JP2773232B2 - CAD equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention is a CA that can efficiently perform pattern correction.
It relates to the D device.

<Prior Art> CAD apparatuses capable of designing wiring patterns with the aid of computers have become widespread. After once designing a pattern of a printed board using a CAD device, for example,
When a circuit mounted on a printed circuit board is modified, the printed circuit board pattern must be modified by the CAD device accordingly.

The operation of pattern correction in a conventional CAD device will be described with reference to FIG. Figure (1) shows the net NE before correction.
FIG. 9 is a diagram showing a wiring line based on the contents of T001. The contents of the net NET001 corresponding to the pattern in Fig. (1) are NE
T001: R1-2, C1-1, D1-1. This is the resistance of R1
This means that the pin No. 1, the pin No. 1 of the capacitor C1, and the pin No. 1 of the diode D1 are connected by the same wiring line. As a result, the CAD device is driven by the lines L1, L2, L shown in FIG.
Write 3 on the disk provided as a wiring line.

Here, it is assumed that a design change has occurred and a change has been made to disconnect the first pin of the diode D1 from the resistor R1 and the capacitor C1.
That is, the new net described in the CAD device is NET001 ':
R1-2 and C1-1. That is, in FIG. 16 (1), only the correction for deleting the lines L2 and L3 may be performed.

<Problems to be solved by the invention> However, in the conventional CAD device, the contents of the old net NET001: R1-2, C1-1, D1-1 and the new net NET001 ': R1-2, C1-1 are different. Interpret as another net, old net NET0
All the lines L1, L2, L3 constituting 01 are once deleted as shown in FIG. 16 (3) and re-wired from the beginning as shown in FIG. 16 (2).

However, such an operation requires re-wiring from the beginning where only a part of the net needs to be corrected, so that it takes a long time for the correction and the efficiency is low. Also, if a line that does not require correction (for example, L1) is deleted once and then re-wired, the route may be different from the previous route, so the printed board data and its products There is a possibility that documents and the like that have already been made cannot be used.

SUMMARY OF THE INVENTION An object of the present invention is to provide a CAD apparatus capable of deleting only a line that really needs to be corrected when a netlist is corrected (correction of a wiring pattern).

<Means for Solving the Problems> The present invention is to solve the above problems. A first invention is to provide a coordinate value of a component pin and a line segment constituting a wiring line connecting the specified component pin and the component pin. (55) in which the start point coordinates and end point coordinates are written, and a set of component pins (hereinafter referred to as a net) to be connected by the same wiring line in order to change the contents of the figure data storage section And a first storage unit (54) in which the component pins of each net are written, and a set of component pins connected by the same wiring line is calculated based on the contents of the graphic data storage unit. Means (41) for assigning a new net name to this, and writing the net name and the component pins of this net to the second storage unit (56); a first storage unit and a second storage unit for each component pin; Compare the net name of the storage unit and each of the second storage unit A list creating means (42) for creating, on the storage device (5), a list (57) in which the component pins are arranged in groups for each unit name; Means (43) for searching for a wiring line connected to a component pin to which a net name is assigned, and deleting a wiring line from this component pin to the first branch point or to another component pin from the graphic data storage unit (43) ) And means comprising:

According to a second aspect of the present invention, the net name of the first storage unit is divided into a plurality of groups in each group, and each group is composed of two or more component pins, instead of the deleting means (43). In the case, a means (44) for deleting a wiring line (L3) connecting different nets described in the first storage unit from the graphic data storage unit is provided.

<Operation> The wiring deletion function 43 deletes a wiring line from a component pin which is unused or used for another net due to a design change.

When the old net is divided into two or more nets due to a design change, the wiring deletion function 44 deletes a wiring pattern connecting the two nets to be divided.

<Example> Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a CAD device according to the present invention,
2 and 3 are diagrams showing the relationship between nets (lists) and component pins, FIGS. 4 and 5 are diagrams showing the relationship between graphic data lists and graphics, and FIG. 6 is a calculated net list. Figure,
FIG. 7 is a diagram showing a changed net list, FIGS. 8 and 10 are diagrams showing a comparison list, FIG. 9 is a diagram showing a changed wiring pattern, and FIGS. 11 and 12 are diagrams of the first invention. FIGS. 13 to 15 are diagrams for explaining the operation, and FIGS. 13 to 15 are diagrams for explaining the operation of the second invention.

The device shown in Fig. 1 has the function of making a pattern wiring master for manufacturing a printed circuit board, and the function of redrawing it into a formal circuit drawing that traces a circuit diagram drawn by a designer based on a freehand drawing. However, in the present specification, a description will be mainly given of a function of creating a printed board as an example. The route of the wiring line can be automatically searched by a computer, and the wiring route can be manually input.

In FIG. 1, reference numeral 1 denotes a keyboard for inputting various wiring data of electronic components to be wired to the computer 4 by characters, numerical values, and the like. In a concrete example,
The information includes connection information between component pins (net list information), component names of electronic components (for example, IC names), and the like.

Reference numeral 2 denotes a magnetic tape (hereinafter simply referred to as MT), which can be used to input information instead of outputting it to the computer 4 using the keyboard 1.

A tablet 3 controls a cursor position displayed on the screen of the CRT 7. The tablet 3 is used to input, for example, the coordinates of the start point and the end point of the wiring line to the computer 4 and the position of the electronic component to be wired on the printed board.

Reference numeral 4 denotes a computer for controlling the entire operation of the CAD apparatus. In particular, the computer 4 has functions 41, 42, 43, and 44 for performing operations characteristic of the present invention (this will be described later). Features that feature this
41, 42, 43, and 44 can be realized by executing a program included in the computer 4.

Reference numeral 5 denotes a disk, a keyboard 1, an MT2, and a tablet 3.
The data input through the computer and the data calculated by the computer 4 are stored. That is, data such as the component list 51, the component pin position list 52, the original net list 53, the changed net list 54, the graphic data list 55, the calculated net list 56, and the comparison list 57 are stored under the control of the computer 4. Also, if the computer 4 is a CA
Various programs for operating as a D device are also stored.

Reference numeral 6 denotes a wiring pattern display processing unit which has a function of reading the contents of the graphic data list 55 and displaying the read contents on the CRT 7. Since the wiring pattern display processing unit 6 is a known one and is not a main part of the present invention, the description of the configuration and operation of this part is omitted.

In FIG. 1, the illustration of a plotter for creating a photo original of a printed circuit board wiring (or a photo original of a circuit drawing) based on the graphic data list 55 is omitted.

The operation of the FIG. 1 apparatus configured as described above will be described.

(A) Operation before Correction of Wiring The operation of this item (A) and the configuration for performing this operation are not essential parts of the present invention, but will be briefly described to make the invention easier to understand. The operator uses the keyboard 1, for example, to input a symbol representing the type of component of the electronic component mounted on the printed board to the computer 4. For example, IC
If 1 is the component number XXX, it is stored in the component list 51 of the disk 5 in a relationship as shown in the figure by the function of the computer 4 not shown. The data of the number of component pins and the component pin interval of the electronic component having the component number XXX are stored in an area (not shown) of the disk 5 in advance, and can be used to create a printed board by sequentially referring to the data.

Next, the operator instructs the computer 4 using the tablet 3, for example, on the position of the electronic component to be arranged on the printed board (or on the circuit diagram). That is, by operating the tablet 3, the cursor is arranged at a desired position on the screen of the CRT 7. The computer 4 can recognize the cursor coordinates using a cursor coordinate value reading function (not shown). Then, the electronic component specified by the keyboard is arranged at the position designated by the cursor, and the coordinate values (for example, X1, Y1) of each component pin of the electronic component are stored in the component pin position list 52 and the graphic data list 55 of the disk 5. Can be stored. At this time, the component list 51 described above is used. The components may be arranged automatically by the computer 4 instead of manually by the operator.

Next, the operator inputs the net information (connection data) to the computer 4 with the keyboard 1 while looking at the design circuit diagram, for example. The net is a group of component pins to be connected by the same wiring line as described above, and will be described with reference to FIGS. 2 and 3. FIG. 3 is a view showing electronic components IC1, IC2, and IC3 mounted on a printed board and connection lines of respective terminals. If it is desired to perform wiring as shown in FIG. 3, if the net names of the wiring lines are A0001 and A0002, the operator will obtain A0001: IC1-8, IC2-4, IC2-5, IC3-6 A0002: IC1-3, IC3-2 and IC3-8 are input to the computer 4. As described above, when the operator collectively inputs the component pins to be connected by the same wiring line to the computer 4 in advance, the computer 4 transmits the net data to the second
Original list 53 of disk 5
To store. Note that, in many cases, the computer does not instruct the net names sequentially, but rather the computer assigns the net names (for example, A0001, A0002,...) In a series in the order in which they are input.

When the position information of the component pins is input as described above, the wiring pattern display processing unit 6 displays the outline indicating the area where wiring can be performed and the component pins of the electronic component arranged first on the CRT 7. Then, in the CAD device for performing the wiring work manually, the operator moves the cursor to a desired position on the CRT 7 and inputs the start point coordinates and the end point coordinates of the wiring line to the computer 4 one after another. The computer 4 can know the coordinate values of the starting point and the ending point by a known cursor coordinate reading function, so that the designated wiring line can be easily recognized.

The graphic data and the graphic displayed on the CRT 7 (which is also a pattern diagram of a printed board) will be described with reference to FIGS. The component pins P1, P2, P3 are located at the positions shown in FIG.
Assume that these are to be connected by a wiring pattern as shown in FIG. The operator places a cursor at the coordinates (X1, Y1) and instructs the computer 4 that this is the starting point. Next, the cursor is placed at the coordinates (X2, Y1) and the computer 4 is instructed that this is the end point. When the line segment is followed, the computer attaches the symbol L1 and plots the coordinate values of the start point and the end point in a graphic form. Write to data list 55. Furthermore, this line segment L1
The number indicating the level of the printed circuit board on which the symbol is placed, the "color" displayed on the CRT 7, and the data indicating the width of the line segment are also stored.

In this way, the cursor is sequentially moved to desired positions, and when the wiring lines L2, L3, L4, L5 shown in FIG. 4 are input, the coordinates of the start point and the end point are stored in the graphic data list 55.

The wiring pattern display processing unit 6 sends the figure data list 55
Are sequentially read and displayed on the CRT7.
Therefore, as soon as a line segment is input to the computer 4 with the tablet 3, the line segment is displayed on the CRT 7, and the user can proceed with the wiring work while viewing the line segment.

The above-described level, color, and line width data will be described. In a CAD device, a printed board is captured on a plurality of surfaces, and these surfaces are called levels. For example, it is set in advance in the design stage that the component side of the printed board is level 1, the solder side is level 2, and the silk printed figure is level 3. Then, the operator instructs the computer 4 on which level the wiring line (graphic information) to be stored is to be stored by pressing a specific key of the keypad 1. Therefore, the computer 4 can store the level number in the graphic data list 55 together with the line segment (for example, L1) as shown in FIG. In addition, which level of wiring pattern is displayed in which color can be set in advance, so that color data can be simultaneously written into the graphic data list 55 if a level number is designated from the keyboard. Line width data can be input from the keyboard 1 in the same manner.

The operation of manually inputting the wiring line has been described above. However, in the CAD apparatus in which the computer 4 automatically searches for the wiring path, the start point and end point coordinate values of the line segment in the data of FIG. 5 are automatically stored. .

As described above, the wiring pattern figure of the printed circuit board based on the original net list 53 is formed in the figure data list 55.

(B) Wiring Correction Operation The configuration for performing the operation of this item (B) is a main part of the present invention. The case where it is desired to correct the printed wiring once designed includes, for example, a case where a base design circuit is changed, a case where an input of the original net list is made, and the like. Hereinafter, the third
The case where the connection in the figure is modified as shown in FIG. 9 will be described as an example.

The changed net data for connection as shown in FIG. 9 is input to the computer 4 from the keyboard 1 or MT2. Since the computer 4 uniquely assigns a net name in the order of input, a net name different from the original net is assigned even to a net which is not changed from the connection shown in FIG. Thus, the computer 4 creates the changed netlist 54 on the disk 5 (see FIG. 1). FIG. 7 shows a modified netlist having contents according to the connections shown in FIG. That is, the two nets (A0001, A0002) in FIG. 3 are changed to four nets (B0001 to B0004) in FIG.

With such a change, the operation of correcting the wiring pattern is performed as follows.

In general, it seems that it is sufficient to simply compare the contents of the original netlist 53 and the contents of the changed netlist 54 and extract a different point in order to find a changed portion of the connection. However, the present invention does not perform such an operation. The reason is that the graphic whose connection is desired to be changed is a graphic that is actually displayed on the CRT 7, and this graphic may not always match the contents of the original net list 53. That is,
When the wiring work is performed manually, a connection different from the original netlist 53 may be instructed to the computer 4.

Therefore, in the present invention, a net list is calculated backward from the graphic data list 56, and the calculated net list 56 thus obtained is compared with the changed net list 54 to extract changed portions.

The extraction of the changed portion is performed by a calculation net list creation function 41 and a comparison list creation function 42 in the computer 4.

First, the calculation netlist creation function 41 will be described. The calculation net list creation function 41 reads the contents of the graphic data list 55, calculates a set of component pins connected by the same wiring line, assigns a new net name to the set, and assigns this net name and this net Write the component pins to the calculated netlist. Add a description. The figure data list 55 describes the start point and end point coordinate values of all the wiring lines of the created printed board, and the calculation netlist creation function 41 uses the start point and the start point of this wiring line (L1, L2, L3, ...). By tracing the end point coordinate values, the connection of the wiring lines constituting each net can be taken out for each net. The position coordinate value of each component pin is stored in the component pin position list 52 of the disk 5.
And this is described in the graphic data list 55.
By referring to 52 or 55, it is possible to pick up component pins on the wiring lines of the extracted nets and form the calculated net list 56. The net names of the calculated nets thus obtained are given in the order calculated in the calculated net list 41 as described above, and are as shown in FIG. The contents in FIG. 6 correspond to the wiring lines shown in FIG. 3 (nets C0003 and C0004 are not shown in FIG. 3). 2, 3 and 6, the net names described in the original net list 53 are the following net names in the calculated net list 56. The contents of the calculated netlist 56 match).

A0001 → C0002, A0002 → C0001 Next, the comparison list creation function 42 will be described. First, the comparison list creation function 42 refers to the calculated net list 56 and the changed net list 54 shown in FIG. 6 and FIG. 7, and creates a list shown in FIG. it can. For example, when the calculation net list 56 (FIG. 6) is searched for the component pin IC1-3, this component pin IC
It can be seen that the net name of 1-3 is C0001. Next, IC1
Searching the changed net list 54 (FIG. 7) for -3 reveals that the net name of this component pin is B0001. In this manner, the calculated net list 56 and the changed net list 54 are searched for all component pins, and a list shown in FIG. The list shown in FIG. 8 can be created in a work area of a memory built in the computer 4, for example.

Further, the comparison list creation function 42 replaces the arrangement based on the net names in the calculated netlist 56 based on the list in FIG. That is, the list in FIG. 8 can be rewritten as shown in FIG. Add a description. Since the comparison list creation function 42 uses the calculated net name as a reference for sorting (arrangement), first, as shown in FIG. 10, component pins (IC1-3, IC3-2, IC3-8) with the net name of C0001 are assigned. ) Are arranged as a group (b). Similarly, component pins with the net name of C0002 are also arranged as a group (b). As described above, the comparison list creating function 42 compares the net names of the calculated net list 56 and the changed net list for each component pin, and groups the component pins by grouping the net names of the calculated net list 56. Listing 57 on disk 5
To be stored. From the comparison list shown in FIG. 10, the computer 4 can read information on the wiring line correction processing.

<A> Group (C) Although the group (C) shown in FIG. 10 is not shown in FIG. 9, the operation of deleting the wiring line is not performed for such a group (net). The reason is as follows. The net names of the component pins belonging to this group simply differ in sign between the case of the calculated net and the case of the changed net, and all the net names are in the state of being just replaced (C0009 → B0011). That is, in this case, it can be read that the connection state does not change and the way of naming the net simply changes. Therefore, the connecting lines for the component pins belonging to such a group (for example, C) do not perform the correcting operation.

<B> Group (a) In the form of the group (a) as shown in FIG. 10, the operation of deleting the wiring line is performed.

The form of “group (a)” refers to a group to which a single net name is given when the column of changed net name is viewed for each group of calculated nets in the comparison list of FIG. In the example of FIG. 10, a single net name B0004 exists in the changed net name. Computer 4 is the tenth
By searching the comparison list 57 in the figure, a group to which a single changed net name is assigned can be easily picked up. For such a group (a), a deletion operation is performed using the wiring deletion function 43.

This deletion operation will be described with reference to FIGS. 11 and 12.
FIG. 11 is an extract of the part (a) of FIG.

FIG. 12 (1) shows the contents of FIG. 11, and shows the state of the wiring line (net C0001) of the group (a) before the change. Looking at the changed net column in FIG. 11, a single net name B0004 is assigned to the component pin IC3-8. That is, before the change, IC1-3 and IC3-2
Means that IC3-8 belongs to the same net C0001, but component pin IC3-8 is separated from this net and belongs to another net B0004.

The wiring deletion function 43 for the nets in the form of group (a) uses the component pin (number
In the example of FIGS. 11 and 12, a wiring line connected to IC 3-8) is searched, and a wiring line from this component pin to the "first branch point" or to another component pin is displayed in the graphic data list 55. Remove from. That is, the wiring line indicated by the dotted line in FIG. 12 (2) is deleted. The above “first branch point” is the point S1 in FIG. 12 (2). A branch point is a point at which a wiring line is divided into paths in two or more directions.

In the example of net C0001 as shown in FIG. 12 (4), IC3-8
The first branch point seen from is point S2. Therefore, the wiring line indicated by the dotted line in FIG. 12 (5) is deleted.

An operation example in which the wiring deletion function 43 searches for a wiring line connected to a component pin (IC3-8) will be described. Component pin IC
The coordinate values of 3-8 can be easily known by referring to the component pin position list 52 (the coordinate values of the component pins are also described in the graphic data list 55). By searching the graphic data list 55 for a wiring line having the coordinate value of the component pin, the line connected to the IC 3-8 can be known. Then, the connection line connected to the end point coordinates of this wiring line is searched, and the connection path can be traced one after another on the graphic data list 55. A point where the number of connection paths becomes two or more is a branch point.

Then, the wiring deletion function 43 deletes the connection line reaching the first branch point from the graphic data list 55. After such deletion, the IC3-8 is connected to the IC1-5, for example, as shown in FIG. 12 (3). However, since this new wiring operation is out of the object of the present invention, the description is omitted.

In this group (a), the operation of the wiring deletion function 43 for deleting a wiring line from a component pin with a single net name to another component pin is simple. In this case, the connection before the change is, for example, the connection between IC1-1 and IC1-2, but this is changed to the connection between IC1-1 and IC1-4. At this time, I
A wiring line leading to C1-2 is searched for and deleted.

In short, the wiring deletion function 43 deletes a wiring line from a component pin that is unused or used for another net due to a design change.

<C> Group (b) The operation of deleting the wiring line is performed also in the form of the group (b) as shown in FIG.

"The form of group (b) means that, when looking at the column of changed net names for each group of calculated nets in the comparison list in FIG. 10, the changed net names are divided into a plurality of groups (e, f) (E, f) are groups composed of two or more component pins, respectively. In the example of FIG. 10, in the group (b), looking at the changed net side, the changed net name is divided into two groups (e) and (f). Each of these groups (e) and (f) has two or more component pins IC1
-8 and IC2-4, and IC2-5 and IC3-6.

The computer 4 can search the comparison list 57 in FIG. 10 to pick up a group including two or more changed net names. In the example of Fig. 10, group (a)
And (b) are picked up [group (c) has only one changed net name). Further, a group in which each change net has two or more component pins can be determined from the picked up groups.

In the example of FIG. 10, the group (a) is the changed net name B000
4 has only one component pin IC3-8 and is therefore excluded from the target. On the other hand, the group (b) has two component pins for each changed net name as described above.

And about the form of such a group (b),
A deletion operation is performed using the wiring deletion function 44.

This deletion operation will be described with reference to FIG. 13, FIG. 14, and FIG. FIG. 13 is an extract of the part (b) of FIG.

FIG. 14 (1) shows the contents of FIG. 13, and shows the state of the wiring line (net C0002) of the group (b) before the change. Looking at the changed net column in FIG. 13, the net B0002 includes component pins IC1-8 and IC2-4, and the net B0003 includes component pins IC2-5 and IC3-6. That is, before the change, IC1-8, IC2-4, IC2
2-5 and IC3-5 belonged to the same net C0002,
After the change, it means that the net C0002 has been divided into two nets B0002 and B0003.

The wiring deletion function 44 for the nets in such a group (b) form uses the wiring lines (L) connecting the different nets (B0002 and B0003) described in the changed netlist 54.
3) is deleted from the graphic data list 55. That is, the wiring line indicated by the dotted line in FIG. 14 (2) is deleted.

An operation example in which the wiring deletion function 44 deletes the wiring line L3 will be described. The wiring deletion function 44 picks up any one of the component pins belonging to the group (b) shown in FIG. 13, and reads the coordinate values into the component pin position list 52 or the graphic data list 55. When the coordinate value of the component pin, for example, IC1-8 is known, a wiring line having the coordinate value of the component pin is searched on the graphic data list 55. Further, the connection lines L1 to L9 shown in FIG. 14 (1) can be picked up by successively searching for the wiring lines connected to this wiring line. Further, the wiring deletion function 44 divides the wiring lines L1 to L9 thus picked up into blocks (see FIG. 15) for each branch point. The data of each block (block No., part pin, configuration line,
The connected group numbers are temporarily stored in, for example, 9 work areas of the memory in the computer 4.

In the example of FIG. 15, since it is assumed that the component pin IC1-8 is the starting point, the block No1 includes the line L1 connected to the IC1-8. The block is divided at each branch point of the wiring line, so the lines that make up block No. 1 are L1 and L2
It is. Blocks in the search direction connected to this block No. 1 are blocks No. 2 and 3.

The line constituting block No. 2 is L6, and the component pins included in this block are IC2-4. Block N
The block in the search direction to which o2 is connected is No3, but since it is already described at block No1, it is set to "none" here.

The line constituting block No. 3 is L3, and there is no component pin included in this block. Blocks in the search direction to which this block is connected are No. 4 and No. 5.

The lines constituting block No. 4 are L4 and L5, and the component pins included in this block are IC3-6.

The lines that make up block No. 5 are L7, L8 and L9,
The component pins included in this block are IC2-5.

Here, the wiring deletion function 44 can know that the component pins IC3-6 and IC2-5 are different nets from the IC1-8 and IC2-4 by searching the contents of the changed netlist 56. . Therefore, the blocks connected to blocks 4 and 5
The line L3 of No. 3 is deleted from the graphic data list 55. The above operation is performed when the wiring deletion function 44
The search can be performed by searching the description contents of the change netlist 54.

In short, when the old net is divided into two or more nets due to a design change, the wiring deletion function 44 deletes a wiring pattern connecting the two nets to be divided.

In the above description, the CAD for designing the printed board pattern
Although the apparatus has been described mainly by way of example, the present invention is also applicable to a CAD apparatus that creates a formal circuit diagram as traced from a circuit diagram drawn freehand.

<Effect of the present invention> According to the conventional CAD apparatus, all the patterns belonging to the net whose design has been changed have been deleted, so even if there is a pattern that can be used even after the change, this is uniquely deleted. Was. Therefore, after the design change, the lines that make up the net of the modified part must be routed from the beginning,
There was a problem that it took a long time to fix.

According to the present invention, in a net that has undergone a design change, if there is a wiring line that can be reused even after the change, this is left, and only the wiring pattern that must be truly corrected can be deleted, so that the wiring can be corrected quickly. it can. In this way, the correction is kept to the minimum necessary, so that the data on the printed board before the correction can be used as it is. Therefore, there is also an effect that documents and printed data relating to a printed board (circuit diagram) that have already been created can be used as they are.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a CAD apparatus according to the present invention, FIGS. 2 and 3 are diagrams showing the relationship between a net (list) and component pins, and FIGS. 4 and 5 are graphic data lists. FIG. 6 shows a calculated net list, FIG. 7 shows a changed net list, FIGS. 8 and 10 show a comparison list, and FIG. 9 shows a changed list. FIGS. 11 and 12 are diagrams illustrating the operation of the first invention, FIGS. 13 to 15 are diagrams illustrating the operation of the second invention, and FIGS. FIG. 16 is a diagram for explaining the operation of the conventional device. 4: Computer, 41: Calculation net list creation function, 42: Comparison list creation function, 43, 44: Wiring deletion function, 52: Component pin position list, 54: Changed net list, 55: Graphic Data list, 56 ... Calculated net list, 57 ... Comparison list.

Claims (2)

(57) [Claims] A graphic data storage unit (5) in which coordinate values of component pins, start point coordinates and end point coordinates of line segments forming wiring lines connecting the specified component pins and the component pins are written.
5) In order to change the contents of the graphic data storage unit, a net name given to each group of component pins (hereinafter referred to as a net) to be connected by the same wiring line and a component pin of each net are written. A first storage unit (54) and a set of component pins connected by the same wiring line are calculated based on the contents of the graphic data storage unit, and a new net name is assigned to the set. Means (41) for writing the component pins of the net into the second storage unit (56); comparing the net names of the first storage unit and the second storage unit for each component pin; A list creating means (42) for creating, on the storage device (5), a list (57) in which the component pins are arranged in groups for each net name; Search for wiring lines connected to component pins with net names, and CAD apparatus having a means (43), a to delete the wiring line from the pin until the first to the branch point, or other component pin from the graphic data storage unit. 2. A graphic data storage unit (5) in which coordinate values of component pins, start point coordinates and end point coordinates of a line segment forming a wiring line connecting the designated component pins and the component pins are written.
5) In order to change the contents of the graphic data storage unit, a net name given to each group of component pins (hereinafter referred to as a net) to be connected by the same wiring line and a component pin of each net are written. A first storage unit (54) and a set of component pins connected by the same wiring line are calculated based on the contents of the graphic data storage unit, and a new net name is assigned to the set. Means (41) for writing the component pins of the net into the second storage unit (56); comparing the net names of the first storage unit and the second storage unit for each component pin; A list creating means (42) for creating a list (57) in which the component pins are arranged in groups for each net name on the storage device (5), and the net name of the first storage unit in each group is Divided into multiple groups, each group consisting of two or more component pins If it is a means to remove the wiring lines connecting the different nets each other as described in the first storage unit (L3) from the graphic data storage unit (44), CAD apparatus having a.