JPS6261974B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control memory history method, and more particularly to a control memory history method for checking the history of whether or not a microprogram written in a control memory has been used.

A microprogram is stored in the control memory, and the data processing device performs various control operations based on this microprogram when performing its operations. Since these microprograms exist corresponding to many types of macro instructions, there are also many types of microprograms, and each microprogram is composed of many steps or branches depending on conditions. The branch destination also consists of a large number of steps. Therefore, if a microprogram that is not used for some reason is written in the control memory, that control memory is not being used effectively. Furthermore, if there is a microprogram that is not used in the control memory, there is no track record that that part has operated correctly, and there is a high possibility that a program error will exist in that part.
Therefore, although it is desired to check whether the microprogram written in the control memory is being used, it has not been possible to do this by simple means in the past. Therefore, it is highly desirable to detect by simple means whether a microprogram in a control memory has been used.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a control memory history method that detects by simple means whether or not a microprogram in a control memory has been used. The control memory history method detects the usage status of the microprogram written in the control memory.
1 in the microprogram input to the control memory
1-bit error generating means for generating a bit error; reading means for reading a microprogram written in a control memory; and detecting and correcting a 1-bit error when it exists in the microprogram read from the control memory. Provided with an error detection/correction means and a history detection means for detecting the address of the microprogram where the error detected by the error detection/correction means existed,
The error status of the microprogram read during test control is reversed and written to the control memory again, and after the test is finished, the microprogram stored in the control memory is read and the address where the error exists. The present invention is characterized in that it is determined whether or not the microprogram is used by detecting the above.

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows the configuration of an embodiment of the present invention, in which 1 is a control memory, 2 is an address register, 3 is an output register of the control memory, 4 is an error detection/correction circuit, 5 is a control register, and 6 is a control memory. This is a history detection section.

The control memory 1 is a memory in which a microprogram for controlling a processor (not shown) is written, for example, a rewritable random program.
Consists of access memory. This control memory 1 contains a microprogram entry section 1-0 and an ECC code (SECDED) for error checking.
The correction code entry section 1-1 includes a correction code entry section 1-1 in which a code is entered.

Address register 2 is a register in which an address for accessing control memory 1 is set. The output register 3 is a register in which data (microprogram and ECC code) read from the control memory 1 is temporarily set.
The error detection/correction circuit 4 detects and corrects a 1-bit error when there is a 1-bit error in the data read from the control memory 1, and detects this 2-bit error when a 2-bit error exists. This is a circuit that does this.
The control register 5 is a register in which a microprogram read from the control memory 1 is set, and based on the microprogram set in this register, control signals are transmitted to each part of the data processing device, thereby performing the desired control. is to be carried out.

The history detection section 6 identifies whether or not the microprogram written in the control memory 1 has been used.

Next, a method for detecting the use of a microprogram will be explained in detail based on FIG.

First, a microprogram previously stored in the control memory 1 from an external storage such as a magnetic disk device (not shown) is written. In this case, a 1-bit error is forcibly generated in all microprograms written in the control memory 1 based on a 1-bit error generation part (not shown).
Fill in along with the ECC code. Thus, in the control memory 1, a microprogram with a 1-bit error is stored in the microprogram entry section 1-0.
and the correct ECC code is entered in the correction code entry section 1-1.

To perform test control in this state, a test address is set in address register 2. Based on the address set in address register 2, the microprogram is read out from control memory 1 along with its ECC code and temporarily held in output register 3. These microprograms and ECC codes are then transmitted to the error detection/correction circuit 4. At this time, since there is a 1-bit error in the microprogram as described above, this error is corrected based on the ECC code and output to the control register 5, and various controls are performed based on this.
The correct corrected microprogram output from this error detection/correction circuit 4 is then
It will be rewritten in the control memory 1 along with the ECC code. Next, address register 2 is
For example, the address signal is incremented by 1 and set by a +1 counter (not shown), and based on this, the next microprogram is set in the output register 3 from the control memory 1 together with the ECC code. Since this microprogram similarly includes a 1-bit error, it is corrected by the error detection/correction circuit 4 and then rewritten in the control memory 1. The microprogram read out for test control in this way is in a state where the 1-bit error that was forcibly generated when the microprogram was written into the control memory 1 has been corrected, and it has become a complete microprogram. The data is rewritten in the control memory 1.

Therefore, after a series of tests are completed, all the contents of the control memory 1 are read out, a microprogram in which a 1-bit error exists is detected by the error detection/correction circuit 4, and this detection signal is sent to the history detection section 6. to communicate. At this time, since the address of the microprogram in which the 1-bit error exists is transmitted to the history detection section 6 from the address register 2, it is possible to detect which microprogram is unused.

Another embodiment of the present invention will be described based on FIG.

In FIG. 2, the control memory 1 initially contains 1
A correct microprogram with no bit errors is written along with its ECC code in the microprogram entry section 1-0 and the correction code entry section 1-1, respectively. Then, when the test address is set in address register 2, the microprogram and ECC code are read out from control memory 1 based on this address, and these are passed through output register 3 and error detection/correction circuit 4. and is set in the microprogram output register 7. Of these, the microprogram portion is output to the control register 5, and various controls are performed based on this. On the other hand, the microprogram and ECC code set in the microprogram output register 7 are transmitted to the 1-bit error generation circuit 8, and after a 1-bit error is forcibly generated in the microprogram portion, the correct ECC code is output. The information is also rewritten in the control memory 1. Therefore, in the case shown in Fig. 2, the control memory 1 is
will be re-entered. Of course, when a microprogram that has been read once by a test program is read again, the 1-bit error is corrected by the error detection/correction circuit 4 and then set in the microprogram output register 7, so that it is correct. Control will be performed based on microprograms. After a series of tests are completed in this manner, the contents of the control memory 1 are read out completely, an accurate microprogram is detected by the error detection/correction circuit 4, and this detection signal is transmitted to the history detection section 6. At this time, the history detecting section 6 is informed from the address register 2 of the address where the correct microprogram is written, so that it is possible to detect which microprogram is unused. Of course, the same effect can be obtained by configuring the error detection/correction circuit 4 to output an output when a 1-bit error is detected, as in the case of FIG. 1 above, and transmitting this output to the history detection section 6 via an inverter. be. Further, the 1-bit error generation circuit 8 does not normally perform 1-bit error control, but performs the 1-bit error generation operation as described above when the debug mode signal "1" is applied for history investigation. be.

As explained above, according to the present invention, the usage state of the microprogram written in the control memory, that is, the history of the control memory, can be stored without increasing the capacity of the control memory or particularly lengthening the execution time. It can be investigated using extremely simple means.

Here, the failure rate when a 1-bit error actually occurs is sufficiently long compared to the common debugging period, so in this method, by constantly writing data to the control memory, the occurrence of so-called temporary 1-bit errors can be ignored. can do. Only burst errors pose a problem, but since this has a negligible failure rate, the present invention allows the history of the control memory to be investigated accurately and extremely easily.

[Brief explanation of the drawing]

FIG. 1 shows the configuration of one embodiment of the present invention, and FIG. 2 shows the configuration of another embodiment of the present invention. In the figure, 1 is a control memory, 2 is an address register, 3 is an output register, 4 is an error detection/correction circuit, 5 is a control register, 6 is a history detection section,
Reference numeral 7 indicates a microprogram output register, and reference numeral 8 indicates a 1-bit error generation circuit.

Claims (1)

[Scope of Claims] 1. A control storage history method for detecting the usage status of a microprogram written in a control memory, comprising a 1-bit error generating means for causing a 1-bit error in a microprogram input to the control memory; reading means for reading out the microprogram written in the control memory; error detection/correction means for detecting and correcting a 1-bit error when it exists in the microprogram read from the control memory; A history detection means is provided to detect the address of the microprogram in which the error detected by the correction means exists, and the error status of the microprogram read during test control is reversed to the state before reading, and the control memory is read again. A control memory history method characterized in that, after the test is completed, the microprogram stored in the control memory is read out and an address where an error exists is detected to determine whether or not the microprogram is used. .