JPS6345658A - Write protection/cancellation setting mechanism - Google Patents

Abstract

PURPOSE:To eliminate miserasion of important data by providing a switch that inhibits and release the writing actions to a memory. CONSTITUTION:A write inhibition switch is set and released with operation of a write inhibition/release switch 9 set into a card. A point D is set at a Hi level while the switch 9 secures connection between A and B. When a write signal WE=Hi-level is applied to a WE terminal from an equipment, the output of a NAND gate 6 is set at a Lo level at a point F and a memory IC 5 becomes writable. When a write inhibition state is set, the connection is secured between B and C with operation of the switch 9. Under such conditions, the point D is set at a Lo level and the output of the NAND gate is kept at a Hi level despite application of the signal WE=Hi-level. Thus a write state is never obtained and therefore it is possible to prevent miserasion due to an inadvertent operation or a malfunction of the equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electronic circuit incorporating a memo'J-IC. In particular, RAM (Random Access
MemoryλEEPROM (Electric
grasable programmable lead
The present invention relates to an electronic circuit having a built-in memory, such as Qnly Memory, into which data can be written at any time from an input signal line.

The present invention particularly relates to electronic circuits for the purpose of storing and storing data, such as IC cards with built-in memory (hereinafter referred to as IC memory cards), circuit modules with built-in memory (hereinafter referred to as memory modules), and electronic circuits equipped with such types of electronic circuits. It has high utility value in the system.

[Conventional technology]

In recent years, many attempts have been made to use IC memory cards and memory modules as external storage media or expansion memories in devices such as word processors, personal computers, and typewriters.

These IC memory cards and memory modules are
There is no need for a motor to drive the medium or a reading head drive device, which is necessary for devices using cassette tapes or floppy disks, and this greatly contributes to the miniaturization and weight reduction of devices.

However, the structure (folding υ,
Conventional IC memory cards are not equipped with holes (nails, notches in jackets, etc.), and there is a risk of accidentally erasing important data.

Furthermore, even with conventional cassette tapes and 70 discs, a special mechanism is required to detect the presence or absence of broken nails or notches. The current situation is that it must be included in the

[Problem that the invention seeks to solve]

In the present invention, the write-protection state is not detected by such a physical detection means, but can be detected by circuit processing.

As a result, the present invention does not require a mechanical mechanism or optical detection mechanism for write-protection detection that was always attached to conventional storage media such as cassette tapes and floppy disks, so the present invention can be used as an external memory. It becomes possible to simplify the structure of equipment that uses the card. As a result, it is possible to further reduce the size, weight, and power consumption of devices.

[Means for solving problems]

The drawback of the conventional mechanism is that it physically represents the write-protected state,
This is due to the fact that it was detected by a mechanical mechanism or optical element built into the equipment and converted into an electrical signal.

In the present invention, the memory is directly controlled by linking a physically performed write inhibit operation with electrical switching.

〔Example〕

An embodiment of the circuit configuration of the present invention is shown in FIG.

In the figure, elements and signal lines that are not directly necessary for explaining the present invention are omitted.

The inside indicated by the broken line frame (1) is the path b built in the IC memory card of the present invention. Names enclosed in ellipses outside the dashed line frame represent input/output terminals of the IC memory card.

Vdd and GND are power supply terminals from the outside to the IC memory card, and generally +SV and 'IV are applied to them, respectively. The R/W terminal is a detection terminal that electrically outputs a write-protected state, as set forth in claim 2, and this output level indicates whether the card is in a write-enabled state or in a write-protected state. It can be determined by the device that uses the IC memory card. The WE terminal is a write command signal input terminal from the device, and the write operation to the memory is controlled by the input voltage to the WE terminal.

While the commercially available memo IJ-I CO write terminal is low active (valid when the signal level is LO), this circuit uses the card's write terminal as high active (valid when the signal level is HiO). (becomes) as shown in the diagram. This is to prevent the write signal from being detected as LO level and malfunctioning when the IC memory card is inserted or removed from the device or when the device is powered off. If consideration is given to preventing malfunctions, high activeness is not required, but we believe that adopting the method of this circuit is simple and effective.

The write protect switch is physically set and released by operating a switch (9) built into the card.

Now, when the switch (9) connects AB as shown in FIG. 1, a becomes 1 (i level).

When the write signal WE-Hi level is applied from the device to the WE terminal, the output of the NAND gate (6) at point F in the figure becomes Lo.
level and the memory (5) becomes writable.

When setting the write-protected state, operate the switch (9) to connect BC. In this state, the point in the figure is Lo
Even if the write signal WE=Hi level is applied, the output of the NAND gate is kept at Hi level and does not enter the write state. Therefore, erroneous erasure due to careless operation or device malfunction &C can be prevented. Writing prohibited/
The release state can be confirmed from the outside depending on the position of the switch (9), and the signal level at the dot in the figure is W/R.
Since it is output to the terminal, it can also be electrically detected on the equipment side. By providing this W/R terminal as an input/output terminal, there is no need to provide a mechanical or optical detection mechanism unlike conventional cassette tapes and floppy disks, and the device can be made smaller and thinner. This greatly contributes to the reduction of energy consumption and power consumption.

Another embodiment of the circuit configuration of the present invention is shown in FIG.

As in the case of FIG. 1, elements and signal lines that are not directly necessary for the explanation are omitted.

The inside indicated by the broken line frame (41) is the circuit built into the IC memory card of the present invention. The names and functions of the signal lines are the same as in FIG. The CE terminal is a signal line for equipment to access the IC memory card, and in this diagram it is H.
i is active.

To set the write inhibit state, operate the switch (49) to connect terminals WPI and WPO.

When power is applied and the card is accessed, WP in the figure
I becomes Hi level. When the switch (49) is closed, WPOFi becomes Hi level, and LO is at point A in the figure.
The level will be output. As a result, regardless of the WE terminal input level, a Hi level is output at point E in the figure, and the memo I
Writing to J-IC is not performed. Further, the signal level at point A is output as LO level to the R/W terminal, and it is possible to electrically detect that the write is prohibited.

When switch (49) is opened, wpo becomes LO level.
9. By setting both terminals CE and WE to l (i level), LO level is output to point E in the figure, and the memory enters the write state. Also, point A in the figure becomes Hi level, and s R The /w terminal has l(
i level is output.

FIG. 1 shows an example of a circuit design in which writing is disabled when the switch is open, and FIG. 5 shows an example of a circuit design in which writing is enabled.

Specific structural examples of the switches (9) and (49) in FIGS. 1 and 5 are shown in FIGS. 2 to 4. In FIG. 2, contacts A, B, and C in FIG.
Conductive patterns (12)j (13), (1) on the back side of 1)
4), the switch (9) is formed by a contact spring (15) and a spring holder (16). It goes without saying that the contact spring (15) should be made of a conductive metal or should have a conductive surface treatment. The spring holder (16) is preferably made of an insulating material in consideration of leakage to the outside or electrostatic noise from the outside. A part of the spring holder (16) is formed in a convex shape, and when it is assembled into the frame (17), it is exposed to the outside through a notch provided in the frame and can be manipulated. To change the switch, slide the exposed spring holder protrusion left and right.

FIG. 3 is a diagram showing an example in which a switch operation is performed using an insertion bin instead of a slide switch or a switch. In FIG. 3, the contacts A, B, and C in FIG. 1 are respectively fixed as spring contacts fixed to the circuit board (21) or fixed to other members constituting the memory card, and the spring contacts are fixed to the circuit board (21). Metal piece (22) pressed against (21)
, (25), and (24). Figure 2 (
The conductor (25) corresponding to 15) is integrally molded with the insulating jack (26) corresponding to FIG.
22)+(23)? (24) Write protection and release are performed so that two of the contacts are selected and connected. The write inhibit state and release state are as shown in FIGS. 3(a) and 3(b).

FIG. 4 shows another example of the structure of a write protect switch, in which (a) is a plan view, (b) is a side view, and (e) is a front view. The structure of FIG. 4 is somewhat similar to FIG. Contact pins (32), (33), and (34) corresponding to A, B, and C in FIG. 1 are fixed to the circuit board (51). Second
(15) The conductor corresponding to (25) in Figure 3 is incorporated into the socket (36), and by inserting it, the two bottles can be selectively connected.

In the figure, the socket (36) is replaced by the contact pin (32) (
33) is inserted in the position where it is to be connected.

In the above explanation, the WPI and WPO terminals in FIG.
This corresponds to B and C in FIG.

・[Effects of the invention] The present invention achieves the following by combining a simple mechanism and an electric circuit.
Write protection to memory cards and memory modules/
It has a release function.

Conventional memory cards do not have this type of write inhibit mechanism and are controlled only by write signals from devices.

Therefore, due to user carelessness or equipment malfunction,
There was always the risk of accidentally erasing valuable data, and unless the card itself had data protection features, you had to rely on magnetic tape or floppy disks to store important data.

According to the present invention, even if a write signal is input from the device side, it is possible to incorporate a data protection function into the card itself, thereby eliminating the risk of accidentally erasing important data.

Further, the present invention can change the state of the write protect/release switch by
The card status can be detected automatically from the input/output terminals, and does not require mechanical switches or optical sensors such as those used in conventional cassette tapes and floppy disks to detect the card status.

This not only eliminates the need for a motor drive mechanism like a cassette tape or floppy disk for memory card input/output, but also greatly contributes to making devices smaller, thinner, and lighter.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the circuit configuration of the present invention. FIG. 2 to FIG. 4 are diagrams showing specific structural examples of the write inhibit/release switch section of the present invention. FIG. 5 is a circuit diagram showing another embodiment of the circuit configuration of the present invention. 1.41 ...Frame 2 indicating the built-in range of the memory card
．． 5, 42.45... Backflow prevention diode 4.44
...It is not necessary if the memo IJ-IC used for the built-in battery card for memory backup is a non-volatile memory. 5.45...Memory IC 6...NAND gate 7.8...Pull-down resistor 9...Write protect/release switch 11.21, 31...Circuit board 12-14.22-24. 52-54...Conductor pattern, contact spring or contact pin provided on the circuit board for setting write protection/cancellation 15.25...Switch conductor 1 for short-circuiting the above contacts
6, 26, 56...External insertion part 17 of the switch
．． 27...More than the card frame

Claims (2)

[Claims] (1) A write prohibition/cancellation setting mechanism, characterized in that an electronic circuit incorporating a memory IC capable of both write and read operations is provided with a switch for inhibiting and canceling write to the memory. (2) The write prohibition/cancellation setting mechanism according to claim 1, wherein the write prohibition state or the release state can be detected from the outside as an output signal of an electronic circuit via a signal line.