JPH03228140A - Microprogram controller - Google Patents

Abstract

PURPOSE:To shorten the time for processing an instruction by executing only error correction in the case of detecting error while executing the instruction, and executing a write processing during an interval between instruction after the end of the instruction. CONSTITUTION:In the case of detecting the error of a microprogram word set to a read register 5, an error detection circuit 6 outputs an error signal 14 and sets an error state flag 12. When the error is detected, an error correction circuit 7 executes the error correction and the microprogram word where error is corrected is set to a write data register 11. The error state flag 12 is reset by an instruction end signal 13 and a write instruction signal 17 is outputted from a control circuit 8. Then, the error corrected microprogram word held in the write data register 11 is written into a control memory 3. Thus, since the write processing is executed during the interval between the instructions, the entire processing time can be shortened.

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a microprogram control device, and more particularly to an error handling method when an error occurs in data read from a control memory storing a microprogram. Prior Art A block diagram of a conventional microprogram control device of this type is shown in FIG. This device includes a control memory 3 for storing microprogram words, address registers 2 and 9 for holding their addresses, a read register 5 for holding microprogram words read from the control memory 3, and a read microprogram word. Selects the error detection circuit 6 and error correction circuit 7 that detect and correct word errors, the control circuit 8 that controls error processing, the write data register 9 that holds corrected data, and the manual address for the address register 2. A selector 4 selects input data to the read register 5, and a decoder 18 decodes data from the read register 5. To explain the series of operations associated with error handling as an example,
The microprogram word read from the control memory 3 by the address register 2 passes through the selector 4 and is set in the read register 5, and at the same time, the address output from the address register 2 is set in the address register 9. At the next timing, the error detection circuit 6 performs an error check on the microprogram word output from the read register 5. At this time, if there is no error detection, the microprogram word passes through the decoder 18 and controls various registers. However, in the error detection case, all registers related to the microprogram are held by the hold signal 16 output from the control circuit 8. Then, the error microprogram word is corrected by the error KT il (circuit 7, selected by the selector 4 by the error signal 16, and set in the read register 5. At the same time, the error correction microprogram word is written to the write data register 11). The address of the error microprogram word, which is set in the address register 9, is selected by the selector 1 in response to the select signal 15 output from the control circuit 8, and is set in the address register 2. From the next timing onward, the error correction microprogram word set in the write data register 11 is determined by the write instruction signal 17 output from the control circuit 8 and the address in the address register 2 which is the write address.
Write processing to the control memory 3 is performed. When this write process is completed, the hold signal 16 is released and the error-corrected microprogram word set in the read register 5 passes through the decoder 18 and controls various registers. A feature of the error processing control described above is that writing is performed in the microprogram language during instruction execution. In the conventional microprogram control device described above, all error microprogram words that occur during microprogram sequence control, that is, during instruction execution, are corrected and written to the control memory before microprogram control is started. . Therefore, write control for purposes other than microprogram control is always performed, resulting in useless control over instruction execution. OBJECTS OF THE INVENTION An object of the present invention is to provide a microprogram control device that does not reduce the execution efficiency of the instruction sequence even if an error occurs in the microprogram. Structure of the Invention A microprogram control device according to the present invention comprises a control memory for storing a microprogram, an error detection means for detecting errors in a microprogram word read from the control memory, and an error correction means for correcting the errors. a first holding means for holding the address of the microprogram word in which an error has occurred; a second holding means for holding the microprogram word after error correction; Control 1 for controlling writing of the microprogram word of the second holding means into the control memory according to the address of the first holding means;
It is characterized by including steps. Embodiments Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, and parts equivalent to those in FIG. 2 are designated by the same reference numerals. The microprogram control device in this embodiment includes a control memory 3 for storing microprogram words, address registers 2 and 9 for holding their addresses, a read register 5 for holding microprogram words to be read from the control memory 3, and a read register 5 for holding microprogram words to be read from the control memory 3. An error detection circuit 6 and an error correction circuit 7 detect and correct errors in microprogram words.
, a control circuit 8 that controls error handling operations, an error address register 10 that holds the address of the microprogram word where the error occurred, a write data register 11 that holds the corrected data, and an error status flag 12 that indicates that an error has occurred. , selector 1 for selecting a manual address to address register 2, selector 4 for selecting input data to read register 5. It consists of a decoder 18 that decodes the microprogram word in the read register 5. Referring to FIG. 1, the address of control memory 3 is set in address register 2, and one of the following three addresses is set by selector 1. In other words, 111! for the sequence operation of a general microprogram!
The start address, the address of the next step, which is a subfield of the microprogram word output from the read register 5 during sequence operation, and the error address for the write process to the control memory 3, which is performed after the occurrence of an error in the microprogram word. One of the three addresses including the write address output from the address register 1o is set in the address register 2 through the selector 1. In the read register 5, either the microprogram word read from the control memory 3 or the microprogram word whose error has been corrected by the error correction circuit 7 is set via the selector 4 when an error occurs in the microprogram word. Ru. The address output from the address register is set in the address register 9, and this address becomes the address of the microprogram word set in the read register 5. The error detection circuit 6 is a circuit that detects an error in the microprogram word set in the read register 5. When an error is detected, it outputs an error signal 14, sets an error status flag 12, and controls each register. are doing. When an error is detected in the microprogram word output from the read register 5, the error correction circuit 7 performs error correction, and the error corrected microprogram word is set in the write data register 11. As described above, the write data register 11 is a register that holds the microprogram word after error correction, and is always set by the error signal 14 every time an error is corrected. Further, if the error signal 14 is not issued, a hold state is entered. The error address register 10 always holds the address of the microprogram word held in the write data register 11, so the update timing is also the same as that of the write data register 11, and otherwise it is in a hold state. The error status flag 12 is a flag indicating that an error has been detected in the microprogram word, and is set by the error signal 14 output from the error detection circuit 6 as described above in the microprogram sequence operation in one instruction. , the instruction end signal 13 of the microprogram word indicating the end of the microprogram sequence operation (
(hereinafter referred to as EOP13). Therefore, if a microprogram word error is detected during one instruction, it remains set until the instruction ends. The control circuit 8 controls the error processing operation of the microprogram word using the EOP 13, the error signal 14, and the error status flag 12. It generates a select signal 15, a hold signal 16 for holding all registers related to microprogram instruction processing, and a write instruction signal 17 issued at the write timing of a microprogram word. Next, the operation of the embodiment shown in FIG. 1 will be explained step by step along the time chart 1 in FIG. 3. The series of operations shown in this time chart are A and B. There are three instructions in C, and the A instruction is AO→At (an→a
L) 2 steps, B instruction is BO-Bl -B2→B3
The C instruction consists of several steps: (bO→b1→b2→b3). In the A instruction, since no error is detected in both the AO-At steps, the microprogram word aO is read from the control memory 3 by the AO set in the address register 2 and set in the read register 5 in the TO step. Further, the address register 2 is set with AI, which is the address of the next step, and the address register 9 is set with A, which is the address of the microprogram word aO.
O is set. The instruction end signal "EOP" is output from the microprogram word aO held in the read register 5 at the TI step.
13'' is output, and at this time, no error is detected in aO, and the error signal 14 is not issued. Also, the error status flag 12 is in the OFF state because there is no error in the A command, so the control circuit 8 output select signal 15
Therefore, in step T2, BO, which is the starting address of the next instruction (B instruction), is set. At the same time, the microprogram word a1 is set in the read register 5 by the address AI of the final step of the A instruction, and AO is set in the address register 9. At the TI and T2 steps, the microprogram word aOa set in the read register 5

Since no error is detected in either of the two, they are each decoded by the decoder 18 and control various registers. At this time, since no error occurs in either the error address register]0 or the write data register 11, they are in a hold state. Next, the B instruction, which consists of four steps, will be explained. As described above, the startup address BO is set in the address register 2 at step T2. Next timing (T
In step 3), the microprogram word bO is set in the read register 5 from the control memory 3, BO is set in the address register 9, and the address B1 of the next step is set in the address register 2. Since there is no error in the microprogram word bO, in the next step (step T4), the read register 5 contains the microprogram word bl', the address register 9 contains the address B], and the address register 2
The address B2 of the next step is set respectively in . When the error detection circuit 6 detects an error in the microprogram word bl' at the next timing (T5 step),
An error signal 14 is issued. The error signal 14 sets the error state flag [2], and the control circuit 8 issues a hold signal 16 for holding all registers related to microprogram instruction processing. At the same time, the error microprogram word bt' is corrected by the error correction circuit 7 (microprogram word bt), and read out from the register 5 by the error signal 14.
, the microprogram word b is stored in the write data register 11.
1 is set in the error address register 10, and the address B1 of the error microprogram word by the output of the address register 9 is set in the error address register 10, respectively. Then, at the next timing (T6 step), the hold signal 16 is released, B3, which is the final step address of the B instruction, is stored in the address register 2, microprogram word b2 is stored in the read register 5, and the address register 9 is address B of microprogram word b2.
2 is set respectively. On the other hand, the error-corrected microprogram word b1 is decoded by the decoder 18 to control various registers. The EOP 13 signal of the B instruction is output from the microprogram word b2 at step T6, but at this time, since the aforementioned error state flag 12 is set, the control circuit 8 outputs the select signal 15. Note that the error status flag 12 is cleared by EOP 13 at step T8. Then, the next instruction (C instruction) is not activated, and the error address B held in the error address register 10 is
1 is set in the address register 2 by the select signal 15. At the next timing (T7 step), hold signal 1
8. The write instruction signal 17 is output from the control circuit 8, and while the registers related to the microprogram are held for several T (77 to T1), the error-corrected microprogram word held in the write data register 11 is bl is written to control memory 3. In other words, the write process is performed between the commands and the command break 1]. At the Ti step where writing ends, the select signal 15 is issued again, the hold signal 16 is released at the same time, and the T
At step I+1, start address C of the next instruction (C instruction)
O is set in address register 2. Thereafter, the C instruction performs the same processing as the A and B instructions. Note that the write process is treated as an interrupt process, but if there is another interrupt, other processes are given priority. Furthermore, if an error occurs in a microprogram word twice or more during instruction execution, the latest error-corrected IE microprogram word is to be written. Although the embodiment shown here only holds one error address and error correction microprogram word, by providing another register or buffer, it is possible to write the error microprogram word multiple times. It is clear that DETAILED DESCRIPTION OF THE INVENTION According to the present invention, when an error is detected during instruction execution, only the error correction is performed, and the writing process is performed after the instruction is completed and the end of the instruction. This has the effect of reducing the processing time of an instruction in a case where a correctable error occurs during instruction execution. In particular, in cases where errors occur multiple times at the same address, the overall processing time can be reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of a conventional technique, and FIG. 3 is a time chart showing the operation of the embodiment of the present invention. Explanation of symbols of main parts 29... Address register 3... Control memory 6... Error detection circuit 7... Error correction circuit 8... Control circuit 10...Error address register 11...Write address register

Claims (1)

[Claims] (1) A control memory for storing a microprogram, an error detection means for detecting an error in a microprogram word read from the control memory, an error correction means for correcting the error, and a control memory for detecting an error in a microprogram word in which an error has occurred. a first holding means for holding an address; a second holding means for holding a microprogram word after error correction;
and control means for controlling writing of the microprogram word in the second holding means into the control memory by the address of the first holding means in response to the end of a microprogram sequence in an instruction. Microprogram controller.