JPS6250888A - Display system - 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 [Technical Field of the Invention] The present invention relates to a display system that has a plurality of access factors other than display and accesses fresh memory according to these factors to obtain a desired output.

[Technical background of the invention and its problems]

It is a well-known fact that the data memory (refresh memory) accessed by the display control LET (hereinafter referred to as CRTC) needs to be accessed from sources other than the CRTC in order to update and refer to data. Normally, access other than CRTC is ? Armware (CPU)
However, in a computer system with a built-in character generator (CG), access by a serial printer (SP) may also be considered since large-capacity ROM-JI such as Kanji fonts are commonly used.

As described above, when there are a plurality of accesses other than CRTC, conventionally, for example, firmware access and SP access are alternately performed, and the access permission times are set at a fixed ratio. Generally, the printing speed of serial printers varies depending on the model, so fixing the access ratio as described above is wasteful from the perspective of the efficiency of the entire system. .

[Purpose of the invention]

The present invention has been made in view of the above drawbacks.CR
To provide a display system that improves system configuration by dynamically switching access ratios to the factors when there are multiple factors other than TC that request access to data memory or photo memory. With the goal.

[Summary of the invention]

According to the present invention, the access ratio for each request of service time allocated for purposes other than display is switched dynamically using software or semi-fixedly using a DTP switch or the like.

For this reason, the above access ratio is set and stored by the CPU in a register (a DIP switch may be used, but in this case it is semi-fixed) and the horizontal synchronization signal is counted, and the valid bit position set in the above register or switch is stored. The system includes a gate circuit that outputs a significant signal when it detects that a value corresponding to the value has been reached, and a method is adopted in which access time is allocated to each access factor according to the logic state of the output of this circuit.

This makes it possible to dynamically change the access ratio for access factors other than display.
It is possible to improve overall performance. Furthermore, the same hardware can support various system configurations.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be described in detail using the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention.

In the figure, 11 is a 2-bit binary counter.
Horizontal synchronization signal (H8YNC) Counts g and transmits the output to the decoder 12. The output decoded by the decoder 12 is supplied to one input terminal of AND gates 1:I-16. The output of the register 17 is supplied to the other input terminals of the seventh node f-'F13 to F16. register 17
can be set to any value by software. The above AND gates 13 to 16 outputs are OR gate J
Supplied to &. OR f-to 1B output is AND gate 1
9 is supplied to one input terminal of the inverter 2.
0 is also supplied to one input terminal of the AND gate 21. H8YNC is supplied to the other input terminals of ANDf-)19°21. Andf-t19 output indicates the access permission time to the serial printer.
The -121 output serves to indicate the access permission time for the firmware.

FIG. 2 shows typical signals generated by the CRTC and their timing. In the figure, DISPTMG represents display time, and the HIGH level section corresponds to l raster displayed on the CRT (horizontal video section).
The -LOW'' level section indicates the horizontal retrace time, that is, the CRT non-display section (horizontal link).H8YNC indicates the horizontal synchronizing signal.In the embodiment of the present invention, this HBYNC It is assumed that services other than CRTC will be provided in this section.

FIG. 3 shows the service ratio and time for each service when there is a firmware access and a serial printer access as access request sources other than the CRTC. The shaded section indicates the section where the service was actually provided. In the example shown in Figure 3, the ratio of firmware access time and serial printer access time is set to 1.
This is an example when the ratio is set to 1.

FIG. 4 shows the ratio of firmware access time to serial printer access time when the ratio is 3 to 1, and the shaded areas indicate actual service.

FIG. 5 is a timing chart showing the operation of an embodiment of the present invention in which the ratio between firmware access time and serial printer access time can be dynamically changed.

Hereinafter, the operation of the embodiment of the present invention will be explained in detail.

Figure 3 shows the firmware access time and serial printer access time when the service ratio i is set to 1:1, assuming two cases: a case where the service request other than the CRTC is for firmware, and a case where a font is read by a serial printer. As mentioned above, the diagonal lines indicate that the service was actually performed. A-B in the figure shows the time allocated for the serial printer, but because the speed of the serial printer is slow, it is not actually serviced. This means that the system is wasted, and the timing chart shown in FIG. 4 is an improvement to this problem. That is, the ratio of firmware access time to serial printer access time is t-3.
By making the ratio 1 to 1, the actual frequency of serial printer services is the same as in FIG. 3, but since the number of services for firmware increases, the firmware processing speed increases. In general, the speed etc. of serial printers differ depending on the model, and furthermore, the operation of reading fonts to serial printers is not always active, so each request for service time allocated for purposes other than CRTC It can be understood that the more fixed the access ratio is, the less efficient it is.

As described above, the present invention provides a display system that can dynamically change the access ratio for each request for nine bis times allocated to a source other than the CRTC, either dynamically using software or semi-fixedly using a DTP switch or the like. The purpose is to provide The logic used for this purpose is shown in FIG.

In the figure, 11 is a 2-bit binary counter, which is sequentially counted up by the falling edge of H8YNC. The output of counter 11 is input to decoder 12.

The outputs of the decoder 12 are ANDed by the AND gates 13 to 16 of the signals corresponding to the outputs of the 4-bit register 17, and are outputted via the OR gate 18. The register 17 is used to allocate firmware access time and serial printer access time, and can be set to any value using software.

Now, when the value of '0001' is set in the register 17, the output of the OR gate 18 will be set to ``11'' of the register 17 at the cycle of H8YNC according to the count value of H8YNC as shown in Figure 5. A logic "11" is output only when the count value corresponding to the bit is reached. This output (OR gate 18) is ANDed with H8YNC (AND gate 21) and becomes the serial printer access permission time. On the other hand, OR gate 18 is logic'
The section ``Om'' will be used as the firmware access permission time.

From the above explanation, it is clear that by changing the value set in the register 17, the ratio between the serial printer access time and the firmware access time can be changed freely.

As described above, the gist of the present invention is to provide an entire system that can dynamically change the access ratio (service) for each request other than CRTC.

Incidentally, it is also possible to change the access ratio in a semi-fixed manner by providing a switch corresponding to each bit in the register 17, which was explained in the embodiment of the present invention. The above-mentioned means are just one method for realizing the present invention, and it is easily assumed that the present invention can be realized by various other means.

〔Effect of the invention〕

As explained above, according to the present invention, the system construction processing speed can be increased by dynamically switching the access ratio. Furthermore, it is possible to optimally construct multiple systems using the same hardware configuration.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Figs. 2 to 4 are diagrams cited to explain the operation of the embodiment of the present invention, and Fig. 5 is a timing diagram showing the operation of the embodiment of the present invention. It is a chart. 11...Counter, 12...Decoder, 13-16
・19・21...AND gate, 17...Register, 18...OR gate, 20...Inverter f-)
. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (1)

[Claims] In a display system that has multiple access factors other than display and accesses the display memory according to these factors to obtain a desired output, a register or a register in which access time assignments for the above access factors other than display are set and stored externally is used. Obtain a value obtained by counting the memory circuit of the switches, the value set and stored in the memory circuit, and the horizontal synchronization signal used for display, and this count value corresponds to the effective bit position set in the memory circuit. and gate means for outputting a significant signal only when the value is reached,
This is a patented display system that allocates access permission time to each factor according to the logic state of the gate output.