Big-Shell provided AutoDesk's AutoCAD with a bigger DOS Shell to use to run shell applications. It did this by rolling AutoCAD to disk when a CAD user shelled out to run an application.
When AutoCAD adopted a 386-extended protected mode code format, the amount of shell space was severely limited, preventing many applications that CAD users had become reliant on from running.
At the time of its original release, it was rather ground breaking, and quickly became a best seller for Spectrum Research.
Big Shell was written in 8088 Assembler (ASM) and C. Take a look at the original Big-Shell source code by clicking here.
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