JPS60229092A - Display control circuit operation inspection device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an operation inspection device for a display control circuit of a computer system.

(Conventional configuration and its problems) In recent years, the production of computers has increased year by year, and along with this, there has been a demand for improved efficiency in testing product operation.

A conventional method for testing the operation of a display control circuit will be described below with reference to the drawings.

FIG. 1 shows an outline of the configuration of a general display control device. In FIG. 1, 101 is an oscillator, 102 is a dot counter, 103 is a display controller, 1
04 is a multiplexer, 105 is a blink counter that counts the blink signal that controls the blinking time of the display screen, 106 is a video memory, 107 is a display control circuit, 108
109 is a central processing unit, and 110 is a display device.

Conventionally, when testing the operation of a display control device configured as described above, the display control device was actually connected to the central processing unit and the display device, and in this state, the original operation of the display control device was tested using a test program. A method has been adopted in which a test is performed and an operation test is performed. With this method, the central processing unit can check the operation of the display controller and video memory connected to the system path using a test program, so the inspection speed is at the calculation speed level of the central processing unit, but the display control circuit In this case, the operation is confirmed by a human being visually observing the results output on a display device, which has the disadvantage that it is very time consuming and inefficient, and the reliability of the test is also reduced. This drawback becomes more noticeable as the functions of the display control device become more complex. For example, within a limited time, the display position of characters, the photos that make up the characters, ruled lines, underlines, link display, etc.
It is necessary to determine whether normal operations such as inverted display, high-intensity display, color display, scroll display, etc. are working, and to check whether there is any blurring or noise on the display screen.

(Object of the Invention) In view of the above drawbacks, the present invention provides an operation testing device for a display control circuit, which tests the operation of a display control circuit of a computer system without relying on human visual inspection.

(Structure of the Invention) To achieve this object, the display control circuit operation testing device of the present invention includes a dot counter, a display controller, a multiplexer, a link counter, and a video memory similar to those of the display control device to be tested. , a display control device for inspection having a display control circuit, a character clock comparator for synchronizing the character clocks of both the display control device to be inspected and the display control device for inspection, and synchronization of the image straightness synchronization signals of both. It consists of a vertical synchronization signal comparator that synchronizes both the blink signals, a blink signal comparator that synchronizes both the blink signals, and a video signal comparator that compares both video signals. The comparator and the blink signal comparator synchronize the display control device to be inspected and the display control device for inspection so that the operating states of both are exactly the same.

In this state, the test program causes both to perform the original operation of the display control device, the video signals of both are compared by the video signal comparator, and the central processing unit determines whether the results are the same. The operation of the display control circuit of the display control device to be inspected can be inspected without relying on visual inspection.

(Explanation of Examples) FIG. 2 shows an embodiment of the invention.

In FIG. 2, lOl is an oscillator, 102 is a dot counter, 103 is a display controller, 104 is a multiplexer, 105 is a link counter, 106 is a video memory, lO7 is a display control circuit, 108 is a system path, and 109 is a central processing unit. The above configuration is the same as the configuration shown in FIG.

201 is a dot counter A, 202 is a display controller A, 203 is a multiplexer Al2O4 is a link counter A, 205 is a video memo') A, 206 is a display control circuit A, 207 is a character clock comparator, 2
08 is a vertical synchronization signal comparator, 209 is a blink signal comparator, 21O is a video signal comparator, 211 is globe a,
212 is glove b, 213 is glove c, and 214 is glove d. In the figure, a portion surrounded by a broken line indicates a display control device to be inspected.

The operation of the display control circuit operation inspection apparatus configured as described above will be described below.

First, the display control device to be inspected and the operation testing device for the display control circuit are connected to the central processing unit 109 via the entire system bus. In this state, the dot clock 215 extracted by the globe A211 is input to the dot counter A201 via the character clock comparator 207. Next, glove b
The character clock 216 extracted in step 212 and the character clock A220 are transferred to the character clock comparator 207.
If they are different, dot counter A201
The input of the dot clock 215 is started.

As a result, the dot counter A201 stops counting, and its output, the character clock A220, maintains either a high level or a low level. At this time, the dot counter 102 is still counting. Then, when the character clock 216 changes and matches the character clock A220, the character clock 7 comparator 207 outputs the dot counter A201K.
.

The dot clock 215'f: is input again to operate the dot clock/return A201.

As described above, the operation of the dot counter A201 is stopped,
By repeating the start, the dot counter A201 operates in synchronization with the dot counter 102 after a certain point.

In the same manner as above, the vertical synchronizing signal comparator 2'08 synchronizes the vertical synchronizing signal 217 and the vertical synchronizing signal A221, and the plink signal comparator 209 synchronizes the vertical synchronizing signal 217 and the vertical synchronizing signal A221. The link signal 218 and link signal A222 are synchronized.

As described above, after the display control device to be inspected and the display control device for inspection are synchronized through the three-step synchronization, the display control device to be inspected and the display control device for inspection are made to perform the original operation of the display control device using the test glodarum. , video signal 219
The video signal A 223 is sampled by the dot clock 215 and compared by the video signal comparator 210, and the result is judged by the central processing unit 109.

The central processing unit 109 then operates a video signal comparator 210.
When the character clock, vertical synchronization signal, or pre/reverse signal becomes out of synchronization while determining the output of Generates an interrupt signal to the central processing unit 109, and prohibits the central processing unit 109 from determining an erroneous output of the video signal comparator 210 until the display control device to be inspected and the display control device for inspection are synchronized. .

By the above method, the operation of the display control circuit 107 of the display control device to be inspected can be accurately and quickly inspected without relying on human visual observation.

Figure 3 shows the character comparator 2 in Figure 2.
07, a vertical synchronizing signal comparator 208, and a plink signal comparator 209.

In FIG. 3, 301 is a clock generator, 302 is a counter B, 303 is a counter As, 305 is an interrupt signal generator, and the portion surrounded by a broken line is a comparator.

Here, counter B502 and counter A303 are 1/
The case of a 6 frequency divider will be explained.

FIG. 4 is a timing chart.

Now, at time to in FIG. 4, the frequency-divided signal B509 that is the output of the counter B502 and the frequency-divided signal A310 that is the output of the counter A303 are different.
The output of the selector 306 becomes high level, and the output of the selector 306, that is, the clock A311 of the counter A303, maintains the previous state, so the counter A303 stops and the divided signal A
310 remains unchanged.

Next, time 1. When the frequency division signal B509 changes and matches the division signal A310, the output of the XOR gate 304 becomes low level, the output of the selector 306 is switched, and the clock A311 becomes the same as the clock B508.

However, at time t2, the frequency division signal A310 changes, so the frequency division signal B509 and the frequency division signal A310 are different again, the clock A311 maintains its previous state, and the counter A303 stops.

Next, at time t3, the frequency-divided signal B509 and the frequency-divided signal A3
10 matches, clock A311 is clock B508
The counter B502 and the counter A303 are synchronized after time t4.

In the above operation, when the output of the XOR gate 304 is at high level, that is, the frequency divided signal A310 and the frequency divided signal B5
09 do not match, the interrupt signal generator 305 sends an interrupt signal to the central processing unit, informing the central processing unit that counter A 303 and counter B 502 are not synchronized.

FIG. 5 is a specific embodiment for explaining the operation of video signal comparator 210 in FIG.

In FIG. 5, 501 is a dot clock generator;
2 is display control circuit A, 503 is display control circuit B, 504
is flip-flop A, 505 is flip-flop B,
507 is a shift register, and 5]0 is an interrupt signal generator.

The operation will be explained below.

Now, consider a case where the display control circuit A302 and the display control circuit B503 are synchronized.

The output of the display control circuit A302 is converted to Fritsunoflow.

The output of the display control circuit B503 is connected to the fA504 and the output of the display control circuit B505 is connected to the dot clock 509, and the latched data is XORed.
Gate at gate 506.

If the outputs of the display control circuit A 302 and display control circuit B 503 match, the output of the ) 506 is stored in the shift register 507, and when the output of the 510 sends an interrupt signal to the central processing unit, and when the central processing unit detects this interrupt signal, it transfers the contents of the shift register 507 to the system path 508.
Read through.

By using the above method, the central processing unit can compare and determine the operations of the display control circuit A302 and the display control circuit B503 on a dot-by-dot basis.

(Effects of the Invention) As described above, the present invention provides an inspection display control having a dot counter, a disk gray controller, a multiplexer, a link counter, a video memory, and a display control circuit similar to the display control device to be inspected. a character clock comparator for synchronizing character clocks of the display control device to be inspected and the display control device for inspection, and synchronization of vertical synchronization signals of the display control device to be inspected and the display control device for inspection; a vertical synchronization signal comparator that synchronizes the blink signals of the display control device to be inspected and the display control device for inspection; and a video signal of the display control device to be inspected and the display control device for inspection. By providing a video signal comparator for comparing signals, the operation of the display control circuit of the display control device to be inspected can be inspected without relying on visual inspection, and inspection can be performed while scrolling, allowing dot-by-dot inspection. Therefore, it is possible to accurately inspect errors caused by noise in the video memory without missing them, and this has great practical effects.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a general display control device, Fig. 2 is a block diagram of an embodiment of the present invention, and Fig. 3 is a character clock comparator, vertical synchronization signal comparator, and blink signal comparator in Fig. 2. 4 is a timing chart for explaining the operation of the comparator in FIG. 3, and FIG. 5 is a diagram for explaining the operation of the video signal comparator in FIG. 2. be. 201...Dot counter A, 202...Display controller A, 203...Multiplexer Al2
O4... Blink counter A1205... Video memo IJA, 206... Display control circuit A, 207... Character clock comparator, 208... Vertical synchronization signal comparator, 209... Blink signal comparator , 2nd grade O...
Video signal comparator.

Claims (1)

[Claims] A character clock that is a basic clock of the display controller, a vertical synchronization signal that synchronizes the display device with the output of the display controller, and the display that is created by dividing the frequency of the vertical synchronization signal. An inspection display control device having the same functions as the display control device to be inspected, which has a function of generating a blink signal for controlling the blinking time of the display screen of the device and a video signal output from the display control circuit to the display device; a character clock comparator that synchronizes the character clocks of the display control device to be inspected and the display control device for inspection; and a vertical synchronization signal that synchronizes the vertical synchronization signals of the display control device to be inspected and the display control device for inspection. a comparator; a blink signal comparator that synchronizes the blink signals of the display control device to be inspected and the display control device for inspection; and a video signal that compares the video signals of the display control device to be inspected and the display control device for inspection. An operation testing device for a display control circuit, comprising: a signal comparator, and tests the operation of the display control circuit of the display control device to be tested based on the comparison result of the video signal comparator.