JPS5991562A - Method for protecting incorrect access in multimaster system - Google Patents

Abstract

PURPOSE:To prevent the incorrect access of a multi-master system by discriminating a master card in using a bus on a common bus and checking the address of the common bus to prevent the access of an address outside of an area. CONSTITUTION:Since a read signal *RD or a write signal *WT is ''L'' during the access of a slave card, an address signal on the common bus is entered at the ''L'' timing of the *RD or *WT, and said address signal is compared with address data stored in an area address registering memory 8 by address size discriminators 10, 11. The address size discriminators 10, 11 discriminate whether the address signal is the address in the area stored in the memory 8 or not and decide the correctness/incorrectness of the address after tA hours from the time turning the read signal *RD or the write signal *WT to ''L''. In case of an incorrect address, an address error signal *AER is turned to ''L'' and the information indicating that the address is incorrect is sent to the slave card.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a multi-mask system configured to include a plurality of mask cards and a slave card that can be accessed in common by the plurality of mask cards. When a mask card attempts to access a slave area that does not exist (2), the multi-master system detects that the access is an erroneous access, and notifies the master card (2) of erroneous access protection. Method (Related to 1.

Technical Background When a multi-mask system is configured by connecting multiple mask cards and a slave card that can be accessed in common to the multiple mask cards, the mask cards are connected via a common path. It is a card that can acquire rights for itself, and it is also a card that can access slave cards.

A slave card is, for example, a memory card.

Mask card commands (input cards, output cards, etc.)
The second card is thus accessed.

Prior Art and Problems FIG. 1 shows an example of the system configuration and common bus of a conventional multi-mask system. 1 is a path control card, 2-1.2
-2 is a mask card, Ro-1, Ro-2 are memory cards,
4-1 and 4-2 are input/output cards, B is a common bus, A is an address section, D is a data section, C8 is a control signal section, BC is a path usage right control signal section, and CC is a common lock section. .

Note that * is a signal display, A, ~A115 are addresses, and D
o ”-D 1a is data, RD is read, WT is write, ACK is acknowledgment return, BRQo-BRQ2
is the mask card number in use of the common pass, PSGo-P
SG2: Pass usage permitted, BBSY: Pass in use, CLK
is the clock.

Conventional multi-mask system configuration (2), recent L
With the progress of SI technology and the multifunctionality of microprocessor application systems, the number of mask cards that share a common bus has become large, ranging from several to more than ten. Therefore, multiple mask cards commonly access memory cards that store various types of data.
There is a possibility that the area allocated to a specific mask card (-2) may be accessed by other 7-star cards. As a result, the following problem occurs.

(1) Destroying the memory of data on memory cards, output cards, etc.

(2) Data in different areas is not judged as an error (1 yield 1) and is used in a complicated manner.

These spoons occur due to the following reasons (= therefore.

That is, (1) Defective address line: This is due to a defective address bus gate of the mask card, a defective address section, or a defective address line of the slave card.

(2) Defective mask card: This is caused by a defect in the arithmetic unit of the microprocessor, a defect in the logic within the mask card, etc.

In this case, if the address line in (1) is defective (two), it can be checked by adding -parity to the address line (-) to prevent the problem from occurring, and this is currently in practical use (1). Defective mask cards (2) (In A, the following countermeasures have been taken.

(1) Preventing writing to the program storage area of a memory card. In other words, since programs are originally read-only data, this can be prevented by checking whether an attempt has been made to write data to the program storage area (-). .

(i) Self-diagnosis of the address to be accessed when the master card acquires the right to use the common bus (secondary prevention).

However, both methods i) and (i) are not satisfactory methods because the areas in which erroneous access can be prevented are limited, and the reliability of self-diagnosis cannot be guaranteed quantitatively (difficult to express). do not have.

OBJECTS OF THE INVENTION An object of the present invention is to identify a mask card that is using a path on a common path, check the addresses on the common path, and prevent access to addresses outside the area. To provide a protection method against erroneous access in a multi-master system that reliably prevents erroneous access in a multi-mask system (there are two methods).

Embodiment of the Invention FIG. 2 shows the configuration of an embodiment of the path control card 1 of the invention. The same symbols as in FIG. 1 indicate the same parts.

5 is an address input gate, 6-1 to 6-3 are mask number read gates during pass use, 7 is a strobe read gate during bus access, 8 is an area address registration memory, 9-
1 to 9-6 are gates, 10 and 11 are address size discriminators, 12 is a timer, 13-1-13-3 are gates, and I
RTo-I RT2 is an interrupt request signal, and AER is an address error signal.

FIGS. 3 and 4 show operational charts of signals on the common path. FIG. 6 shows the data reading operation of the slave card, and FIG. 4 shows the data writing operation of the slave card. As shown in FIGS. 3 and 4 (2. While the slave card is being accessed, the read signal *RD or write signal *wT is 'Low' (hereinafter referred to as "L"), so the signal *RD or The address signal on the common path is taken in at the timing when Shima*WT is "L#", and the address signal and the address data stored in the area address registration memory 8 are compared by the address size discriminators 10 and 11.Area address The registration memory 8 is an element that stores addresses of areas that may be accessed, for example, RO.
M is used. The address size discriminators 1 and 11 compare whether or not the address is within the area stored in the area address registration memory 8.
The acceptability of the address is determined after tA time from RD or *wT being "L". If not, the address error signal *AE is output as shown in the operation chart for out-of-area access shown in FIG.
Set R to "L" and notify the slave card that the address is defective. tl of the timer 12 is the write signal *WT in FIG. 4 becomes "L" (-, access confirmation return signal *
ACK must be set to ``L'' (2) shorter than the time tA, and the slave card must not receive the write signal ＊wT when the address error signal ＊AER is ``L'' ( From 2, the signal *AER
When is "L", writing of data to the address can be prevented. For mask cards that are using a common pass at the same time,
Interrupt request signal' via gates 13-1 to 13 =-3
Output fCI RTo~* I RT 2. The signal * I RT o - * I RT 2 is set as a window for master cards 0 to 2 (not shown) (two pairs), and the CPU (not shown) in the mask card is enabled for direct interrupts. , Mask card for out-of-area access in real time (
Two notices may be given.

FIG. 6 shows the configuration of another embodiment of the path control card 1 of the present invention. The same symbols as in FIG. 2 indicate the same parts. 14 is a differentiation circuit, 15 is an access confirmation return signal *AC
It is written as K memory flip-flop CPL lower F/F. ), 1
6 is a CPU. Common path signal operation chart (2) The data reading and data writing operations of the slave card are the same as those shown in FIGS. 3 and 4 of the embodiment in FIG. 2, so their explanation will be omitted. FIG. 7 (shows an operation chart at the time of out-of-area access in the embodiment shown in Part 2 and FIG. The CPU 16 inputs the defective address data and mask card number, stores it once, and then sends the signal *ACK.
Set memory F/F 15 and set the signal *ACK to L'
l2. In this case, in the slave card, if the address error signal *AER is "L", the mask card does not release the right to use the path by setting C2 so as not to return the address error signal *AER. It can be left in use. Therefore, since the address signal does not change, the CPU 16 can reliably memorize the defective address and mask card number. In this way, the access confirmation return signal * When the slave card transfers the ACK to "L", the defective mask card releases the right to use the path.The following operations (two steps are not shown in the diagram, but first lock the right to use the path) During this lock, investigation of the history of defective mask cards, etc.
The PU 16 can take various highly functional measures, such as determining whether to remove a defective mask card or switching to another mask card. If the data in the area address registration memory 8 can be changed by the CPU 16, more flexible checking becomes possible. The embodiment shown in Figure 2 (2) uses ROM if the access area is fixed as a system, and uses RAM (2) to freely change the contents via a common bus if the memory needs to be changed. Also, if there is no need to notify the mask card, the gates 13-1 to 16-6 and interrupt request signals *IRT, ~ *IRT2 are unnecessary. Even if notification is necessary, each master card It is not necessary to set the number of signal lines to correspond to each case.

Further, if the system can be stopped, the address error signal *AER is not necessary. Area address registration memory8.
By providing two address size discriminators io and i1 for each read signal *RD and write signal *WT, more detailed checks can be performed.Furthermore, in the embodiment shown in FIG. * By providing a means for sending back ACK on behalf of the slave card (two), it becomes possible for the CPU 16 to confirm and store defective data.

Effects of the Invention As detailed above (2) According to the present invention, the area that can be accessed for each mask card is checked outside the mask card to be accessed, and this check is performed on the common path. This is extremely superior in terms of certainty than self-diagnosis within the mask card.

According to the present invention (2), the following effects are remarkable: (1) Preventing destruction and erroneous output of memory data outside a predetermined area; (2) Treating memory data outside a predetermined area as data in the correct area. (3) It is possible to disconnect the mask card from the system by detecting an abnormality. (4) History management of defective data makes it easier to replace frequently defective cards with spare parts during regular system inspections. (5) Improving the reliability of the system by removing defective mask cards and reconfiguring the system, such as removing mask cards with low frequency of defects and switching to spare masks or one card or two.

[Brief explanation of drawings]

Fig. 1 shows an example of the system configuration and common bus of a conventional multi-mask system, Fig. 2 shows the first embodiment of the present invention, Fig. 6 shows an operation chart for reading data from a slave card, and Fig. 4 shows an example of the system configuration and common bus of a conventional multi-mask system.
The figure is a slave card pig write operation chart, No. 5.
The figure is an operation chart when accessing outside the area in the first implementation, and FIG. 6 is a diagram. Second Embodiment of the Invention FIG. 7 is an operation chart of the second embodiment during out-of-area access. 1...Pass control card, 21.2-2...Mustard, 3-1.3-2...Memory card, 4-1.4-
1...I/O card, 5...Address input gate,
61 to 6-6...Mask card number reading while bus is in use, 7...Strobe reading game while bus is being accessed.8.
・・Area address registration memory, 9-1 to 9-3...-
10.11...Address size discriminator, 12...
Now, 13-1.13-2.13-3...Gate, 1
4 differentiating circuit, 15...access confirmation return signal storage block, 16...CPU, B...common bus, A
AT2F part, D...Data part, CS...Control signal part BC...Bus right control signal part, CC...Common lock part.

Claims (2)

[Claims] (1) In a multi-mask system including a plurality of mask cards and a slave card that can be accessed in common by the plurality of mask cards, the address signal and mask card number that are accessed outside the mask card that accesses the slave card are means for monitoring, means for storing an address of an area that may be accessed for each master card, and comparing the size of both the address signal to be accessed and the area address to determine whether or not it is within the area. A multi-mask system comprising a means for determining a path, identifies a mask card using a path on a common path, and checks an address on the common path to prevent access outside the area. - Accidental access protection method. (2) In a multi-mask system that includes multiple mask cards and slave cards that can be commonly accessed by the multiple mask cards, monitor address signals and mask card numbers that are accessed outside the mask card that accesses the slave cards. means for storing an area address that may be accessed for each master card;
means for comparing the size of the address signal to be accessed and the area address to determine whether or not it is within the area; means for locking the access confirmation return signal of the slave card; and means for locking the access confirmation return signal of the slave card; It is equipped with means for outputting on behalf of the user, and means for reading and storing the address data and mask card number determined to be incorrect, and identifying the mask card using the pass on the common path, and A false access protection method in a multi-mask system characterized by checking addresses to prevent out-of-area accesses.