GB2092338A - Improvements relating to programmable memories - Google Patents

Abstract

An electronic memory device is packaged in a single chip with a microprocessor. A program is entered the memory and checked. Thereupon a signal is generated, perhaps by the logic on the chip itself, which physically destroys the access path to the memory directly from outside the chip. The memory remains in communication with the microprocessor.

Description

SPECIFICATION Improvements relating to programmable memories This invention relates to programmable memories.

A program entered in a memory is often a valuable piece of 'software', but buthitherto there has been no satisfactory way of protecting it, legally or physically. Most memories have means for checking that they have been programmed correctly, but in providing this facility it opens the door for others to extract the program. It is the aim of this invention to prevent this.

According to one aspect of the present invention there is provided a memory in chip form in which external access to a program stored therein is physically disconnectable within the chip by a signal generated subsequent to the entry and checking of the program.

According to another aspect of the present invention there is provided a method of protecting software, comprising programming an electrode device in chip form, checking that program, and generating a signal which physically disconnects, within the chip, external access to the program.

By chip form is meant any packaged electronic device where at least some of the components are inaccessible without physical destruction of the package.

This technique is intended particularly for EPROMs, and there is now available a microprocessorwith an EPROM all on a single chip to which it should be well suited. Having entered the program and checked it via a test pin, at the end of the test sequence the logic on the chip itself can be arranged to "blow a fuse" in the access path to the program.

The latter is therefore securely trapped in the chip, accessible only to the microprocessor.

This has general application, but our preferred use is in the field of electronically controlled games, particularly fruit machines and video games.

CLAIMS (filed 29.1.82) 1. A memory in chip form in which external access to a program stored therein is physically disconnectable within the chip by a signal generated subsequent to the entry and checking of the program.

2. A memory as claimed in claim 1, in combination with a microprocessor on a single chip.

3. A gaming or amusement with prizes machine controlled by a microprocessor with a programmed memory in combination as claimed in claim 2.

4. A method of protecting software, comprising a programmed electronic device in chip form, checking that program and generating a signal which physically disconnects, within the chip external access to the programme.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements relating to programmable memories This invention relates to programmable memories. A program entered in a memory is often a valuable piece of 'software', but buthitherto there has been no satisfactory way of protecting it, legally or physically. Most memories have means for checking that they have been programmed correctly, but in providing this facility it opens the door for others to extract the program. It is the aim of this invention to prevent this. According to one aspect of the present invention there is provided a memory in chip form in which external access to a program stored therein is physically disconnectable within the chip by a signal generated subsequent to the entry and checking of the program. According to another aspect of the present invention there is provided a method of protecting software, comprising programming an electrode device in chip form, checking that program, and generating a signal which physically disconnects, within the chip, external access to the program. By chip form is meant any packaged electronic device where at least some of the components are inaccessible without physical destruction of the package. This technique is intended particularly for EPROMs, and there is now available a microprocessorwith an EPROM all on a single chip to which it should be well suited. Having entered the program and checked it via a test pin, at the end of the test sequence the logic on the chip itself can be arranged to "blow a fuse" in the access path to the program. The latter is therefore securely trapped in the chip, accessible only to the microprocessor. This has general application, but our preferred use is in the field of electronically controlled games, particularly fruit machines and video games. CLAIMS (filed 29.1.82)

1. A memory in chip form in which external access to a program stored therein is physically disconnectable within the chip by a signal generated subsequent to the entry and checking of the program.

2. A memory as claimed in claim 1, in combination with a microprocessor on a single chip.

3. A gaming or amusement with prizes machine controlled by a microprocessor with a programmed memory in combination as claimed in claim 2.

4. A method of protecting software, comprising a programmed electronic device in chip form, checking that program and generating a signal which physically disconnects, within the chip external access to the programme.