JPS6344242A - Microprocessor - Google Patents

Abstract

PURPOSE:To prevent a program from being decoded and stolen, by constituting a system by building in an address conversion circuit being connected to a microprocessor chip, and a circuit which sets and fixes the converting function of the conversion circuit, with the microprocessor chip. CONSTITUTION:The address terminals A0-An of the microprocessor chip 11 are connected to an input part on one side of the exclusive OR circuits Ex0-Exn of the address conversion circuit 13, and the voltage of a level of 0, or of a level of 1, is supplied from a conversion function generation circuit 12 to the input part on the other side, and the chip 11, the circuits 12 and 13 are built in the microprocessor.

Description

[Detailed Description of the Invention] [Summary] By constructing a system in which an address conversion circuit for converting addresses is built in together with a microprocessor, and by connecting the converted address signal to an external storage device,
By preventing the address array in the external storage device from being decoded, the program stored in the storage device is prevented from being decoded and stolen.

[Industrial application field]

The present invention relates to improvements in microprocessors.

Microprocessors require programs and data to perform their functions. By specifying the address of the external storage device using these pieces of information 4, you can read from the continuous-exclusive storage device ROM or write to it at any time from the continuous-accessible storage device RA? I or other storage devices are used to write and continue.

Although microprocessors use address buses, data buses, and control signals when accessing storage devices, the programs stored in the storage devices are the most important components of the microprocessor system.

A program stored in a storage device is retrieved by specifying an address when necessary.

Therefore, if the address part or storage location is known, the program configuration can be known.

Since the secrecy of programs cannot be maintained with a storage device provided with simple addresses, it is desirable to provide a microprocessor with an address translation function.

[Conventional technology]

Conventionally, when a microprocessor accesses a storage device, as shown in FIG. 5, an address conversion circuit 3 is used which creates a complicated correspondence between the address terminals 0 to An of the ROM or RAM 2 and the address terminals AO to An of the microprocessor.
There are some devices that are connected using a computer to make it difficult to decipher the program in the storage device 2. This conversion circuit means is realized by providing connection lines such as connecting 0 to the address terminal of the microprocessor, for example, to the address terminal All of the storage device, and connecting the address terminal Δ1 to the address terminal A5 of the storage device.

Complex address conversion can be performed by changing the direction of attachment of such connection lines.

[Problem that the invention seeks to solve]

However, in the case of the above-mentioned conventional means, the address terminals AO to An of the tQ device can be easily inspected from the outside, where the address terminals AO of the microprocessor 1 are written as An, and therefore the address conversion rules are easily determined. The problem is that the program can be decoded by a third party and imitated and modified.

[Means for solving problems]

The above problem is solved by converting the address conversion circuit n of the microprocessor chip 11, as shown in the principle diagram of the present invention in FIG.
Address conversion circuit 1 that connects directly to external storage device 2
3 and a conversion function creation circuit 12 capable of changing and fixing the conversion function of the conversion circuit 13 are incorporated together with the microprocessor chip 1 as a single system.

[Effect]

In the microprocessor of the present invention, the address terminal is converted by the internal conversion circuit 13 and sent to the address terminal for the external storage device 2 of the microprocessor.
The already converted address is output to and directly connected to the external storage device 2. Furthermore, since the conversion circuit 13 is built into the system together with the microprocessor chip 11, it is impossible to check the input terminal and output terminal of the conversion circuit 13, thereby preventing the address conversion rule from being detected.

According to the present invention, the conversion function creation circuit 12 and the conversion circuit 13 are made small and together with a microprocessor chip, for example,
It can be sealed in the same puff cage, and the address conversion rule can be configured and given in advance before being housed in the puff cage, or can be arbitrarily specified and fixed from the outside after configuring the built-in system.

〔Example〕

The present invention will be described in detail below according to the illustrated embodiments.

FIG. 2 is a block circuit diagram of a microprocessor according to an embodiment of the present invention.

In the illustrated embodiment, the address conversion circuit 13 includes a number of exclusive OR circuits Eχ0 to EXn corresponding to the address lines. Supplied with voltage. Further, the outputs of 0 to An to the address terminals of the microprocessor chip 11 are supplied to the other input section of each exclusive OR circuit.

As is well known, in the exclusive OR circuit, when one input is fixed at the "O" level, the output signal is at the same level as the other input level. Further, when the single power is fixed at the "1" level, the output section outputs a signal having a level that is an inversion of the other input level.

Since the conversion function creation circuit 12 of the illustrated embodiment supplies fixed level inputs to each of the exclusive OR circuits ExO to Exn, by selecting and fixing the levels, the level of the address line supplied to the other input section is converted as appropriate. Let me AO'
~An' is output.

Now, assume that it is 1w7 and the address is expressed in hexadecimal. When the conversion function creation circuit 12 supplies alternately fixed "1" level and °0 level to the exclusive OR circuit of the conversion circuit connected to adjacent address terminals of the microprocessor chip 11, the The address specified by address line AO-A7 is the third
As shown in the table of the figure, the output part address terminals AO'' to A7° of the conversion circuit 13 are converted to different addresses.

For example, address 02 at the address terminal of the microprocessor chip 11 is converted to address 54 at the output address terminal of the conversion circuit 13, and address FD is converted to address A8.

An embodiment of the conversion function creation circuit 12 is shown in FIG.

In the figure, PAO to PAn are terminals that apply a fixed input voltage to the exclusive OR circuit of the address conversion circuit 13.

RO to Rn are resistors that supply level "1" from the V+ power source to one input portion of the exclusive OR circuit.

On the other hand, circuit elements FO+DO~Fn, On are PAO
~Give earth level “0” to the PAn terminal.

Here, FO to Fn are nichrome fuses. This fuse is an element that can be used to realize a programmable logic element that is integrated on a large scale.

Initially, the PAO"PAn terminals are connected to the ground through diodes Do-Dn, and simply connecting the conversion function creation circuit 12 to the address conversion circuit 13 does not change the address of the microprocessor chip 11. It is output to the outside from terminals AO° to An'.

By the way, a signal is applied to the transistor TRO=TRn from the terminals -AO to WAn via the buffer amplifier BO=Bn, and a large current is instantaneously applied to the diode DO=D from the power source 4T.
For example, the diode DO=Dn with nichrome fuses FO to Fn is in the oven state.

For this reason, the connection with the earth is cut off, and the PAO"PAn terminal is connected to the voltage of the power supply ■+, that is, "1" via the resistor RO"Rn.
``Fixed to level.

The conversion function creation circuit 12 includes an exclusive OR circuit connected to each address terminal and functioning as an inverter or a buffer.

The "1" level signal applied to the address conversion circuit 13 inverts the signal level applied from the microprocessor chip 11 to convert the address.

〔Effect of the invention〕

As described above, the present invention converts an address into an undecipherable address using a simple circuit configuration, thereby making it possible to prevent a third party from stealing and imitating a program stored in a storage device. The effect is extremely large.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of the present invention. FIG. 2 is a block circuit diagram of an embodiment of the microprocessor of the present invention. FIG. 3 is an address conversion table in an embodiment of the address conversion circuit. FIG. 4 is a diagram of the present invention. FIG. 5 is a circuit diagram of an embodiment of a conversion function creation circuit. FIG. 5 is a connection diagram of a conventional address conversion circuit. In the figure, 1 is a microprocessor, 2 is 1. α device, 3 is a conversion circuit, 11 is a microprocessor chip, 12 is a conversion function creation circuit, and 13 is an address conversion circuit. Fig. 3 Variation I of the present invention (deception, in Russian) Fig. 4

Claims (1)

[Claims] An address conversion circuit (13) connected to the address terminal of the microprocessor chip (11) and a conversion function creation circuit (12) for setting and fixing the conversion function of the address conversion circuit (13) are built in together with the microprocessor chip (11). A microprocessor characterized in that it is configured to configure an integrated system.