JPS63143589A - Frame interrupt controller - 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 the Invention The present invention relates to a frame interrupt control device for a display device in a computer system.

Conventional technology Frame interrupts generate interrupts to the CPU once during the scanning period of one screen of a rask-scan type CRT display device. Conventionally, the vertical synchronization signal supplied to the CRT display device was used as the interrupt source. . Therefore, the frame interrupt processing program is executed during the vertical blanking period, and the shape and position of the cursor are changed within this frame interrupt processing program.

If these processes are completed during the vertical blanking period, changes in the display contents will be completed while the screen is not being displayed, so there will be no unsightly conditions such as screen flickering.

Problems to be Solved by the Invention However, in the conventional configuration, if the process of changing the shape or position of the cursor is not completed within the vertical blanking period, the screen change related to the cursor overlaps with the display period, so the cursor and display contents are It had problems such as flickering.

In view of this, an object of the present invention is to provide a frame interrupt control device that does not cause such flickering problems.

Means for Solving the Problem In order to solve the above problem, the frame interrupt control device of the present invention specifies a line counter indicating the position of the horizontal scanning line and a specific number of horizontal scanning lines on the display screen. It includes a line number register and a comparator that generates an interrupt signal to the CPU when the contents of the line counter and the line number register match.

When the comparator detects that the value set in the active line number register is equal to the value of the line counter indicating the row position of the horizontal scanning line, an interrupt signal is output to the CPU. The time from when the interrupt signal is generated until the horizontal scanning line reaches the vertical blanking period is given as an interrupt processing time margin, and preprocessing that does not affect the screen can be performed during this period.

Embodiment FIG. 1 shows a configuration diagram of a frame interrupt control device in an embodiment of the present invention. In Figure 1, 1
is the CPU of the computer system, 2 is a display dot clock, 3 is a column counter that indicates the horizontal position of the display screen, and 4 is a row counter that counts the carry of column counter 3 and indicates the vertical position of the scanning line. , 5 is a line number register that stores a specific number of lines in the vertical direction of the display screen, 6 is a comparator that generates an interrupt signal to the CPU 1 if the contents of the line counter match the contents of the line number register 6, 7 is comparator 6
This is an interrupt signal output from the CPU 1 to the CPU 1. FIG. 2 is a diagram showing the relationship between the display screen, row counters, and column counters.

In FIG. 2, 1o is a display screen on a CRT display, and a row counter 4 and a column counter 3 are counted up as the scanning lines move in the directions of arrows 12 and 11, respectively. FIG. 3 is a timing diagram showing the operation of the comparator 6. Assuming that the value N is stored in the line number register 6, an interrupt signal 7 is output when the content of the line counter 4 reaches N.

As described above, if an interrupt can be generated to the CPU 1 in the middle of screen display as in this embodiment, there will be a time t between the interrupt 9 interrupt signal 7 and the vertical blanking period as shown in FIG. It makes a difference. When a process that must be performed during the vertical blanking period (for example, moving a cursor) is not completed within the vertical blanking period, the process within the vertical blanking period can be completed by performing a process that does not operate the screen within this time t. You can give yourself some leeway.

Further, as shown in FIG. 5, by changing the display contents using this interrupt signal 7, the display screen 10 can be divided into 13 screens 1 and 14 screens 2. usually,
Screen division, which requires complicated hardware, can be easily performed using an interrupt processing program.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, when a process that must be completed within a vertical blanking period (for example, moving a cursor) is not completed within the vertical blanking period, an interrupt signal is generated in advance; Processing in which the screen is not operated before the blanking period can be executed in advance, and a margin can be given to the processing within the vertical blanking period. Furthermore, the display screen can be easily divided, which has a great practical effect.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a relationship diagram between the display screen, row counter, and column counter, Fig. 3 is a timing diagram showing the operation of the comparator, and Fig. 4 is an interrupt signal and A relationship diagram of vertical blanking signals, FIG. 5 is an explanatory diagram of screen division. 3...Column counter, 4...Row counter, 6...Line number register, 6...Comparator, 7...Interrupt signal . Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4 Figure 5 Figure 11

Claims (1)

[Claims] a column counter that divides a display dot clock, a row counter that counts carries of the column counter, and a line number register that specifies the number of horizontal scanning lines on the display screen;
A frame interrupt control device comprising: a comparator that compares the contents of the row counter with the contents of the line number register and generates an interrupt signal to a CPU if they match.