[Pixel]<Chipndale>6.1>CDDoc23>ChipNDaleDoc.tioga!1

ChipNDale

FOR INTERNAL XEROX USE ONLY

ChipNDale 2.3

An interactive editor and database for VLSI designs

MOS Designer's introduction

Release 2.3

Ch. Jacobi, Kim Rachmeler (August 18, 1986)

Filed on: [DATools]<DATools6.1>CDDoc23>ChipNDaleDoc.tioga

Abstract: ChipNDale is an interactive graphic layout tool made to run in Cedar. This document is an introductory reference for users creating or editing VLSI designs; there will be other documentation describing additional utilities like creating checkplots, masks, or CIF output, and doing design rule checking. Programmers who want to access ChipNDale from a program should read the additional documentation available for these purposes.

XEROX Xerox Corporation
Palo Alto Research Center
3333 Coyote Hill Road
Palo Alto, California 94304

For Internal Xerox Use Only

Contents

0. Introduction

1. General Definitions and Descriptions

2. ChipNDale Viewer Commands

3. ComandTool commands

4. User Profile Options

5. The Outside World

6. ChipNSil

ChipNDale's documentation is divided into several main files:

ChipNDaleDoc.tioga This text. Reference guide for interactive use of the ChipNDale editor for the technologies CMos, NMos, and ChipNSil.

ChipNDaleIntroduction.tioga An introduction for the very first hour of interactive ChipNDale usage. Read that documentation and play with ChipNDale at the same time.

ChipNDaleToolsDoc.tioga Reference guide for interactive use of some other ChipNDale related tools. Other tools will have separate documentation, stored with the tool directly. This document tells you for example how to make hardcopies.

ChipNDaleProgramsDoc.tioga Reference guide for creation of ChipNDale designs from programs. That guide is a mixture of a guide for tool creation, technology creation and simple creation of particular ChipNDale designs from programs.

CDCrib.tioga Crib sheet.

ChipNDale-RegistrationDoc.tioga To be used by implementors. Meta documentation about registered features telling where the real truth is stored.

ChipNDaleMessagesDoc.tioga A unstructured list of messages about ChipNDale.

Further tools may have their own documentation. Since ChipNDale is an open system it is not posssible to completely list all its available tools. Uncomplete list:

CDExtrasDoc.tioga Doc for some extra modules.

0. Introduction

0.1. History

ChipNDale1 is the ultimate interactive VLSI layout editor written in Cedar. It is normally used interactively, but all its operations can be accessed by other programs.

In early design stages called Chipmonk II, ChipNDale is the Cedar successor to Chipmonk, an interactive layout editor written for the Alto world. But although ChipNDale looks a good deal like Chipmonk, there are quite distinct dissimilarities. Like Chipmonk, combinations of keyboard and mouse commands allow creation and modification of both primitive (contacts, transistors) and constructed (cells) objects. Multiple views of a design are available on both the color and B&W displays. ChipNDale can read in old Chipmonk files and some ChipNDale designs can be written out in Chipmonk format. Unlike Chipmonk, ChipNDale incorporates the concept of "technology independence", the idea that separate technologies (NMOS, CMOS, PC boards, etc.) do not interfere with the basic ChipNDale kernel, nor do they interfere with one another. New technologies may be created with their own definitions of commands and structures, allowing ChipNDale to expand to accommodate new methods and applications.

There are three main sections to the ChipNDale documentation. The first is the user's manual, the file you are currently reading. The second is a guide to the additional tools that can be loaded along with ChipNDale; this document can be found in the file ChipNDaleTools.tioga. The third section is a set of hints for programmers of ChipNDale clients; this file can be found under ChipNDalePrograms.tioga.

The rest of this introduction will provide you with step-by-step information to start ChipNDale and read in design files. The rest of the document is intended as a reference manual; use the "Levels" button to scan the document for the general section you are interested in reading. The amount of descriptive detail increases with the number of visible levels. The notes in small print at the deepest nested level are usually examples or explanations that the inexperienced user might need. The "Find" button can also be useful if you are searching for a particular topic.

1 The name ChipNDale comes from neither the fine furniture in England nor the fine figures in LA but from Chip 'n Dale, the two furry characters created by Walt Disney (two chipmunks -- Chipmonk II, get it? wrong!) Subnote: "Chip <-> Dale" also referred to the split between a technology independent kernel and all the add-ons, technologies and commands.

0.2. How to start

Installing the program

Bringover /DATools/DATools6.1/Top/CDDesign23.df

This DF file will equip the machine with all the information it needs to run the NMOS, CMOS-A, CMOS-B, and ChipNSil versions of ChipNDale. The current version is called 2.3 and runs on top of Cedar 6.1.

Be carefull about what subdirectory to use: ChipNDale really doesn't like it if the technology and the the kernel run in different subdirectories. It is usually best to create a separate subdirectory for ChipNDale; this allows you to remove it easily when you want to upgrade to a new version. If you use ///Commands/ everything works, but you have no way to remove ChipNDale anymore except by deleting all in ///Commands/.

Start the program

To start up a session of ChipNDale (in the subdirectory containing its files, or in any subdirectory if ChipNDale is in ///Commands/) you can use the following load files:

% CDCMosA or
% CDCMosB or
% CDNMos or
% CDSil

These load files will load the ChipNDale program and create a Terminal monitor viewer (hereafter referred to as "Terminal"). Terminal keeps a log of all the commands issued concerning ChipNDale; it is where you will look to find information about what ChipNDale is trying to execute and how that execution is progressing. Some technologies might have load files which make the start with commandfiles superfluous, however, using the commandfiles might be faster.

When you use ChipNDale for the first time, just go ahead. Playing with ChipNDale is not dangerous: when ChipNDale reads in an existing design it will not overwrite the file unless you explicitly issue an output or save command. When you are an old Chipmonk user: ChipNDale is able to read in Chipmonk files; look in the documentation about additional tools.

Get a design to work with

To get an existing design up on the screen (after the program has been started) , use

% CDOpen <optional name of a ChipNDale design file>

ChipNDale design files contain the technology of their design; However, the code handling that technology must be loaded before issuing the CDOpen command. If no filename was given to the read command, Terminal will respond with the request to type a file name in. The file may either be present locally or on one of the file servers; default extension is ".dale". You do not need to type in the extension.

To start up a fresh design use one of the commands:

% CDNewCMosA or
% CDNewCMosB or
% CDNewNMos or
% CDNewSil or
% CDOpen -<technology name>

These commands will display the design (or new viewer) on the screen.

1. General Definitions and Descriptions

1.1. The Terminal

The Terminal viewer is one of the main communication points between the user and ChipNDale. Terminal not only keeps a log of commands executed but also prompts the user for input and displays error messages. There is only one Terminal for any invocation of ChipNDale, regardless of the number of designs displayed.

1.2. Technologies

One of ChipNDale's main features is its ability to adapt to new technologies without changes to the core of the program. This feature is called "technology independence"; it means that new fabrication techniques or applications can be described in modules and plugged into the existing system. But this capability also means that the user must make sure that the appropriate technology is loaded so that ChipNDale can access features unique to that technology. For MOS designs, ChipNDale distinguishes between the NMOS, the CMOSA, and the CMOSB technology.
The "technology independence" of ChipNDale goes that far that even a technology ChipNSil is available, describing schematics or arbitrary drawings.

CMOSA: The old cmos of 1983-1985; it is kept so people can still read in older designs.

CMOSB: The new cmos of 1986; it has nicer features then CMOSA, but atomic objects which have been declared as unsave for the Dragon project have not made it into CMOSB.

1.3. Design

A design is what a designer creates; it is the unit used to be stored in files, and also the unit used in the synchronization. Every design is in a particular technology and consists of some geometry and a directory. The design is also the unit which is put into one file usually.

1.4. Objects

Primitive objects are the "atoms", if you will, of the ChipNDale world. The existing primitives are transistors (straight and angle), contacts (buried and butting), and wires.

Composite objects are cells, repetitions or imports. These are the building blocks of the more complex structures used to construct designs. All the composite objects must be listed in the design's directory. Cells are the most basic building blocks.

The types of objects which can be included in a design are specified by the technology. However some types of objects, cells and rectangles, exist in all technologies.

1.5. Additional Tools

ChipNDale makes it easy to write additional tools, causing a large variety of extra utilities to spring up around the core program. It is not possible to describe all additional tools in this document; you can find that description in ChipNDaleTools.tioga. The list of additional tools starts with "design rule checking", "making checkplots", "cif generation", "mask generation"...

1.6. Tip Tables

Often used as the real truth of the user interface, users are invited to browse the tip table. The tip table is alphabetically sorted and it has comments. ChipNDale typically uses two tiptables, one which describes the general ChipNDale user interface, and a second one which describes the technology dependent commands; But ChipNDale lets you nest an arbitrary number of tip tables.

2. ChipNDale Viewer Commands

2.0. In General

ChipNDale commands are grouped such that those most frequently applied use the lefthand side of the keyboard. This grouping allows easy finger placement without having to move your right hand away from the mouse. This speedy access, however, has outweighed mnemonics, which is why "Q" draws a transistor, not "T". Infrequently used commands have been shuffled off to the righthand side of the keyboard. Commands are executed in the ChipNDale viewer with the input focus. If the viewer does not have the input focus, the cursor will appear as a fat arrow pointing down. Click any mouse button to obtain the proper cursor.

The mouse buttons are ordered such that the middle button controls drawing objects, the left and right buttons control modifications. Drawing only occurs when the middle button is pressed or held down; alterations only occur when the left or right button goes up.

Most commands that affect selected objects can be performed with either the left or the right button, or with the CTRL key; the left button only affects the object pointed to, the right button or CTRL applies all currently selected objects. These commands are indicated in the documentation with the choice {Left or Right or CTRL}, meaning that the command will be applied to a different set of objects depending on the button used. The CTRL key can be applied only to execute those commands which do not depend on a mouse position.

The following commands refer to the default CMOS and NMOS ChipNDale tip tables. All of the technology independent commands work also for ChipNSil; There are some paragraphs describing ChipNSil particularly.

2.1. The Pop-up menus and the control panel

Pop up menus

ChipNDale has real many commands, more than you are willing to remember. Pop up menus allow you to call commands, without having to know lots of exotic key combinations. There are many pop up menus available, and the menus can get additional entries when more programs are loaded. You can always try what commands a pop up menu has; mouse clicking outside of it discards the menu. To get a pop up menu, push the space key together with its letter key.

<G>-<Space> the global menu; allows to call other menus

<B->-<Space> the text and properties menu

<C->-<Space> the cell menu; creation etc of cell

<D->-<Space> the directory menu; get an object, clean the directory...

-<Space> the IO menu

<K>-<Space> the DRC menu

-<Space> the program menu; call of additional programs.

<O>-<Space> the other program menu; call of additional programs.

<T>-<Space> the transformation menu; mirror and rotate

<N>-<Space> the names and properties menu

<V>-<Space> the viewer menu

<S>-<Space> the special commands menu

-<Space> the generator setup menu

<M>-<Space> the draw mode menu

<X>-<Space> the imports menu

<,>-<Space> the simplification menu

<.>-<Space> the ticks menu

</>-<Space> the grid menu

<->-<Space> the curves menu

Some few pop up menus are reserved for commands which need a position as parameter, these commands obviously need a mouse interaction to make the pop up menu appear.

<G>-<Middle> global menu; allows to call other menus which need a position

<K>-<Middle> drc menu; drc options which need positions

-<Middle> another program menu; programs executed on a rectangular area

<S>-<Middle> special commands which need positions

<H>-<Middle> the hard copy menu; the called hard copy programs do all want a
rectangular area as input parameter.

-<Middle> the generator call menu.

Note: the pop-up menus can be altered dynamically by client modules while ChipNDale is already running; The general documentation can not accurately document all entries, but contains the most important entries .

Control panel commands

The control panel is a graphical method of changing layout parameters. Every design has a control panel associated with it; The control panel allows the designer to select default values, mainly the layer in which he wants to draw, but also some other modes. The panels also have some technology dependent entries.
The control panel can be scrolled.

Commands on top of integer or layer values:

Control panel commands are executed by clicking mouse buttons on top of the text (not the value).

Left: increment value

Right: decrement value

CTRL Left: double value

CTRL Right: half value

Middle: (when done over a layer description)

selects this layer as default for drawing wires

<SHIFT>-

<mouse key>: shows a pop up menu, allows entry of arbitrary values.

Top line commands:

new view:

The new view command allows the user to create or split a viewer on the associated design.

save:

Save the design on a file; this command is for conveniance only.

menu:

The root pop up menu for all the commands which do not need actual positions.

help:

Displays ome help information.

Technology dependent commands:

There are several buttons on the panel referring to modifications to transistors. Both NMOS and CMOS panels have width and length buttons for changing the default measurements in the horizontal and vertical dimensions respectively. The NMOS panel has three additional buttons. The 'implant' button changes the type of transistor according to the following codes:

NMOS transistor codes

weak allows access to weak implants, a feature which you probably don't want to use.

WEAK IMPLANT MEANING

0 0 enhancement

0 1 depletion load

1 0 threshold = 0

1 1 weak depletion

The other two extra buttons change the width and length of pull-up transistors.

2.1. Simple Selection

Select Single Object

Left Point to desired object and hit the Left mouse button. All previous selections will be removed and this object will be selected. (Note: just the condition of being selected is removed, not the object itself!)

Fine point: If the mouse position is exactly the same as before, and no other key is pressed, the selection will rotate through the possible objects at that point; otherwise the command will reselect the last selected object under the mouse position. This enables you to select objects completely obscured by other overlaying structures.

Select Multiple Objects

Right Selections made with the Right mouse button will be added to the collection of previously selected items.

Deselect Object

<ESC>-Right Point to a selected object, hold down <ESC> and hit Right. Selection will be removed.

Fine point: <ESC>-Left will deselect all objects.

Change selection

<SPACE> If you are selecting an object but have not yet let the mouse button up, you can change your choice by keeping the button down, moving the mouse to the new object and hitting <SPACE>. This change in midstream will also work even if you are about to execute a command on the selected object.

For example: Say you want to rotate something. You press R, point to the appropriate object and press the Left mouse button. As soon as you let the button up, the command will be executed. But wait! You really wanted the object just to the right! No problem. Keep the mouse button and the R down, move the cursor to the new object, and hit <SPACE>. The selection will be switched to the new pointed objected. Now when the mouse button is released, the new object will be rotated (either in place of or in addition to the old object, depending upon whether the Left or Right mouse button was used).

2.2. More Advanced Selection <<***>>

Area Select/Deselect

There are two ways to handle area selections, the common area selection selects (or deselects) all objects which are completely included in a rectangular area. Use the common selection commands, but drag the mouse while the button is down.

The other method of area selection handles every object which touches the designated area.

<SWAT>-Left other area select

<SWAT>-<right-SHIFT>-Left other area de select

Select All

<SPACE>-<right> selects everything in the current design

Select Entire Layer

<LF>-{Right or Left} all of the objects belonging to the current layer will be selected or added to the selection.

2.3. Drawing objects

Wires

Middle Pressing the Middle button and moving the mouse draws a wire of the current layer with the current width, releasing the button confirms the position and length of the wire.

<SHIFT> Hitting <SHIFT> while drawing a wire draws the first segment of the outlined wire.

<SPACE> Hitting <SPACE> while drawing a wire flips the orientation of the direction the wire bends.

<ESC> Stops the wire drawing process.

Note: The current layer can be changed with either the keyboard or the control panel, the width can be set only through the control panel.

Note: When you statrted drawing a wire but think differently, press ESC to discard the outlined wire.

Choosing a layer

All the layer commands use keys in the top row.

<ESC>-Middle Clicking the middle button while holding down <ESC> will set the current layer to be the same as the layer of a pointed object, if it has a unique layer.

Change layer by hitting the associated layer number key. (CMos and NMos only). The control panel can also be used to change layers; note that the order of the layers associated with the keys is the same as the order listed in the control panel.

CMOS

<1> diffusion:

default N+, with <SHIFT> P+

<2> poly

<3> metal

<4> diffusion contact:

default P+ to N-well, with <SHIFT> N+ to P-well

<5> N-well

<6> 2nd layer metal

<0> comment (CMOS-B only)

In general, if the <SHIFT> or <LOCK> key is down, everything is done in the P-diffusion world; <LOCK> up indicates N-diffusion. You can change between pdif and ndif just by switching the position of the <LOCK> key without hitting <1>.

Note: NMOS uses <4> for 2nd layer metal, it has no wells or well contacts.

ChipNSil layers are select with the control panel.

To change the layer of an already painted object, use '-<left or right>.

Transistors

(CMos and NMos only)

Q-middle Draw a n-transistor (with SHIFT or LOCK: a p-transistor)

W-middle Draw an angle n-transistor(with SHIFT or LOCK: an angle p-transistor)

Contacts

Contact commands use the same keyboard keys as the layer commands plus the middle mouse button; the contact is made between the indicated layer and metal. The command is executed by holding down the appropriate numeric keys while hitting the middle button. (CMos and NMos only).

Middle mouse button while:

<1> N+ to metal, with <SHIFT>: P+ to metal

<2> poly to metal

<3> Butting P+ to poly and metal; with <SHIFT>: N+

<4> P+ to substrate, with <SHIFT>: N+ to N-well

<6> metal to metal 2

<1>-<2> Buried N+ to poly; (There are no P+ buried contacts)

<1>-<2>-<3> Butting P+ to poly and metal; with <SHIFT>: N+

This command is supposed to remind you of the three layers used in a butting contact; everybody will probably use the simpler <3>-Middle command though. I know I would.

Note: NMOS uses <4> for 2nd layer metal, therefore <4> for a metal to metal 2 contact; there are no substrate contacts.

Drawing objects by name (from the directory)

C-Middle Draw object, placing origin at current cursor position. Terminal will prompt for name of the object to be drawn.

2.4. Simple transformations

Move by a vector

<CTRL>-{Left or Right} Move selected object(s).

If done with the right button, moves entire collection of selected objects relative to the former cursor position as indicated by the vector drawn on the screen when moving the mouse. The left button reselect a single object and moves only this object.

Move an incremental step

A-{Left or Right or CTRL} to the left.

S-{Left or Right or CTRL} to the right

W-{Left or Right or CTRL} up

Z-{Left or Right or CTRL} down

Note that the four keys A S W and Z are arranged in the same relative positions as the directions they move the selected object(s). The size of the step can be set by the control panel.

Copy

<SHIFT>-{Left or Right} Copy selected objects positioned according to the drawn vector; the simple copy is similar to a move save for an additional <TAB> -- however, the step moves do not have a corresponding copy version; they would not make sense.

If done with the right button, copies entire collection of selected objects by choosing an origin with the left mouse button, holding that button down, and moving the cursor to the desired destination. The left button only copies the single selected object.

Rotate and mirror

R-{Left or Right or CTRL} Rotate selected object(s) by 90 in a clockwise direction, the bottom left corner remains fixed.

T-{Left or Right or CTRL} Mirror selected object(s) across the vertical axis

E-{Left or Right or CTRL} Mirror selected object(s) across the horizontal axis

Note that rotation and mirroring can also be done with the Transform pop-up menu, <SPACE>-T.

Rotation is the R command; for mirroring E and T were selected because they are located next to the "R" (rotate) key and have symmetries appropriate to their function.

Delete

D-{Left or Right or CTRL} Delete selected object(s)

Un-Delete

D-ESC Undelete last deleted object(s). Undelete may be repeated some times.

2.5. Stretching objects

Stretch

{A, S, W, Z or none}-<TAB>-{Left or Right} Note that stretching is very similar to the moves; instead of moving the object, only the pointed border is moved, the object is stretched. Therefore, the stretch commands are identical to the move commands except, that a modifier key, <CTRL> is used. The letter A, S, W, Z or Q specify the direction and the amount, as in the moves.

You must be pointing to an edge of a selected object each time the mouse button is pushed. The pointed edge will be stretched.

For now, angle transistors stretch in a crazy way, please be forgiving.

2.6. Some exotic but useful or necessary commands <<***>>

Stretchy move

{<TAB>-<CTRL>-A, S, W, Z}

{<TAB>-<CTRL>}-{Left or Right}

Stretchy move is a special move which maintaining primitive connectivity; The commands are like the moves, except the TAB modifier key.

Stretchy move is implemented in a strictly geometric way and does not understand the electrical behavior... be gentle on imperfection.

Measuring distance, counting objects, information about an object

<CTRL>-Middle

-- Click the middle key quick when <CTRL> is down: you get information about the selected objects.

-- Draw a vector by holding down <CTRL> and the middle button while moving the mouse. When the mouse button is released, Terminal will display the values of the end coordinates and the distance between them.

Yes, these two commands use the same keys, only the time scale is different.

Split a wire

|-{Left or Right} Split wire(s) along its/their width by holding down both the "|" key and the appropriate button while moving the mouse. Command is executed by lifting the mouse button.

Move to grid

/-{Left or Right or CTRL} Move object(s) to a grid position

Did you notice that / is the general grid key?.

Grow by width

G-{Left or Right or CTRL} Grow wires in length direction by the amount of their width.

This is handy to draw boxes when working with a coarse grid. To shrink back to grid positions use the split command and delete the small piece; I do nto believe that you really want to shrink to other than grid positions.

Interrupt the drawing

<ESC>-<LF> Hold down a few seconds! Interrupts the drawing, of all viewers, immediately after the command is accepted

Abort a command

<ESC>-<DEL> Aborts the current command; works at least if the implementation of the current command is kosher and asks for the abort flag... . Of course, short commands do not ask the flag, but the abort command at least flushes the command queue.

An analogue is using <DEL> to abort an input on Terminal.

Special commands menu

<Space>-S The special commands menu is a catch-all menu for odd commands which don't really fit in elsewhere. It includes commands such as undelete, abort command, and statistics, among others.

<middle>-S The special commands menu with commands which depend on particular position or area.
It contains comands for setting or defaulting the interest rect of the pushed in cell.

Debug command

<^>-middle Enter the debugger. Shows first a pop up menu to decide whether the locking of the design should be released. It is conveniant to release the lock, this allows to issue other commands while the debugger still has a handle into the design. However, if the lock is released the debugging actions are not queued properly and it is up to the designer to prevent any problems due to concurrency.

The debugger is called from a procedure which allows you to inspect easily the selected object, it's specificRef field, the instance, the design or th command. A special procedure Include may be called from the interpreter. This procedure includes any object or instance into the design. It is up to the user to make sure an included thing is correct.

It is perfectly save to either abort or proceed a debugger created with the debug command.

Arrow command

<A>-middle Puts down an arrow at this position. (Some commands might depend on the position pointed to by this arrow.)
Don't rely on the arrow position over multiple commands, some commands might move the arrow position implicitely.

<ESC-A> Remove the arrow

2.7. Viewer commands

Change scale

"<", ">" Hitting <<> increases magnification; hitting <>> decreases it. It is easier to remember these commands by looking at the upper case options on the keys, but of course the real keys are <.> and <,>.

Or, if you want to be visual in remembering the commands, note that the "<" starts small then gets bigger, hence it makes objects appear bigger. In the same way, ">" starts big and ends small, making objects appear smaller.

Interrupt drawing

<ESC-LF> Hold down for about 2 seconds. Will interrupt the drawing on all ChipNDale viewers. This command is usefull to interrupt the drawing if a complex design is drawn in excessive detail, which might need hours... The drawing can be repeated simply by zooming or paning.

Change position, pan viewer

<SPACE>-Middle Moving the mouse while holding down both the <SPACE> key and the middle button draws a vector on the screen. The view of the design will be moved in proportion to that vector when the mouse button is released.

Show a particular area, zoom in viewer

<SPACE>-Left

<SPACE>-<SHIFT>-Left Drag a box to define an area. The view of the design will be scaled and moved such that this box will be displayed. This displays the drawn area on the viewer; together with SHIFT it choses another viewer.

<SPACE>-Left (not with <SHIFT> !) can be un-done with <SPACE-ESC>.

Show position of other viewers <<***>>

<V>-Middle Shows the positions of the other viewers.

View top cell <<***>>

<SPACE>-<TAB> Cause the viewer position and scale to change so that all objects of the top pushed cell are visible on the screen.

View in previous scale

<SPACE>—<ESC> Cause the viewer position and scale to change back to a scale used before.

View all selections <<***>>

<SPACE>—<CTRL> Cause the viewer position and scale to change so that all selected objects are visible on the screen.

Changing the simplification treshold

Use the simplification menu either directly or through the viewer menu.

The simplification treshold can also be changed on a per cell base (The actual treshold value is a product from the viewer and the cell treshold value). See the cell menu for this command.

2.8. Cells

Note that these commands can also be accessed through the cell pop-up menu, <SPACE>-C. Drawing cells is not a special command but like putting down any named object which is in the directory: use the C-Middle command.

Create cell

X-C-Middle Create a new cell from the set of all selected objects. Terminal will prompt for a unique cell name.

This double key command is easy to remember: X is just the neighbour key to C, which is used for all cell related commands.

Expand (Flatten) cell

Use the cell pop up menu. (C-Space)

Push-Pop

C-{Left or Right or CTRL} Push into cell: the rest of the design will be grayed.

C-<SHIFT> Pop out of cell. The user has the option to ignore the edits, to create a new cell, or to really edit the pushed cell (then the edits are propagated to all instances of the cell).

X-{Left or Right or CTRL} Push into the cell which is designated by the selected object. E.g. if the selected object is an icon, this pushes into the corresponding schematic.

The push command may also be executed for objects other than cells. A new cell with corresponding geometry will be created. On the pop out, the user has the option whether the original object should be replaced by the corresponding edited cell.

Interest rect

The interest rect denotes the interesting area of an object. It has been defined to denote an artificial cell boundary for routers and module generators. The interest rect can be defaulted or set to any particular value. (Use the "special commands with rectangle" menu; S-<middle> ).
The interest rect should not point outside the area where ChipNDale is drawing. Even if except drawing all else works correctly, this is condidered erronous usage of ChipNDale.