International Character Sets

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SIMetrix schematic editor, waveform viewer and text editors support international character sets. This means that any language can be displayed in these tools. This section describes some of the issues with regard to International character support.

Character Encoding

The choice of character encoding scheme affects how international character sets are stored and displayed. The simplest encoding scheme is ASCII but this only supports a total of 95 printable characters. This is not adequate for displaying anything other than English text.

Older versions of SIMetrix used code page based encoding which required a language selection to be made at the system level. For example, a Japanese user would select the Japanese code page and would then be able to display Japanese characters in schematics and the like. While this worked reasonably well, a schematic drawn by a Japanese user would not display correctly in a system setup for a user whose native language is not Japanese.

Code page based encoding has been superseded by the UNICODE character encoding scheme. UNICODE is a scheme that supports all character sets worldwide and does not require the setting up of system-level code pages. There are a number of variants of UNICODE distinguished by the method of encoding its approximately 1 million characters to byte sequences. By far the most widely used is UTF-8.

UTF-8 uses 8 bit character encoding and is compatible with ASCII, that is, ASCII is a subset of UTF-8. A text file containing pure ASCII characters is also a valid UTF-8 file.

SIMetrix Character Encoding

SIMetrix version 8 and later uses UTF-8 for schematics, graphs, text editors and a few other things. This means that you can enter text in any language in a schematic and be sure that it will be displayed correctly on any system without needing a code page to be setup.

Compatibility with Older Versions

As noted previously, older versions of SIMetrix (version 7.2 and earlier) used code page based encoding and therefore are not compatible with UTF-8. However, we have developed some level of compatibility to allow interoperability between old and new versions. Note the following:

1. Schematic and graph files created with older versions will render international character sets correctly provided the system is setup with the correct code page. For example, if a schematic displayed correctly in version 7.2, it will display correctly in version 8 and later provided it is opened on the same system or a system with the same code page set up.
2. Version 7.2m or later have some UTF-8 support allowing schematics created with version 8 to display correctly in version 7.2. You must update to the most recent version of 7.2 to use this feature.

Text Editors

SIMetrix text editors will detect non-UTF-8 characters in a file and attempt to interpret them correctly. By default, the text editors will assume that the file is encoded using the local code-page. You can change this using the SetDefaultEncoding command. Refer to the Script Reference Manual for further information.