CSE664 – A Small Tutorial of Magic and IRSIM

1. Start 2. Basics 3. Cells 4. Errors 5. Simulation 6. Pads 7. FAQ

Add the following three lines at the end of your ".login" file in your home directory, then exit your account and login again.

setenv CAD_HOME /usr/local/magic

set path = ($CAD_HOME/bin $path)

If you need to use Magic from a remote unix workstation, say "garfield":

"xhost +" on garfield

telnet to a local workstation, say "apollo"

"setenv DISPLAY garfield:0.0" on apollo

"magic" on apollo

Manual can be found at /usr/local/magic/doc.

Remember to put a ":" before you issue any command, and you will like to get familiar with macro, which is a one character shortcut for command, to expedite your design.

Also always put your mouse pointer inside the graphic window, because most commands need you to do so. Here is an example of the design of an inverter.

1. Paint:

                :paint layers

After you start up Magic, you will see a graphic window. Inside the graphic window, there is a box with white edge. You can use the left and right mouse button to locate the box. When you issue the paint command, you will paint material inside this box. You can use the middle mouse button to expedite painting if you have already paint some material in same layer or color. Press the middle mouse button on the color you want to copy, the area under the current box will be painted with the same color. You can also use this method to erase something, just copy color from blank area will erase anything under the current box.

2.Grid

                :Grid or just press g

3.Zoom

                :Zoom ratio

You can also use macro "z" to zoom the layout so that the area inside the current box just fill the whole window. Macro "Z" means to zoom out with ratio 2.

4.Undo and redo

                :undo or macro "u"

                :redo or macro "U"

5.Select

Put the mouse pointer on any layer you want to select, then issue the command:

                :select or macro "s"

If you use select command several times, Magic will select more adjacent connected area, which have same voltage. So you can use this command to check the connection relation of the layout. If you want to select all layers inside the current box, use the commad:

                :select all or macro "a"

After selection, you can issue one of the following command:

                :delete or macro "d"

                :move [direction [distance]] or macro "t"

                :copy or macro "c"

                :upsidedown

                :sideways

                :clockwise [degrees]

6. Label

You have to label a layer if you want to analysis it in simulation. First select any layer, then issue the command:

                :label position

Position may be any of north, south, east, west, top, bottom, left, right, up, down, center, northeast, ne, southeast, se, southwest, sw, northwest, nw.

You can also erase a label by first select the material then issue the command:

                :erase label

7. Save and load command

Before exit Magic, you need to use save command to save the layout.

                :save or :save filename

Do not add .mag extension to filename because Magic will automatically add it.

8."Wiring" tools

You can use "wiring" tools to add leg to existed material or make contact between different layers easily.

Steps to add leg:

Switch to "wiring" tools.

Click the material from which you need to paint leg with left mouse button.

Click the destination point with right mouse button to paint the leg.

Steps to make contact:

Normally you can using "box" tools to paint material. Press space key to switch to "wiring" tools. Press space key three times again will bring you back to "box" tools.

First paint the area with two layers you want to make contact with, make sure the two layers are overlapped.

Switch to "wiring" tools.

Click the area you need to make contact with left mouse button. Magic will display a box to indicate where it will put the contact.

Then you use middle mouse button to click on the area and Magic will make a contact for you.

After you designed the layout for a typical component, you can use it as a cell to build other circuit. Now suppose we have designed the inverter and save it as inverter.mag, we can use it as a cell to make another circuit. Here is an example file top.mag using two inverters use subcell.

Open magic to edit a new file called top.mag:

In Magic, issue the command below twice:

                :getcell inverter

Then put these two inverters together, select them and issue command to see the structure of inverter:

                :expand or macro "x"

You can unexpand the cell with command:

                :unexpand or macro "X"

If you need to make an array of cells, use the command:

                :array xsize ysize or

                :array xlo xhi ylo yhi

You can check if there is an error and the reason in any area. First putt a box on the area you want to check and issue the command:

                :drc why

If there are warnings, you can check the reason with the command:

                :feedback why

Do not worry if Magic complain two Vdd! or two GND! are not connected together, because IRSIM knows they are connected.

We will use the top.mag file discussed above as an example to simulate.

1. First you need to label every thing you need to observe in Magic in top cell level. Make sure you label on some material in top cell level, and you should see a sentence like below:

Move label "XXX" from space to metal 1(or other material)

2. Issue the extract command:

                :ext

You will get a file called filename.ext.

3. In Unix shell, issue the command:

                ext2sim filename

You will get a file called filename.sim.

4. Now you need to get the SCMOS technology file cmos.prm and put it in your working directory.

5. in Unix shell, issue the command:

                irsim cmos.prm filename.sim

Now you are in IRSIM, you can use "l" and "h" to give low or high voltage to node, use "ana" command to watch the waveform, and use "s" command to simulate.

Below is a simple example of simulation process:

                llama% irsim cmos.prm top.sim

                *** IRSIM version 9.4.1 ***

                info: SU format --> using S/D attrs to compute junction parasitics

                Warning: Aliasing nodes 'GND' and 'Gnd'

                top.sim: Ignoring lumped-resistance ('R' construct)

                Read top.sim lambda:1.00u format:SU

                7 nodes; transistors: n-channel=2 p-channel=2

                parallel txtors:none

                irsim> l GND!

                irsim> h Vdd!

                irsim> l D

                irsim> ana D Q Inverter_1/Input

                irsim> s

                time = 10.00ns

                irsim> h D

                irsim> s

                time = 20.00ns

                irsim> q

The output is as below:

Later on, you'd like to type and save all your command into a text command file. Then in IRSIM, you can execute all commands like below:

                @ command_filename

To print out the waveform, click the "print" menu and select the "print to file" submenu. It will ask you for the target filename at the bottom of window, press ENTER to accept default filename. Then use "lpr" command in Unix to print the result.

MOSIS web site

1. Download the pad files, pads.tar, and the documentation file into an empty directory

In that directory: tar xvf pads.tar

Use 40pin_stuffed.mag as the frame file. For each pad, there are 'in', 'inb', 'out' and 'en' signals.

2. You can ftp these files, /pub/mosis/cell-libraries/scn12-pads and /pub/mosis/cell-libraries/scn12_pads.doc, directly from the MOSIS site (ftp.mosis.org)

1. How to printout a Magic file:

In Magic, issue the command

:cif

You will get a file with cif extension. Then in Unix shell, type the command to print the layout:

pplot filename.cif | lpr

When the program prompts out:

Do you want a plot (Yes/No/ChangeScale) [y] ?

Press ENTER to printout the layout.

You can also print the layout to a postscript file and print out the file later.

pplot filename.cif > filename.ps

lpr filename.ps

2. I can not load the tutorial files:

In Magic, issue the command:

:addpath ~cad/tutorial

Now you can load the tutorial files.

If you do not wish to issue this command every time, you need to create a .magic file in your home directory and put this command into it. So this command will be executed when Magic is started.

3. IRSIM can not find the node I have labeled:

First, if several nodes you labeled are connected together, Magic will only keep one label. Sometimes when you make mistake to connect some nodes to GND! or Vdd!, you can not see this node in IRSIM.

Second, if you want to see the node in top cell level, make sure you paint some material on top cell level and label on it. If you just label in top cell level but on layer in subcell, Magic will not label it correctly.

You have to use the format below to access label inside a subcell:

cell_name/local_label