Spectrum Software
Industrial Strength Simulation




Spectrum Software has released Micro-Cap 11, the eleventh generation of our SPICE circuit simulator.

For users of previous Micro-Cap versions, check out the new features available in the latest version. For those of you who are new to Micro-Cap, take our features tour to see what Micro-Cap has to offer.






I am having issues with permission denied errors both in the schematic and in the analysis. When I double click on an NPN transistor in the schematic, I receive the following error message:

Permission denied C:\MC9\LIBRARY\NOM_LIB.INX

Error occurred while trying to write index for file C:\MC9\LIBRARY\NOM.LIB.
File: C:\MC9\DATA\circuit1.cir.

Then when I try to run a transient simulation on this circuit, the following error occurs:

Permission denied C:\MC9\DATA\circuit1.TNO

File: C:\MC9\DATA\circuit1.cir

How do I get past these errors?


The permission denied error occurs when Micro-Cap is unable to perform the necessary read or write to the specified file. In most cases, the inability to perform a write operation is what triggers the error. There are two main causes for this.

1) The folder the file is located in or the specific file itself has been write protected. The Windows operating system controls these permissions. Right click on the folder or file in Windows Explorer and select Properties. The object may be write protected through its Attributes or within the Security page. Make sure that the write operation is allowed. A simple way to check to see if the folder is write protected is to load a program such as Notepad and try to save a small text file to the folder. If you are able to successfully save a file, then the folder is fine, and it may be the specific file that is the issue.

2) The path that Micro-Cap is trying to write the file to does not exist. If any of the folders within the path do not exist, then the write operation will fail. For most cases, the paths that Micro-Cap uses are defined within the Paths dialog box. Go to the File menu and select Paths. In the dialog box that is invoked, check that all of the specified paths are valid. When the OK button is clicked in this dialog box, Micro-Cap will automatically check the validity of all specified paths and will return an error message specifying any invalid paths. An invalid path in this dialog box usually occurs when a Micro-Cap installation is copied directly from one system to another but its location on the hard drive is shifted to a different partition or folder.






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DC Analysis
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Initial Conditions
Monte Carlo
Schematic Editor
Transient Analysis