Ask HN: What Were the Differences Between Symbolics Genera and Xerox Interlisp-D
There are a bunch of reasons. But the three main reasons:<p>* the Xerox Lisp Machines were limited: very small address space, slow, expensive. Most projects very early on reached the limits of these machines. A Symbolics would be even more expensive, but they could be enhanced with more memory. When I got to see a local, closing, lab which formerly used a bunch of Interlisp-D machines, they had a Symbolics 3600 (the first machine designed by Symbolics, followed by two more machine generations), where they tried to port the software to, since they had so much more memory space - which was needed for complex natural language software.<p>* Xerox pulled earlier out of the Lisp Machine market and did not invest more money. TI and Symbolics developed a Lisp microprocessor. Xerox did not. 1986 Xerox was talking about it, but then it was mostly dead and nothing happened. The software was offloaded to some other company and an emulator on SUN and Windows machines was offered&amp;maintained (Medley). Some projects inside Xerox PARC used Common Lisp (on workstations), for example Xerox PARC worked on CLOS and the Meta-Object Protocol for it, the Common Lisp Object System + MOP. There was a 3d UI group which developed 3d visualizations using Common Lisp on SGIs - I think with Allegro CL from Franz. Medley had a Common Lisp implementation integrated with Interlisp, but I&#x27;ve never heard about anyone using it.<p>Symbolics followed a few years later: the Ivory microprocessor was the last generation and early 90s saw then a port of Genera to the DEC ALPHA running UNIX: Open Genera.<p>* Interlisp was very different from Common Lisp, as a language - Common Lisp was the new standard pushed by the customer(s).<p>Summary: The hardware already was dead end, so was the Lisp dialect they used. Xerox was no longer interested in investing into it.<p>The difference was night and day. There was some great software developed on Interlisp-D (like LOOPS or KL-ONE), but there was no way one could develop something like the Symbolics Graphics Suite on it (with 3d modelling and animation), attach HDTV frame grabbers to it (like NASA did for Space Shuttle launch monitoring), software like iCAD was originally developed on it (which was used in Aerospace to construct planes, turbines, ...). There were a bunch of interesting customer projects. I got a used 3640, which was used by Philips medical research, got used MacIvories, which were used in scheduling the operations of a large power plant, ...<p>Positive: Interlisp now can be used again, due to open sourcing it and a project that provides improvements.<p>Btw, if we are talking about the Connection Machine from Thinking Machines, the CM1 and CM2 were co-processors to a Symbolics Lisp Machine. Thinking Machines developed a board for them, which then was the interface to the massive parallel SIMD machine, with its famous cube design. The programming was done on the Symbolics: in CM-Lisp or *Lisp, which was an extension the Common Lisp dialect on the Symbolics. *Lisp runs on the frontend (the Lisp Machine) and runs the parallel code on the Connection Machine (with up to 65536 small cores). The Connection Machine itself was not a Lisp Machine, it did not run Lisp.