FR2659763A1 - COMPUTER SYSTEM, PROGRAM SOURCE AND METHOD FOR SELECTIVE VALIDATION OF FUNCTIONS IN SUCH A COMPUTER SYSTEM. - Google Patents

Abstract

This system comprises a removable program source (9,12,14), memory means (3,9) for storing program instructions; a central processing unit CPU (1) for executing stored program instructions, means (2) for issuing characteristics, and means for validating access to access at least one characteristic and comprising means for comparing a sequence of bytes output from the CPU in response to instructions, to a reference sequence of bytes, and to validate characteristics based on the result of the comparison. Application in particular to computers receiving their program from a removable program source.

Description

The present invention relates to computer systems, in particular

a computer that receives its

  software program from an amo-

  such as a ROM cartridge, a floppy disk, or a cassette tape. According to standard practice, a computer is designed and manufactured by a hardware company, while the software for that computer is written and sold by many different companies.

  This software can include many applications

  various cations, can be produced by a wide range

  competing vendors and may be available under different

  information formats including tape

  in cassette, the floppy disk and the ROM cartridge.

  In such circumstances, the seller of equipment, who

  the computer, may not be able to regulate or control the quality or appropriateness of such

  However, it seeks to ensure that any changes

  The design and manufacturing process provided to the computer does not make it incompatible with the software.

  written for previous generations of this same ordina-

tor.

  It can often happen that the manufacturer obtains

  maintain desirable reductions in the cost of manufacture or increase the reliability of the product by incorporating the most

  recent technological progress without affecting the compatibility

  with earlier generations of Cepen-

  However, such changes can not affect the characteristics of the computer, such as the number of display modes or the production systems.

of music and sounds.

  However, the computer manufacturer may

  improve your computer by adding features

  improved methods, such as

  additional display systems or new production systems.

  sound and music, while retaining the characteristics

  previously available characteristics and also by keeping the accounts with previous generations

of software.

  In such a case, the computer designer should know that his computer should work properly first with improved software that was written based on the new and improved features and was specifically designed to use them, and secondly

  with old software that was written without the knowledge of

  new and improved features in particular.

  In particular, the computer designer must ensure that old software does not inadvertently activate

  new features The computer requires a

  granted that the new characteristics

  are available only for the new software.

  heaven that was written with a complete understanding of the

  correct use of these new features.

  ticks. Previously, computer manufacturers have sometimes published specifications for their products indicating that certain areas of the I / O system and the memory card are reserved for future expansion or enhancement. of

  Such areas have not been reserved.

  Similarly, some computer manufacturers

  to improve their products have previously sought to control the quality or appropriateness of a third party's software, for example by publishing appropriate software listings. Such a process only applies when the number of software titles to be qualified is

  known and has low value by allowing

easy way.

  Similarly, some computer manufacturers have previously insisted that the software

  to be used with the new and improved characteristics

  must be equipped with a hardware code, known by

  elsewhere under the term "dongle", that is, electronic key

  Such a process involves the expenditure first of a qualification of the software for the control of its appropriate character and for its use with the new computer, and second, the expense of mounting a hardware code or "dongle" for each element of the software sold.

  In US Pat. No. 4,462,076 a system is proposed.

  which identifies a removable cartridge by requiring the CPU to read and control

  the contents of selected locations in the cartridge.

  A similar solution is used in the Commodore 64 computer system, see Commodore 64 Programmer's Reference Guide, 1982, Commodore Business Machines Inc, page 263 Such proposals require the computer to have a special software package (eg ROM software). ) allowing him to search for the code

authentication.

  European patent specification 67 875 and the patent

  No. 4,688,169 both disclose systems in which machine-specific code or "signature" is written on each copy of a program so that it operates only on a specific machine identified by that code or this signature Again, it is necessary that the microprocessor controls this particular location of

the band of the program.

  In another case, the patent specifications

  206 704 and 217 668 describe a cartridge of

  ROM which contains its own microprocessor so that the output signal of this microprocessor can be compared to that of a corresponding device located in

  the main computer for the identification of the car-

  However, providing a microprocessor in the ROM cartridge is both expensive and complex. In accordance with the present invention, it is

  provided a computer system characterized in that it com-

  takes: a removable program source, suitable for insertion; memory means for storing instructions

  program; a central processing unit for executing

  storing stored program instructions; means of

  delivery of characteristics, which contain characteristics

  characteristics to which access is obtained by means of instructions from the CPU unit; and means of

  validation of access to validate access to at least

  born of characteristics; the access validation means comprising means for comparing a sequence of bytes, delivered by the CPU unit in response to the program instructions, to a byte reference sequence, and for validating the selected features in the means of delivery of characteristics, depending on the result

of the comparison.

  In accordance with the present invention, the

  gram itself causes the CPU to output a sequence of bytes. Only then, when the sequence thus produced conforms to the reference sequence, are the additional features perfected.

  made available to the program.

  The invention also provides a source of

  gram, such as a ROM cartridge, etc., for use in a computer system, and a method for selectively validating

  functions in a computer system.

  The present invention has the advantage of being simple to implement, requiring only that,

  under the control of the software, the processor saves them.

  predetermined sequences of values at a location of

  specified port for the provision of the characteristics

  improved ticks No special software packages incorporated,

  may be necessary in computers that are

  singing "security codes" to specific addresses

  in the program source is not necessary.

  separate processor is required in the program source.

  Other features and advantages of the pre-

  invention will emerge from the description given below.

  after referring to the accompanying drawings, in which: Figure 1 is a block diagram of a computer system according to the invention; FIG. 2 is a block diagram illustrating a

  blocking circuit located in the production chip.

  video / sound of the system of Figure 1; FIG. 3 is a flowchart illustrating the steps taken in a successful release test of the new improved features in the computer; FIG. 4 is a flowchart illustrating the steps implemented during an unsuccessful attempt to unblock the new characteristics; and Figure 5 is a flowchart illustrating the

  not implemented in a combined test of blocking new

characteristics.

  FIG. 1 represents a computer comprising a CPU 1 (central processing unit), which executes

  instructions from the application software, ac-

  loaded This software is loaded through

  25 of a bus 25 in a random access memory (RAM) 3 and can come from a ROM memory cartridge 9 (read only memory) connected to the bus of the CPU unit by

  via a connector 8 of the media cartridge

  ROM, or a floppy disk 12, whose contents are read through a diskette drive 11 and a floppy disk controller 10; or a tape 14 inserted in a cassette and whose contents are read through a cassette tape drive 13 Although particularly suitable for use with a ROM cartridge, the present invention 'is not

  limited to a particular software loading method.

  When the program is located on a disk or tape,

  it is introduced in the RAM memory This operating mode

  is also possible when the program is

  killed in a ROM cartridge, although it is

  that the CPU unit executes one by one the instruc-

  directly from the cartridge.

  following description, it is assumed that the program is

  troduced into RAM, which is applicable to all three

types of program sources.

  The CPU executes the instructions during the normal course of the current software, these instructions causing the reading and recording of the contents of the RAM 3, the reading of the state of a keyboard 7 and the reading and recording internal registers and a memory in a video / sound production chip 2 which controls the video and acoustic characteristics of the computer. These internal registers and this memory are

  units associated with the order of the old characters

  basic characteristics or features, and also

  additional units associated with the new features

  characteristics or characteristics The characteristics

  basic ticks are available at all programs but

  advanced features are available uniquely

  Written programs with specific authorization for these advanced features The microchip 2

  also establishes the communication path for the

  7 and the RAM 3 inside the bus 25.

  Similarly, the production chip

  deo / sound 2 contains a blocking circuit that prevents a

  old software does not accidentally activate new

  This blocking circuit has two states.

  When blocked, the new improved features are not accessible for the CPU unit and when unlocked, these features are available. Figure 2 shows the details of the circuit of

  blocking inside a production chip.

  video / sound This circuit includes a se-

  pseudo-random bit sequences (PRBS) consisting of bistable flip-flops 15 to 22 and the exclusive-OR gates associated therewith Bistable flip-flops 15 to 22

  operate in practice in the form of two genera-

  PRBS, each four-bit wide, which

  wind to deliver a pseudo-random binary sequence PRBS

  eight-bit wide width The arrangement of a gen-

  The PRBS generator is well known and basically comprises a shift register having a number of stages, four as shown, the selected stage output signals being combined and returned as an input signal to the first stage. PRBS

  can take sixteen different states including

  Zeros only Each state has a unique 8-bit value in the PRBS bus (7: 0). The sixteen states are designated PRBS (O) to PRBS (15).

  this is well known in the PRBS generators, if one de-

  sign by n_ the number of stages of the register, the generator PRBS is able to produce a pseudo-random sequence of O and 1 The sequence is repeated with a length which,

  provided that the connections to the doors are correct-

  chosen, is not more than m_ = 2 n-1.

  The state of the blocking circuit is determined by the flip-flop 24 with the output signal ENF.

  the output signal NFE is equal to zero, the characteristics

  improved issues are invalidated (blocked) When the

  ENF is equal to one, the improved features are validated and are available for the CPU unit (they

are unlocked).

  The state of the PRBS generator advances each time the CPU executes an output instruction sent to the

  port A, which is a port located in the microchip vi-

  deo / son 2, by means of which the blocking circuit is connected

  bus 25, so that an exit instruction

  port A is an exit instruction sent to the

  blocking circuit Such an output instruction pro-

  in the CP signal line, an im-

  impulse which controls in a rhythmic way the eight flip-flops

  bistables 15 to 22 which are the generator PRBS.

  During the existence of the rising (active) edge of this pulse, the data of the CPU unit appears in the DI bus (7: 0) and is compared to the PRBS (7: 0) state of the PRBS generator in a comparator. 23 to 8 bits

  for example, if the value PRBS (7: 0) is equal to 3 F (in

  hexadecimal level) and if the CPU unit performs an instruction

  delivering a data value of 3 F (notarized

  hexadecimal) at port A, the state of the PRBS generator increases

  the output signal of the comparator 23 indicating a

successful comparison.

  When each positive edge of the clock pulse (CF) appears, the generator PRBS: a) is advanced in its sequence, if the data present in the line DI (7: 0) coincide with the state PRBS (7: 0) PRBS generator, b) only positions 1, that is to say restart the sequence from the beginning if the comparator indicates that the data (7: 0) present in

  DI is not identical to PRBS (7: 0).

  When each positive edge of the clock pulse (CP) appears, the output bistable flip-flop a) goes to a state O (blocked), if the value PRBS is in the state PRBS 14, b) goes to state 1 (unlocked), if the value PRBS is in state PRBS 15,

  (c) maintain its previous state.

  The output signal of the CPU unit depends on

  This program is taken from the program source, namely the ROM 9, the diskette drive 12, or the cassette tape 14.

  Therefore, the computer can indicate, by means of

  previously described, if the software in the ROM, diskette, or tape has been

  written with the improved features or not These

  characteristics are released only if it has been written with these improved features in memory, so

  that these characteristics are made available to the

  As a result, the software, which was written before

  the appearance of the improved characteristics, can not

  inadvertently peel or alter these.

  Whenever it is necessary to

  the blocking circuit and the state of the generator

  PRBS is unknown, the generator must be synchronized

  first by means of the positioning of only 1, then by the positioning of only 0

  causes the PRBS generator to be reset.

  FIGS. 3, 4 and 5 show sequences of output data values of the CPU unit enabling activation of the blocking circuit. These figures are self-explanatory and that is why they will not be described. right here

  Figure 3 is a global flowchart

  the steps taken in a successful test of

  FIG. 4 is a flow chart showing the steps taken in an unsuccessful blocking or unblocking of the improved characteristics FIG. 5 is a flowchart illustrating the steps implemented during a successful blocking test. FIG. of the

  new features The blocks shown contain

  hexadecimal values to be recorded at port A. Similarly, PRBS (0-15) represents the states

PRBS in order.

  Therefore, we see that the system has two parts The first part is a blocking software mechanism, which compares recorded data values

  by the CPU unit at port A, in the state of a genera-

  PRBS, and the second part is a logic subprogram.

  sky sending the correct sequence of data values

  PRBS (0-15) at port A This deliberate choice is made

  number of values so that it is sufficiently

  cure for that probability that an old active software

  accidentally the code is weak enough to be neglected

  This software can be implemented in many different forms; it may for example contain a series of output instructions to each of which is associated a data operand corresponding to the PRBS state;

  otherwise, it may include a loop to which is associated

a look-up table.

  The system described does not require a command

  detailed information from the computer manufacturer,

  sky to be used in this system and does not require

  the use of an electronic key or the like.

  The invention can be used in the case where no reserva-

  zones of the input / output system of the

memory has not been executed.

  The invention is not limited to a local technique

  software or to a particular program structure, but applies to any software capable of delivering the correct sequence of data values.

  Moreover, the invention is not limited to a particular support

  bind information for memorizing the program and in particular is applicable to the use of a cartridge

  ROM, floppy disk, or tape.

Claims (8)

  1 computer system, characterized in that it comprises a removable program source (9, 12, 14), able to be inserted; memory means (3, 9) for storing program instructions; a CPU (1) CPU for executing stored program instructions; feature delivery means (2), which contains features to which access is obtained by means of instructions from the CPU; and access validation means (PRBS) for enabling access to at least one of the selected features;   the access validation means (PRBS) comprises   means (23) for comparing a sequence of bytes, delivered by the CPU in response to program instructions, to a byte reference sequence, and for validating selected features in the feature delivery means, depending on the result of the comparison.   Computer system according to claim 1,   wherein the program source (9) comprises a car- ROM memory key.   Computer system according to Claim 2, characterized in that the memory means - (3, 9) consist at least in part of the memory cartridge.   ROM (9), and that the unit (CPU) directly executes   tructions contained in the memory cartridge.   Computer system according to claim 1, characterized in that the program source comprises a floppy disk (12).   Computer system according to claim 1, characterized in that the program source comprises a cassette tape (14).   6 Computer system according to any one of   claims 2, 4 and 5, characterized in that the   memory means (3, 9) include a memory (9) with   for the CPU unit and not located in the source of pro-   gram removable, and that it is further provided charging means for loading a program, located in the program source, in the memory for its execution by the CPU unit.   7 Computer system according to any one of   Claims 1 to 6, characterized in that the means   Access Validation Methods (PRBS) include a pseudo-random bit sequence generator used to produce the byte reference sequence.   8 Removable program source intended to be   used in a system according to any one of the   1 to 7, characterized in that it includes means for causing the CPU to execute program instructions such as, for example, outputting a sequence of bytes to compare it to said reference sequence.   in said access validation means (PRBS).   Method for selectively validating functions in a computer system comprising a unit   CPU (1), characterized in that it includes the steps of   both to connect a removable program source (9, 12, 14), which can be inserted, to a computer system, to execute instructions stored in the CPU (1) so as to output a sequence of bytes, compare the   sequence thus delivered from bytes to a reference sequence   bytes, and selectively enable CPU (1) access to selected   operation according to the results of the comparison.   Method according to claim 9, characterized in that the reference sequence comprises a sequence pseudo-random binary.