The Galaxy CAD System is an integrated environment for digital design and for rapid prototyping of CAD tools and other software. The system currently includes schematic capture and simulation of both low-level and high-level digital designs and is being expanded to include physical design tools. Galaxy runs on a number of 680X0 platforms, including the Apple Macintosh, HP9000/3XX, Apollo Domain, and Atari ST. Others will be added according to demand.
The Galaxy CAD System is an ideal environment for teaching digital design. It has been used successfully for both introductory logic design and computer design courses at Wisconsin. Some of the features of Galaxy that make it suitable for education are:
L 1. Integrated multiple-window environment: All Galaxy tools run concurrently in a multiple window environment. Copying data from one window to another is simple. Any number of simulation sessions can be active simultaneously. 2. Hierarchy: the schematic editor and simulator are both fully hierarchical. Building hierarchical designs is simple, including creating symbols for modules. The simulator is a true hierarchical simulator: it does not require a time-consuming macro-expansion step. 3. Integrated editing and simulation: Designs are edited and simulated in the same environment. Simulation input and output can be shown directly on schematics, allowing direct manipulation of net values. Unlike other products, Galaxy does not require modification of the schematic to insert "switch" and "light" components. In addition, Galaxy allows display of bus values in hexadecimal directly on schematics to simplify debugging of high-level designs. Simulation I/O can also use waveforms, text files, and tables. 4. Faults: Stuck-at faults can be introduced on the schematic editor and simulated immediately without rebuilding the simulation model. This provides an excellent way to display the effects of faults. 5. Buses: Galaxy supports specification and simulation of bus structures, including complex extractions, fanouts, and bit reversal. Buses are specified by annotating nets with text. For simulation, buses are kept intact so that multiple-bit high-level components can be used. Galaxy includes a library of register-transfer components suitable for high-level computer design and simulation. 6. Alternate specification of designs: In addition to schematics, Galaxy users can specify design modules using a textual HDL (GHDL) and using hardware flowcharts and state diagrams. A hierarchical design can mix these representations as desired. 7. High-quality PostScript output: Galaxy schematics are of excellent quality. Gates are drawn according to standard practices, e.g., OR gates are drawn with the correct circular arcs and not ellipses. 8. Uniform user interface: Galaxy tools have the same user interface on all platforms, reducing student learning curves. In fact, the same tool OBJECT CODE runs on all platforms due to the unique structure of Galaxy. 9. Adding new simulation primitives is straightforward. 10. No cost: Galaxy is available for free via anonymous FTP (Apple Macintosh version). Other versions will be made available based on demand.Galaxy is also an excellent environment for rapid prototyping of new CAD tools. By building on top of available resources, we have been able to prototype new tools in days or weeks that would ordinarily have taken months or years. For more information, send e-mail.
To obtain Galaxy CAD, connect to "ftp://eceserv0.ece.wisc.edu/pub/galaxy" using FTP. Log in as "anonymous" with password "guest". Galaxy is in directory "pub/galaxy". The file "README" in that directory gives further instructions. Please register as a user by sending e-mail to "email@example.com".
L John F. Beetem ECE Department University of Wisconsin - Madison Madison, WI 53706 USA (608) 262-6229 firstname.lastname@example.org
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