JPS6127000A - Inspection method of ram - Google Patents

Abstract

PURPOSE:To decide a RAM to be functioning normally when an address to be confirmed is sequentially added by one and when it exceeds an address of a RAM3 by writing/reading data in accordance with each address of the RAM and simultaneously detecting whether or not data of other addresses are destructed. CONSTITUTION:When the indication is given for inspecting a start of write/read of a RAM3, a micro processor 1 reads a program out of a ROM2 to start checking the RAM3. First of all, a specific data, for instance, a hexadecimal 55H is written in all the addresses of the RAM3. After that, an address to be confirmed is specified for trial reading of the data. When the read-out data is not 55H, the RAM3 is decided to be abnormal. Whereas the read-out data is 55H, another specific data, for instance, a hexadeciman AAH is written in the same address. The data is read by specifying the address to which the AAH is written. When the read-out data is AAH, all the addresses are sequentially specified for data reading. When the entire read-out data is 55H as it is, an address is added by one, and if is exceeds the address of the RAM3, the RAM is decided to be normal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for writing data to/outputting data to/from a RAM, and particularly relates to a method for inspecting a RAM.

Recent office automation (OA) IA devices have built-in microprocessors and have come to store and process data in RAM. In order to reduce costs, many of these OA devices do not have a means for recreational use in the RAM and write/continue output circuits.

However, as the commercial performance of OA equipment increases, the amount of data to be processed increases, and the R and AM capacities also increase. Therefore, the reliability of RAM functions has become more important. Therefore, in many of these devices, the RAM function is checked when the power is turned on or when an operator diagnoses the device.

When checking the RAM function, it is necessary to be able to easily perform a reliable function check including the write/continuation circuit.

[Conventional technology]

The method for RAM function is to first write data (55H) to a certain address, read it to check whether it has actually been written, and then write data [ΔA H) to the same address. Write and read and confirm. This operation is generally performed for all address spaces.

That is, by writing and reading 01 (11(l), and then writing and reading 101010 to the same address,
55i of RAM depending on whether there is an error in the data or not.
Perform the detection.

[Problem that the invention seeks to solve]

If you check the RAM function using the above method, for example, the check result may be good even though the RAM decoding circuit has failed and the address signal is not output correctly and no data is written to the specified address. It may happen.

In other words, if the least significant bit of the address signal is always 1'', data will be written to address (xxxl) regardless of whether address (xxxO) or address (xxxl) is specified.However, with the above method, Because the address is not checked, there is a problem that a failure is not detected and becomes a failure.' [Measures to solve the problem] The above problem is caused by the failure when writing and reading data to and from RAM. In a device that performs the following steps, the first step is to write specific data A to this address in the total RAM, read out the data by specifying an arbitrary address, and check whether the data is the specific data A or not. Second process and specific data A
is confirmed, specifying the address and writing specific data B different from the data 8, then specifying the address and reading the data, and confirming whether the data is the specific data B or not. When the L culm of No. 3 and the specific data B are confirmed, all the addresses except the above address are sequentially designated and the data is read out.The fourth step is to check whether the data is the specific data A. The problem is solved by the RAM inspection method according to the present invention, which includes steps and performs the second to fourth steps for all addresses of the RAM.

[Effect]

That is, data is written/read for each address of the RAM, and it is detected whether data at other addresses has been destroyed.

〔Example〕

FIG. 1 is a circuit block diagram showing an example of a printer circuit according to an embodiment of the present invention, and FIG. 2 is a flowchart explaining the operation of FIG. 1.

The microprocessor 1 reads a program stored in the ROM 2 and operates. Print data etc. are input from the interface control circuit 4. The microprocessor 1 temporarily writes the print data into the RAM 3.

The print data written in the RAM 3 is read out by the microprocessor 1, and if it is a character code, it is read out by the character generation circuit 7.
The corresponding character pattern is read out from the printhead control circuit IO and sent to the print head control circuit IO. The character pattern sent to the print head control circuit 10 is printed by the print head 11.

At this time, the microprocessor 1 simultaneously controls the space control circuit 8 to drive the space motor 9 to cause the carriage carrying the print head 11 to perform a space motion.

If the print data read from RAM 3 by the microprocessor IJv has a line feed specification, the line feed system fal1 circuit 5
is controlled to drive the line feed motor 6 to feed the paper.

When the microprocessor 1 receives a command from the operator panel 13 via the input port 12 to start checking the writing/reading of the RAM 3 as shown in FIG. 2, the microprocessor 1 reads the program from the ROM 2 and starts checking the RAM 3. do.

First, specific data, such as hexadecimal (55H), is written to all addresses in the RAM 3. After that, specify the address to be checked and try outputting that data one after another.

If it is not the data read here (55H), it is RAM3.
However, if the read data is [55H], other specific data, such as hexadecimal [
AAH].

Specify the address where [ΔΔH] was written above and read the data. The data read here is [A△1]]
If the deviation is determined to be an abnormality in the RAM 3, or if the read data is [ΔAH], all addresses are sequentially designated and the data is read.

If any of the data is not (55H), it is determined that the RAM 3 is abnormal, but if all the read data remains (55H), the address to be checked is incremented by 1.

Increase the address to be checked by +1 one by one, and if it does not exceed the address of RAM 3, repeat the above operation, and RA
If the address of M3 is exceeded, it is determined that RAM3 is always positive and the process ends.

〔Effect of the invention〕

As explained above, the present invention includes a write/sequence circuit and all)? AM function can be easily checked.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a circuit showing one embodiment of the present invention. FIG. 2 is a flowchart explaining the operation of FIG. 1. 1 is a microprocessor, 2 is a ROM, and 3 is a RAM. 4 is an ink face control circuit, 5 is a line feed control circuit, 6 is a line feed motor, 7 is a character generation circuit, 8 is a space control circuit, 9 is a space motor,
10 is a printing gutter control circuit; 11 is a print head; 1
2 is an input port, and 13 is an operator panel.

Claims (1)

[Claims] In a device that writes and reads data to and from a RAM, the first step is to write specific data A to all addresses in the RAM, and the first step is to read data by specifying an arbitrary address, and the data is read from the specified address. a second step of confirming whether or not data A is specified; and when specific data A is confirmed, specifying the address and writing specific data B different from the data A, and then specifying the address. a third step of reading data and confirming whether the data is the specific data B, and when the specific data B is confirmed, sequentially specifying all addresses except the address and reading the data; That data is the specific data A
A method for inspecting a RAM, characterized in that the second step to the fourth step are performed for all addresses of the RAM.