomes 0 level at the rising time of the signal b (time t9 in FIG. 9), and at the rising time of the next signal b, the output signal of the D latch circuit 72 (signal d703) becomes 0 level (at time t10 in FIG. 9). As a result, the output signal (the signal e704) of the EXOR circuit 73 becomes a 1-level pulse (at time t7 to t10 in FIG. 9), and the DACK signal (the signal g70).
6) is a pulse in the active state (1 level).
The DACK signal becomes active (t in FIG. 9).
7) and the CD-ROM drive 30 is -DREQ.
The signal (signal f705) is set to the inactive state (time t8 in FIG. 9).

(Step 86) When the DACK signal becomes inactive (at time t10 in FIG. 9), CD-
If there is data to be transferred, the ROM drive 30-
The DREQ signal (signal f705) is set to the active state again (time t1 in FIG. 9). If there is no data to transfer, continue the inactive state of the -DREQ signal. If the specified number of transfer bytes has not ended,
Returning to step 82, when the designated number of transfer bytes has ended, the routine proceeds to the next step 87.

(Step 87) The data transfer process is terminated.

In this embodiment, since 2-byte data is transferred in one loop, the number of loops is half that in the embodiment of FIG. This is not a practical problem because the number of data transfer bytes is an even number.

Since the number of processing steps per byte is reduced by one step as compared with the embodiment of FIG. 4,
The processing speed can be increased.

When using a printer, -SCLT
By setting the IN signal to the active state (0 level), the selection circuit including the NAND circuits 74, 75, and 76 outputs the -AUTO FEED signal as it is as the signal g.

FIG. 10 is a circuit diagram showing a third embodiment of an external peripheral device control system using a printer port according to the present invention. Interface circuit d in FIG.
Shows another embodiment of the interface circuit a inserted in the cable A32 in FIG.

FIG. 11 is a flow chart of the personal computer system 11 data transfer software in the embodiment of FIG. 10, and FIG. 12 is a circuit d of FIG.
The timing charts of the main signals in FIG. The specific operation of the embodiment shown in FIG. 10 will be described below with reference to FIGS. 11 and 12. However, in FIG.
The same items as are numbered the same.

(Step 110) Initial values are set.
In this step, the -SCLT IN signal is set to the inactive state (that is, the -DS0 signal is set to the active state), the DACK signal is set to the inactive state, and the data transfer address and the number of transfer bytes are set. . The DACK signal is made inactive by setting the -AUTO FEED signal (signal a1000) to 0 level. If the signal a1000 is at 0 level, the -DREQ signal (signal b1001)
The output signal (signal c1002) of the inverting circuit 100 and the output signal (signal d1003) of the AND circuit 101 that receives the signal a1000 become 0 level. As a result, the two D latch circuits 71 and 72 perform signal delay (signal f1005 and signal g1006) using the output signal (signal c1004) of the oscillator 70 as a clock signal, and the signal f
The output signal (signal h1007) of the AND circuit 102 having the input signals 1005 and the signal g1006 becomes 0 level. As for the output signal (signal h1007), the DACK signal (signal i1008) which is a response signal of the -DREQ signal (signal b1001) becomes inactive (0 level), as in the embodiment of FIG.

(Step 111) The -DREQ signal (that is, the PE signal) which is the data transfer request signal from the CD-ROM drive 30 is in the active state (-DRE).
Wait until the Q signal becomes 0 level).

(Step 112) When the -DREQ signal (signal b1001) becomes active (at time t1 in FIG. 12), -AUTO FEED signal (signal a1).
000) to 1 level (time t2 in FIG. 12).

(Step 113) Data is loaded from the CD-ROM drive 30 to the personal computer system 11 via the data bus (DB7-0). Store the fetched data at the specified transfer address. Add 1 to the transfer address. If the signal a1000 is 1 level, the output signal (signal c1002) of the inverting circuit 100 of the -DREQ signal (signal b1001) and the signal a1
The output signal (signal d1003) of the AND circuit 101 having 000 as its input becomes 1 level. Then, the output signal of the D latch circuit 71 (signal f1005) becomes 1 level at the rising edge of the signal e1004 (t in FIG.
At time t3, t8), the output signal (signal g1006) of the D latch circuit 72 becomes 1 level at the next rising of the signal e1004 (time t4, t9 in FIG. 12). As a result, the output signal of the AND circuit 102 (the signal h100
7) becomes a 1-level pulse (t4 in FIG. 12).
~ T6, t9 to t11), DACK signal (signal i1)
008) is a pulse in the active state (1 level). When the DACK signal (signal i1008) becomes active (at t4 and t9 in FIG. 12), the CD-R
The OM drive 30 uses the -DREQ signal (signal b100
1) in the inactive state (t5, t10 in FIG. 12)
Time point). Also, the DACK signal (signal i1008)
Becomes inactive (t6 and t1 in FIG. 12)
1 time), and the CD-ROM drive 30 is -DREQ
The signal (signal b1001) is brought into the active state (at time t7 in FIG. 12).

(Step 114) DACK signal (signal i
1008) becomes inactive (at t6 and t11 in FIG. 12), the CD-ROM drive 30
If there is data to be transferred, the -DREQ signal (signal b1
001) is made active again (at time t7 in FIG. 12). -DREQ if there is no data to transfer
The inactive state of the signal (signal b1001) is continued. That is, the signal a1000 is in the inactive state (1
Level), the -DREQ signal (signal b1001)
The output signal (signal c1002) of the inverting circuit 100 and the output signal (signal d1003) of the AND circuit 101 that receives the signal a1000 become 0 level. Then, the output signal (signal f1005) of the D latch circuit 71 is changed to the signal e10.
At the rising edge of 04, the level becomes 0 (at t6 and t11 in FIG. 12), and at the rising edge of the next signal e1004, the output signal of the D latch circuit 72 (signal g10).
06) becomes 0 level (t8, t12 in FIG. 12)
Time point). As a result, the output signal (signal h1007) of the AND circuit 102 becomes 0 level (t in FIG. 12).
6, time t11), DACK signal (signal i1008)
Becomes an inactive state (level 0). If the specified number of transfer bytes is not completed, step 113
Returning to, when the designated number of transfer bytes is completed, the process proceeds to the next step 115. (Step 115) Contrary to step 83, the -AUTO FEED signal (signal a10
00) to 0 level (time t13 in FIG. 12). As a result, for the same reason as step 110, the DAC
The K signal (signal i1008) becomes inactive (at time t13 in FIG. 12).

(Step 116) The data transfer process is terminated.

In this embodiment, the number of processing steps per byte is reduced by one step as compared with the embodiment of FIG. 7, so that the processing speed can be further increased.

Although the interface circuit is stored in the connection cable in the above embodiments, it may be stored in the connector.

The power supply to the interface circuit may be independently prepared, but the interface circuit used in the above embodiments is a CMOS IC (Comp.
elemental metal-oxide-sem
iconductor integrated cir
Since it is configured by a CIT), a signal (for example, DS8) that requires a small current and has a normal signal level of the power supply voltage (+ 5V) may be used.

In FIG. 7 and FIG. 10, the oscillator is used independently and the output signal is used. However, the clock signal generated in the CD-ROM drive is used as it is, or if necessary, the frequency is divided. May be processed and used.

FIG. 13 is a block diagram showing a fourth embodiment of an external peripheral device control system using a printer port according to the present invention. However, the same components as those in FIG. 3 have the same numbers.

A switching circuit 130 is provided between the printer port 12 of the personal computer system 11 and the input port 31 of the CD-ROM drive 30 prepared for daisy chain connection.
30 has an input / output port 131 for the personal computer system 11 and an input / output port 132 for the CD-ROM drive 30, as well as an input / output port 133 for the printer 16.

The personal computer system 11 and the switching circuit 130 are connected by a cable C134, and the switching circuit 130 and the input port 31 of the CD-ROM drive 30 prepared for daisy chain connection are connected by a cable D135. In addition, the switching circuit 130
Since the input / output port 133 for the printer 16 has the same pin arrangement and signal arrangement as the printer port 12 of the personal computer system 11, the switching circuit 130 and the printer 16 are connected by the conventional printer cable 35.

The input / output port 131 for the personal computer system 11 in the switching circuit 130 needs to transmit a necessary signal. Therefore, in this embodiment, the printer port 1 of the personal computer system 11 is used.
The pin arrangement and the signal arrangement are exactly the same as those in No. 2.

Similarly, the CD in the switching circuit 130
The input / output port 132 for the -ROM drive 30 has exactly the same pin arrangement and signal arrangement as the input port 31 of the CD-ROM drive 30 prepared for daisy chain connection.

FIG. 14 is a circuit diagram showing a specific circuit e of the switching circuit 130.

The circuit e of FIG. 14 is composed of an inverting circuit 140, a buffer 141 and a buffer 142.

The state where the printer 16 is selected (-S
When the CLT IN signal is active), buffer 1
41 becomes active, and signals can be exchanged between the personal computer system 11 and the printer 16.
At this time, the CD-ROM drive 30 is in the non-selected state (-D
Since the S0 signal is inactive), the buffer 1
42 becomes inactive, and the personal computer system 11 and the CD-ROM drive 30 are disconnected.

The CD-ROM drive 30 is in the selected state (-
When the DS0 signal is in the active state), the buffer 141 is inactive, and the personal computer system 11 and the printer 16 are in the non-connection state. At this time,
Since the CD-ROM drive 30 is in the selected state (-DS0 signal is in the active state), the buffer 142 becomes active and the personal computer system 11 and the C
Signals can be exchanged with the D-ROM drive 30.

On the CD-ROM drive side, a circuit equivalent to that shown in FIG. 7 or 10 may be added to speed up the processing.

In the present embodiment, the switching circuit is provided between the personal computer system and the CD-ROM drive.
It may be stored in the connector.

The power supply to the switching circuit may be independently prepared, but the switching circuit is a CMOS.
IC (Complementary metal-ox)
ide-semiconductor integra
Since it is configured with a ted circuit, the current required is small and the normal signal level is the power supply voltage (+5).
V) signals (eg DS8) may be used.

In the above-described embodiment, by setting the printer selection signal to the active state, it is possible to perform exactly the same operation as the conventional printer, and the BIOS which is the control software for controlling the existing printer. (BasicInput Output
System) can be used as it is.

In the above embodiments, the printer port of the personal computer system is assumed to be a printer port that generates a necessary signal by software processing. However, the printer port IC (i
Even with a personal computer system using an integrated circuit, the present invention can be realized with the same idea as the present invention.

In the above embodiment, the external peripheral device 1
As an example, a CD-ROM drive is assumed, but it goes without saying that any external peripheral device is not limited to the CD-ROM drive as long as the printer port is available.

[0088]

The external peripheral device control system using the printer port of the present invention can connect to the external peripheral device using the printer port and control the external peripheral device.

Further, it is possible to use the printer by directly using the BIOS, which is the control software for controlling the existing printer, as it is.

There are effects such as the following.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a concept of an external peripheral device control system using a printer port according to the present invention.

FIG. 2 is a block diagram showing a conventional embodiment.

FIG. 3 is a block diagram showing a first embodiment of an external peripheral device control system using a printer port according to the present invention.

FIG. 4 is an interface circuit a inserted in the cable A and an interface circuit b inserted in the cable B.
It is a circuit diagram of.

5 is a flow chart of personal computer system data transfer software in the embodiment of FIG.

FIG. 6 is a timing chart of the −DREQ signal and the DACK signal in the CD-ROM drive.

FIG. 7 is a circuit diagram showing a second embodiment of an external peripheral device control system using a printer port according to the present invention. 4 shows another embodiment of the interface circuit a inserted in the cable A32 in FIG.

FIG. 8 is a flowchart of personal computer system 11 data transfer software in the embodiment of FIG.

9 is a timing chart of main signals in the circuit c of FIG.

FIG. 10 is a circuit diagram showing a third embodiment of an external peripheral device control system using a printer port according to the present invention. 4 shows another embodiment of the interface circuit a inserted in the cable A32 in FIG.

11 is a flowchart of personal computer system data transfer software in the embodiment of FIG.

12 is a timing chart of main signals in the circuit d of FIG.

FIG. 13 is a block diagram showing a fourth embodiment of an external peripheral device control system using a printer port according to the present invention.

FIG. 14 is a circuit diagram showing a specific circuit e of a switching circuit.

[Explanation of symbols]

11, 20 ... Personal computer system 12,
21 ... Printer port, 13 ... External peripheral device, 14 ...
External peripheral input ports, 15, 32 ... Cable A,
16, 22 ... Printer, 17, 23 ... Printer input port, 18 ... External peripheral device output port, 19, 3
4 ... Cable B, 24, 35 ... Printer cable, 3
0 ... CD-ROM drive, 31 ... CD-ROM drive input port, 33 ... CD-ROM drive output port, 36, 37 ... Connector, 40, 41, 77, 10
0, 140 ... Inversion circuit, 42, 141, 142 ... Buffer, 70 ... Oscillator, 71, 72 ... D latch circuit, 73 ...
EXOR circuit, 74, 75, 76 ... NAND circuit, 10
1, 102 ... AND circuit, 130 ... Switching circuit, 13
1 ... Input / output port of switching circuit for personal computer system, 132 ... Input / output port of switching circuit for CD-ROM drive, 133 ... Input / output port of switching circuit for printer, 134 ... Cable C, 135 ... Cable D.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Usami, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa, Ltd. Information & Video Media Division, Hitachi, Ltd. (72) Inventor Yukio Fukui 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Hitachi, Ltd. Visual Media Research Center

Claims (10)

[Claims] 1. A personal computer system having a printer port, wherein an external peripheral device other than a printer is connected to the printer port, and the printer port is used to control the external peripheral device. External peripheral device control system using ports. 2. The external peripheral device has two external connection ports for daisy chain connection, one of which is connected to a personal computer system and the other is connected to a printer. An external peripheral device control system using the printer port according to claim 1. 3. An interface circuit is added to each of a connection cable connecting between the personal computer system and the external peripheral device and a connection cable connecting between the external peripheral device and the printer. An external peripheral device control system using the printer port according to claim 2. 4. An interface circuit is added to each of a connector for coupling between the personal computer system and the external peripheral device and a connector for coupling between the external peripheral device and the printer. An external peripheral device control system using the printer port according to claim 2. 5. The personal computer system,
A switching circuit is added between the external peripheral device and the switching circuit, and the switching circuit is provided not only for two connection ports for the personal computer system and the external peripheral device, but also for the printer. The external peripheral device control system using a printer port according to claim 1, further comprising a connection port. 6. The external peripheral device control system using a printer port according to claim 5, wherein the switching circuit is stored in the external peripheral device. 7. The printer port according to claim 1, wherein the power supplied to the interface circuit and the switching circuit is supplied from a signal whose normal signal level is a power supply voltage level. External peripheral device control system. 8. The personal computer system comprises:
8. The external peripheral device control system using a printer port according to claim 1, wherein a response signal to a data transfer request from the external peripheral device is set to an active state or an inactive state according to an output level by software. . 9. The personal computer system comprises:
8. The external peripheral device using a printer port according to claim 1, wherein the response signal to the data transfer request from the external peripheral device is made into a pulse in an active state by a front edge or a rear edge by software. Control system. 10. A response signal to a data transfer request from the external peripheral device is set to an active state pulse by hardware.
An external peripheral device control system using the described printer port.