JPS5815824B2 - Jiki Card No Yomika Souchi - Google Patents

Description

[Detailed description of the invention] The present invention relates to a magnetic card reading/writing device.

Conventionally, magnetic cards MG have been employed as the cheapest external storage devices in programmable electronic desktop calculators (hereinafter referred to as calculators).

Since this card MG does not have a large storage capacity, if one set of data (for example, a function calculation program) cannot fit on one card, it may be stored over several cards.

Therefore, when reading data from this card into the main body of the calculator, the cards must be read in a predetermined order, and if there are a large number of cards, the order of the cards may be mistaken.

Conventionally, a method has been proposed in which when a series of information is divided and recorded on a plurality of magnetic cards, a code (page) representing the order is simultaneously recorded on each magnetic card according to the order of the information.

However, this method requires a separate hardware configuration for recording codes (pages) representing the order on the magnetic card, which requires a significant improvement in the read/write device, and also increases the complexity of the device. This has the major drawback of increasing costs.

The present invention has been made in view of the above-mentioned conventional drawbacks, and focuses on the fact that magnetic cards generally have a SUM check code recorded thereon to detect reading errors. To provide a magnetic card read/write device which can also specify the order and read cards in a predetermined order without making much improvement in the hardware configuration.

The present invention will be explained below with reference to the drawings.

Figure 1 shows the format of the magnetic card MG.
Ai stores a leading SUM check code for control, B1 stores a rear SUM check code, and Data stores predetermined data.

The SUM check code is a code that represents the total number of data in binary.

Here, the relationship between the codes stored in Ai and Bi is as follows.

In the i-th card, Ai=Bi] (However, A1-0)...
・・・・・・■Bi=Ai+ΣNumber of data...
・・・・・・・・・・・・＠Now, the error in the order of the cards MG that are read one after another can be found out as follows.

That is, when a card MG is received, the relationship between the i-th card and the i-i-th card can be known by detecting whether or not formula 0 is established.

Furthermore, it is possible to know whether the card has been read accurately or not, depending on whether or not the 0 formula holds when the i-th card is read.

For example, it can detect if there is dust on the card or if the card is scratched.

Based on the above-mentioned idea, an embodiment will be described in detail with reference mainly to FIG.

Referring to FIG. 2, WR is a read/write device that includes a read/write magnetic head H, magnetic card insertion detection means, and magnetic card termination means (not shown).

DA is a DA converter that converts the digital signal from the memo IJ-M into a signal convenient for writing, or converts the signal from the head H to a digital signal and converts the digital signal from the memo IJ-M to a signal convenient for writing.
It is something that can be supplied to people.

The memo IJM stores the contents written to the magnetic card or the contents read from the magnetic card, and its operation is controlled by a signal from the control section CC1 selection circuit J, which will be described later.

The control unit CC receives an instruction from the keyboard, for example, and
It controls the computer's reading and writing states, as well as the operations and order of other parts, which will become clearer as the operation is explained in detail.

S is a register for storing a check code, and is used to add the contents each time data is input/output.

The arithmetic and comparison circuit FC detects the coincidence between the contents of the bidirectional path line BL and the contents of the S register, or detects the coincidence between the contents of the bidirectional path line BL and the contents of the S register.
Each time there is data passing through L, one of the additions to the contents of the S register is performed, and the selection is made by the selection signal FCP from the control section CC.

The selection circuit J selects which of the contents of the S register and the contents of the memo 'J-M is to be supplied to the pass line BL;
It performs the operation of supplying the write end code signal to the pass line BL, and the operation is also selected by the control unit CC.

G is a gate for detecting the end code.

Next, the operation shown in FIG. 2 will be explained starting from the case of writing to the magnetic card MG.

First, when the card MG is inserted into the device WR, a card insertion signal MGI is supplied to the control section CC.

The control unit CC generates a clear signal C to clear the S register.

The control unit CC then supplies the selection signal MS P=1 to the selection circuit J, so that the circuit J changes the contents of the S register to “0”.
is supplied to the pass line BL.

This content is written by the large converter DA and the head H to the location A1 of the magnetic card MG.

This is the first SUM check code.

Note that since the read/write selection signal SP (in this case "1') is supplied from the control section CC to DA and WR, the device performs the operations necessary for writing.

Next, a selection signal MSP=0 is supplied from the control section CC, and the contents of the memo 'JM are sequentially supplied to the pass line from a predetermined position and are sequentially stored in the MG.

When the contents of the memory M are supplied to the pass line, the selection signal FCP=1 from the control section CC is supplied to the FC, so that the contents of the S register are added each time data is derived.

There are various methods for adding to the S register, such as adding 1 to the S register each time data is derived, or adding each signal on the pass line BL to each bit of the S register. is much more effective as a SUM check.

Note that the S register has a bit capacity two to three times that of data.

In this way, a number corresponding to the number of data written to the card MG is stored in the S register.

Even when one card MG is near the end, if there is a lot of data to be written, the data must be rewritten to the next card. In this case, the following control is performed.

In other words, when the card is near the end, the end detection signal MGD is W.
Control CC is supplied from R.

The control unit CC supplies the end code generation instruction signal END to the circuit J, stops deriving the contents of the memo IJ-M, and
In the circuit J, the end code 11...
Generate 1″.

This end code is added to the S register at the same time as it is written to the card.

Further, this end code is detected by the gate G and supplied to the control section CC as the end code detection signal LT.

This signal LT causes the signal WP to become "1'', and the contents of the S register are supplied to the pass line BL.

This content is the rear SUM check code stored in B1.

Writing to B1 stops the write operation and waits for the next card to be inserted.

When the next card is inserted, signal MGI is generated, but this time the S register is not cleared and the contents of the S register are written to A2.

The following write operations are similar.

Next, the reading operation from the magnetic card will be explained.

In the case of reading, the signal SP becomes "0" and DA and WR perform the reading operation.

First, when the first card MG is inserted, a signal MGI is generated and the S register is cleared as in the case of writing.

Then, when the contents of A1 of the card are read by the reading head and supplied to the pass line BL, the circuit FC performs a comparison match operation, so that the contents of the S register and the contents of A1 are compared.

If these two do not match, it is assumed that there is a mistake in the card, and an error signal Er is generated from the FC, and the operation is stopped.

If the two match, the operation continues and the first data is introduced into the pass line BL.

In this state, predetermined signals FCP and MSP are supplied to circuits FC and J, respectively, so circuit FC adds the contents of pass line BL to the contents of S register, and circuit J stores the contents of pass line in memory. supply

The memo 'J-M operates to store the supplied contents in a predetermined position in response to a signal from the control section CC.

The operation thereafter is exactly the same until the road code is read.

When the end code is detected by the gate G, the input storage operation to the memory M is stopped, and at the same time as the addition of the end code to the S register is completed, the circuit FC selects the comparison match operation.

Therefore, the rear SUM read from B1 of card MG
The check code is compared with the contents of the S register in the FC.

If the two do not match, it is assumed that there is some kind of error in the reading operation or the card, and the PC sends an error signal Er.
occurs.

If there is a match, it continues to operate as if the data has been read normally and waits for the next card to be inserted.

Even if the end code is not detected for some reason, when the card approaches the end, signal MGO is generated and the contents of B1 are compared with the S register.

In this case, an end code is generated from circuit J in advance and memo IJ-
You can also write it in M.

When the next card MG is inserted into WR, the signal MGI is generated, but in this case, the contents of the S register are not cleared.
The content is compared with the newly read leading SUM check code.

If they match, it can be seen that there is no error in the order of the cards, and if they do not match, it can be seen that there is an error in the order of the cards.

As described above, the magnetic card reading/writing device of this description can detect the order in which cards are inserted, and can notify the operator of an error in the order.

The 80M check code also serves as a data check, so it is in the form of the first SUM check code + binary addition, but the 1st, 2nd, 3rd card...
A dedicated code is provided for each of..., and in combination with this, 80
It can also be an M check code.

As described above, the device of the present invention is able to specify the order of magnetic cards by using the 80M check code for detecting errors in reading magnetic cards. The present invention can be configured to read cards, and an inexpensive and practical magnetic card reading/writing device can be provided.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a magnetic card used in the present invention into a fock 1, and FIG. 2 is a block diagram of the device of the present invention. code, MG: magnetic card, Al: leading SUM check code storage section, Bi: rear SUM check code storage section,
WR: read/write device, M: memory, CC: control unit, F
C: Arithmetic and comparison circuit, S: Register.

Claims (1)

[Claims] 1. In a magnetic card read/write device that can record a leading SUM check code and a rear SUM check code for checking reading errors on a magnetic card, when recording a series of information on multiple magnetic cards separately, the previous card Rear S
A means for recording a UM check code as a first SUM check code of a subsequent card; and a means for temporarily storing a rear SUM check code of a previous card when reading the recorded contents of the plurality of magnetic cards; A magnetic card reading/writing device comprising: means for detecting coincidence/mismatch with a leading SUM check code of a card.