OASIS (Open Artwork System Interchange Standard)
Open Artwork System Interchange Standard (OASIS) is a specification for hierarchical integrated circuit mask layout data format for interchange between EDA (Electronic Design Automation) software, IC mask writing tools and mask inspection tools. The name is the trademark of SEMI. It is developed by SEMI for microelectronics/fabrication industry as a replacement for GDSII format, the IC industry de facto standard for IC layout data exchange for more than three decades. Like GDSII, OASIS is a hardware- and software-independent binary data format. Its improvements is a smaller file size over GDSII file format. The smaller file sizes may result in faster loading of OASIS files. However, due to its internal structure, increased processor capacity is needed to parse these files and that can nullify performance gains conferred by smaller file size. The OASIS file format is not as common as the GDSII file format.
Handling of OASIS in the LayoutEditor
The OASIS files can be opened and saved with the normal file features. The OASIS file format stores a layer number to each element like polygon, path, etc. By default the LayoutEditor keeps these number untouched. Optional it is possible to setup a layer mapping. With this mapping a combination of layer/datatype in the OASIS file can be mapped to a layernumber in the LayoutEditor. Optional the OASIS file format has the ability to save the layernames. If the layernames are present the LayoutEditor will adjust the layer setting during loading of the OASIS file. There are some OASIS releated option in the LayoutEditor. All options can be adjusted in the SetupDialog. These options are available:
Option: use Ctrapezoids
If this option is enabled it is checked before a polygon is written, if it is a Ctrapezoid. If it is, it will be saved as a Ctrapezoid record which will need less disk memory than a polygon. Ctrapezoid will need marginally more computing time to handel. This option is enabled by default. Disable it when you have tools not supporting the Ctrapezoid records or when you never have Ctrapezoids in your design to improve performance.
Option: use Trapezoids
This option is similar to the Ctrapezoid option for normal Trapezoids. It is as well enabled by default.
Option: use compressed blocks
If this option is enabled a compression algorithm is used to compress the files more. Compressed OASIS file are not always supported by other CAD software. So the option is disabled by default.
Option: save regular polygon with more than 8 points as circle
The OASIS file format allows to handle circles. Circles are not a basic element inside the LayoutEditor and not supported by GDSII. Circle are stored as regular polygons instead. By activating this option any regular polygon with more than 8 points will be saved as a circle element and not as a polygon.
Option: map layer on open/save
If activated the layer mapping set in the LayerManager is used. Layer and layer/datatype combinations can be stored on different layers. By default this option is disabled.
Option: only save enabled layers
If enabled, shapes on disabled layers are ignored and not stored during a OASIS save. (introduced with version 20120824)