JPS6238745B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a microprogram control device that improves the reliability of control storage using volatile semiconductor devices.

Programming microinstructions has advantages such as regularity and speeding up of processing, and is therefore widely used in information processing devices, from central processing units, various control devices, to terminal devices. Generally, microprograms are stored in a storage device called a control storage, and are sequentially read out and executed when desired. When storing information in the control storage, redundant bits such as Hamming codes are added to information such as programs to provide a correction function and improve reliability.

In that case, what is normally done is to correct a 1-bit error to make the information error-free, and if a 2-bit error is detected, a retry is performed, and if it is still defective, the operation is stopped and an alarm is issued. Furthermore, using a volatile semiconductor element as a control storage is advantageous from the viewpoint of cost and storage capacity. Although the degree of integration of semiconductor devices is increasing year by year, it has been found that the following phenomenon frequently occurs when used for control storage. Even if the check immediately after performing a memory operation on the control storage is normal, it may change from "1" to "0" due to some reason, and this can be detected as a bit error. If you rewrite it as “1”, it will become “1” from now on.
This means maintaining a normal state without changing. This phenomenon is not caused by the fact that the semiconductor element is defective from the time of manufacture, but is thought to be caused by disturbances caused by natural phenomena such as strong or long exposure to ultraviolet rays. No means have yet been found to effectively deal with such phenomena.

The object of the present invention is to improve the above-mentioned drawbacks, and to provide a microprogram control system that rewrites the control storage by detecting the number of times when bit errors in the control storage are detected and corrected, thereby improving reliability during use. The goal is to provide equipment.

Embodiments of the present invention shown in the drawings will be described below. In the drawings, CST is a control storage using a semiconductor element, MPG is a device for reading and controlling a microprogram, and LDR is a loader, which is a control storage writing device. CNT is a counter, and AD is an AND operation circuit. loader
LDR is a device for writing microprograms stored on flexible disks, small magnetic tapes, etc. into control storage. Normally, when power is turned on to an information processing device, the power supply circuit is closed and started, and the specified The power supply circuit is configured to automatically open after a certain period of time. The control storage CRT, which has undergone the initial write operation at startup,
The microprogram is read out and executed when desired by the microprogram reading device MPG.
When read, error detection using redundant bits is always performed before passing to other control devices. When an error occurs due to a disturbance as described above, the control storage CST performs error correction, and the correction operation circuit EBC sends one pulse to the counter CNT each time. The counter CNT continues to count and when the count exceeds a preset count for the device, it issues an overflow signal OFS. Since the microprogram reading device MPG controls other devices using the program read from the control storage CST, it is confirmed by program analysis that no operation will occur in the near future for the control storage CST (in other words, the control storage When the register is in an idle state, that is, when it is detected that the read program is instructing the idle routine when entering the idle routine from the contents of the read program [as found from the next instruction address]), the logical AND operation is performed. Sends idle state signal WTS to circuit AD. Therefore, the output signal when the above-mentioned overflow signal OFS is ANDed with the idle state signal WTS becomes a restart signal for the loader LDR and is sent to the control storage.
Performs an operation to rewrite all the memory contents of CST. This operation updates the contents of the control storage CST in a short time, so if the program is read immediately after that, there will be no errors and processing and control operations will be performed immediately, and even if there are errors, they should be small. Because of this, normal 1-bit error correction is performed immediately.

In this way, even if an error occurs in the stored contents of the control storage according to the present invention due to disturbance, the device that detects the number of corrections using redundant bits will initiate a rewrite operation when the number of corrections reaches a predetermined number or more. Therefore, the storage contents of the control storage are always in a state where the occurrence of errors is reduced, improving the reliability of the stored contents. In addition, fewer error corrections are required when reading data, and control operations can be performed at higher speeds.Furthermore, large amounts of bit errors, such as 3-bit errors, are not overlooked and processed during information processing operations, making the processing results more reliable. It has the effect of increasing sex.

[Brief explanation of the drawing]

The drawing is a block diagram showing an embodiment of the present invention. CRT...Control storage, LDR...Writing device (loader), MPG...Microprogram readout control device, EBC...Error correction operation circuit, CNT...Counter, AD...AND operation circuit, WTS... Idle signal.

Claims (1)

[Scope of Claims] 1. A microprogram control device using a volatile control storage, wherein the control storage is provided with read information correction means, and the microprogram control device includes a microprogram write for the control storage. a device for counting the number of times errors have been detected and corrected in information read from the control storage; and a device for counting the number of times errors have been detected and corrected in information read from the control storage; A microprogram control device comprising: a device for restarting the microprogram writing device when the microprogram writing device is restarted.