JPH04349493A - Display data test device - Google Patents

Abstract

PURPOSE:To input processed character data before it is inputted to a D/A converter and to send it out to a CPU as to the device which tests the processed data for a screen display. CONSTITUTION:At the timing of the processing of the character date to be tested, the character data before being inputted to the D/A converter 11 is inputted and stored in a display test FIFO 5, whose contents are sent out to the CPU 14 through a status register 6.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to raster scan type CR
The present invention relates to a test method for a display data generation device for a T display device, and particularly relates to a test for character display.

Screen displays on personal computers include text displays and graphic displays. Regarding the graphic display, the contents of the video RAM “
1" or "0" is reflected in the display as is. For text display, the contents of the text RAM are reflected as the code of the display character, and that code is the display character code of the character generator ROM (hereinafter referred to as CG-ROM). Therefore, what is displayed is the contents of the CG-ROM.

[0003] Furthermore, as for character fonts for display characters, 24-dot fonts, which are much more beautiful than 16-dot fonts, have become increasingly popular. A computer requires means for performing such screen display, and a display data generation device realizes this means. Therefore, an effective method for testing display data generation devices is desired.

0004

2. Description of the Related Art When displaying data on a CRT display device, the data to be displayed is converted by a display data generation device into a format that can be displayed on the CRT display device. Display methods include graphic display and text display. In graphic display, video RA consisting of n planes
The data converted by the display data generation device including M is sent to a digital-to-analog converter (hereinafter referred to as a D/A converter) as n-bit parallel data display data. Regarding text display, the data is sent from the text RAM to the D/A converter via the CG-ROM. At the same time, a DISP signal representing a display period is sent to the D/A converter. The D/A converter converts a digital signal representing display data into an analog signal and sends the analog signal to a CRT display device.

As is well known, when confirming the operation of a display data generating device, test data is prepared in advance and the test data is actually displayed on a CRT display device. Test data can be points, geometric figures, characters, or a combination of these. The tester visually follows the display contents on the screen and checks for any abnormalities. Therefore, the judgment as to whether there was any abnormality depended on the subjectivity of the examiner at the time.

[0006]

As described above, conventional display data generation devices have been tested by a tester actually viewing the screen of a CRT display device with his or her own eyes. The tester was required to constantly stare at the screen in front of the CRT display throughout the test. Therefore, testing work has become a very heavy burden for testers. especially,
When shipping personal computer products, for example, when a thousand computers must be tested in a single day, the burden placed on testers is immeasurable. In some cases, the tester's eye fatigue directly affected the test results.

[0007] As described above, conventional tests were conducted through the eyes of the tester and relied on the tester's subjective judgment at the time. Therefore, there was a problem that it was a spectator-like test and accurate test results could not be expected.

SUMMARY OF THE INVENTION In view of these conventional problems, it is an object of the present invention to provide a means for quickly obtaining objective and accurate test results.

[0009]

According to the invention, the above-mentioned objects are achieved by the means set out in the claims.

That is, in the present invention, when writing a character code of a displayed character to a text RAM in order to display the character on a CRT display device, the character font data representing the displayed character is written before being input to a D/A converter. This is a device for testing whether the target display character is correctly represented in the test, and includes a test code register that stores the character code of the display character related to the test in advance, and a latch for notifying the start and end of the test. When a character code equal to the contents of the test code register is written to the permission register and the text RAM, the D/
A comparison circuit that instructs to import the character font data before input to the A converter, and upon receiving instructions from the comparison circuit,
This display data testing device includes a display testing FIFO that takes in and stores character font data, and a status register that stores the character font data stored in the display testing FIFO that is sequentially taken out in a first-in, first-out manner.

[0011]

[Operation] FIG. 1 is a system configuration diagram relating to display data testing. When displaying data on the CRT display device 16, the display data is written into the video RAM or text RAM. When the display data is a character, it is written to the text RAM, and in writing to the text RAM, the character code is written to the code RAM 12, and the character color is written to the attribute RAM 13. Since the attribute RAM 13 in FIG. 1 has a capacity of 4 bits, any one color from among 16 preselected colors can be displayed on the screen. On the other hand, an address indicating the display position of the CRT display device 16 is outputted from the CRT control device 15 to the text RAM 8.

Since the character code does not represent even the size or font of the character, the character code written in the code RAM 12 is converted into character font data in order to determine the shape of the character to be displayed on the CRT display device 16. Ru. This conversion is performed by CG-RO in FIG.
This is done through M9. CG-ROM9 contains “Co
urier”, “Helvetica”, “Times”
Character sets are stored for each font such as ``Courier'' and font size such as 10 point and 12 point. Therefore, even if the font is the same as ``Courier'', there are multiple character sets with different font sizes. be.

The D/A converter 11 converts each display-related digital signal outputted from the timing adjustment circuit 10 into an analog signal and sends it to the CRT display device 16. Since the shading of each of the three primary colors of light can be continuously changed using analog signals, the CRT display device 16 can display virtually any color specified. Conventional systems that use digital signals to represent the three primary colors could only discretely change the shading of each color, so they could only display a limited number of colors.

The present invention is for testing whether each digital signal related to display before being input to a D/A converter is correctly converted and generated in a display system. In FIG. 1, the test device 1 takes in each digital signal before being input to the D/A converter 11, and stores it in the display test FIFO 5. The comparator circuit 4 compares the contents of the test code register 8 with the contents of the code RAM 12 to determine the timing of taking in the data.

The CPU 14 notifies the test apparatus 1 of the start and end of the display data test by writing predetermined data into the latch permission register 3. Further, the correctness of the display data is confirmed by the CPU 14 reading out the display data that has been stored in the display test FIFO 5 and transferred to the status register 6 in a first-in, first-out manner. The CPU 14 reads the read data at this time and
The correctness of the displayed data is confirmed by comparing it with the expected value prepared in advance. Note that the DISP signal indicates the display period.

[0016]

Embodiment FIG. 2 is a diagram showing an example of input/output information between a CPU and a test device. The test code register 17 shown in FIG. 2A is a register to which the CPU writes, and stores a character code used as a trigger. Figure 2(b)
The latch permission register 18 shown in FIG. 1 is also a register written by the CPU, and its most significant digit is written with "1" at the start of the test and "0" at the end of the test. The status register 19 shown in FIG. 2(c) is
This register is read by the PU, and stores graphic data, character font data, and character color data before being input to the D/A converter, as well as a bit indicating whether a test is being performed or not, and whether the stored data is valid or not. It has a bit indicating invalidity.

FIG. 3 is a diagram showing an example of the circuit configuration of the test device. In FIG. 3, a test code register 21 stores a character code serving as a trigger, and a comparator 25 compares this code with the character code written in the code RAM. The AND circuit 28 is
The output of the comparator 25, the output of the NOT circuit 26 which conveys the DISP signal information indicating the display period, and the NOR circuit 27 which conveys the start and end of the test notified to the latch permission register.
and the output of . This result is true because the character font data of the characters related to the test is
This is the time when the data is displayed before input, and the output of the AND circuit 28 serves as the output of the comparison circuit 22 to instruct the capture of display data.

[0018] The display data is captured using the test FIFO.
will do it. Here, the display data displayed on the CRT display device 30 is latched before being input to the D/A converter 29. In this embodiment, in addition to character font data, graphic data and character color data are also imported, making it possible to test these data. FIFO for display testing
The display data accumulated in the test device 23 is transferred to the status register 24 on a first-in first-out basis, and the contents are transferred to the status register 24 on a first-in, first-out basis.
0 to the CPU.

FIG. 4 is a flowchart of the test method. S1 to S7 indicate the process number of each process, and below,
This process number is written in parentheses after the description of the corresponding process. When testing the display system for characters using the testing device according to the present invention, first, "A to Z" are displayed on the screen of the CRT display device (S'1). Next, write “80H” to the latch permission register to notify the start of the test, and write the uppercase letter “A” to the test code register.
Write the character code “41H” representing
2) Test the English capital letter "A". Next, the contents of the status register are read (S'3), and it is checked whether character font data representing the uppercase English letter "A" has been stored (S'4). If the data has been stored, the read data from the status register is stored in the CPU memory 32.
This is later compared with a previously prepared expected value. This concludes the study of the capital letter "A".

[0020] Then, check whether the test should be continued (S6
), in the case of continuation, “80” is written to the latch permission register again.
Write "H" and write the uppercase "H" to the test code register.
Write the character code “42H” representing “B” (
S'7), carry out the test in the same manner as in the case of "A". The process is repeated in the same manner up to Z, and finally it is determined whether each read data from the status register stored in the memory of the CPU matches a previously prepared expected value.

FIG. 5 is a diagram showing the display screen during the test. In FIG. 5, a display test is being conducted for the English capital letter "A", and the character "A" is displayed on the display screen 31. The display screen 31 in FIG. 5 is divided for explanation, and the letter "A" indicates both rows and columns.
It is displayed in the 1st square. What is taken into the display test FIFO is the part in the grid of row #1 and column #1, which is the part indicated by the thin line where the display and code match. Regarding the display data of this part, it is possible to test graphic data and character color data as well as character font data. For example, if each square in Figure 5 is 14 dots horizontally and 24 dots vertically, 14 x 24 character font data will be stored in the display test FIFO for display data for one square, and graphic data will be stored simultaneously in the display test FIFO. If you also import text color data, it is possible to test graphics and text color at the same time as text.

[0022]

[Effects of the Invention] As explained above, according to the present invention,
Character display system tests can be quickly performed with a very simple circuit configuration. Moreover, the test according to the present invention
It does not involve any subjective judgment by the tester, making it extremely reliable. Furthermore, since it is not a visual test, it reduces the strain on the examiner's eyes, and
In particular, there is an advantage that character display tests can be carried out at high speed.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram related to a display data test.

FIG. 2 is a diagram showing an example of input/output information between a CPU and a test device.

FIG. 3 is a diagram showing an example of a circuit configuration of a test device.

FIG. 4 is a flow chart of the test method.

FIG. 5 is a diagram showing a display screen during a test.

[Explanation of symbols]

1, 20 Test equipment 2, 17, 21 Test code register 3, 18
Latch permission register 4, 22 Comparison circuit 5, 23 Display test FIFO 6, 19, 24 Status register 7
Video RAM 8 Text RAM 9 CG-ROM 10 Timing adjustment circuit 11, 29 D/A converter 12 Code RAM 13 Attribute RAM 14 CPU 15 CRT control device 16, 30 CRT display device 25 Comparator 26 NOT circuit 27 NOR circuit 28 AND Circuit 31 Display screen 32 Memory

Claims (1)

[Claims] Claim 1: When writing the character code of a display character to a text RAM in order to display the character on a CRT display device, the character font data representing the display character is correctly designed for the intended purpose before being input to a D/A converter. This is a device for testing whether display characters are represented, and includes a test code register (2) in which the character code of the display character related to the test is stored in advance, and a text RAM (8).
), when a character code equal to the content of the test code register (2) is written to the D/A converter (11), a comparison circuit (4) instructs the D/A converter (11) to take in the character font data before input; , a display test FIFO (5) that receives and stores character font data in response to instructions from the comparison circuit (4), and a display test FIFO (5) that stores character font data in a first-in, first-out manner. A display data testing device characterized by comprising a status register (6) for storing sequentially retrieved data.