4 ms·

Well, I suppose that the conjunction of a lower demand and a more complex processor (which executed Lisp directly) is a good reason for them to be expensive. Th

by edu 18y ago

Well, I suppose that the conjunction of a lower demand and a more complex processor (which executed Lisp directly) is a good reason for them to be expensive. The complexity is a problem in the beginning, and if the demand had been higher the prices would lowered, but... I think the main reason of the failure was due to the business side and not the technical merits, unfortunately history shows that technological success has more to do with business skills (i.e., ms) than with the technology (i.e., Lisp Machines, 80's Apples...)

chandler 18y ago
>> (which executed Lisp directly) Uh, the machine's architectures were probably designed to be more amenable to Lisp-esque features (e.g., garbage collection, tagged types at runtime, native pair operations, etc); I suspect the machines didn't execute Lisp directly for the same reason that an x86 doesn't execute C directly...
- edu 18y ago
  Well, evidently the processors worked with binary instructions, but these were based on primitive Lisp operations. There's more information in http://hdl.handle.net/1721.1/5731 http://hdl.handle.net/1721.1/5731 and quoting from the wikipedia http://en.wikipedia.org/wiki/Lisp_machine http://en.wikipedia.org/wiki/Lisp_machine These machines had hardware support for various primitive Lisp operations (data type testing, CDR coding) and also hardware support for incremental garbage collection. They ran large Lisp programs very efficiently.
- cpr 18y ago
  The microarchitecture really implemented Lisp primitives like cons, car, cdr, array ref as opcodes, etc. That's about as close to executing Lisp directly as you can get.
  - ajross 18y ago
    That's how it's commonly explained, but it's not really correct. The bitsavers.org folks have a copy of the original Lisp Machine paper: http://www.bitsavers.org/pdf/mit/cons/TheLispMachine_Nov74.pdf http://www.bitsavers.org/pdf/mit/cons/TheLispMachine_Nov74.p... The pointer/register format was very LISP-friendly, but the actual instructions are much more conventional. The trick is that instead of having to test the tag bits with separate instructions, the "load" instruction equivalent does it in hardware.
    - cpr 18y ago
      Well, if you look on pages 13-14 of the manual you referenced, you'll find instruction codes for PCAR, PCDR, SCDR, SCDDR, NCONS, CONS, LIST (alloc), CxxxR, CxxxXR, GET, GETL, ASSQ, ASSOC, etc. Seems like Lisp primitive instructions to me.
  - jrockway 18y ago
    Keep in mind that "car" and "cdr" were opcodes stolen from processors that existed way before lisp machine :)
cpr 18y ago
Well, given that Sun workstations started running commercial Lisps at some "reasonable speed" around this time, that pretty much doomed Symbolics/LMI/TI's efforts. The cost differential between the specialized hardware (ca $100K) and the commodity workstations (ca $10-20K) was just too much. When you think about it at another level, there's not enough difference between a decent Lisp compiler producing 68K instructions for the Lisp primivites on the Sun workstation, and the microcode in the Lisp machine running micro-instructions implementing Lisp primitives. So the commodity hardware won out, as it usually does.

by edu 18y ago

chandler 18y ago

>> (which executed Lisp directly) Uh, the machine's architectures were probably designed to be more amenable to Lisp-esque features (e.g., garbage collection, tagged types at runtime, native pair operations, etc); I suspect the machines didn't execute Lisp directly for the same reason that an x86 doesn't execute C directly...

edu 18y ago
Well, evidently the processors worked with binary instructions, but these were based on primitive Lisp operations. There's more information in http://hdl.handle.net/1721.1/5731 http://hdl.handle.net/1721.1/5731 and quoting from the wikipedia http://en.wikipedia.org/wiki/Lisp_machine http://en.wikipedia.org/wiki/Lisp_machine These machines had hardware support for various primitive Lisp operations (data type testing, CDR coding) and also hardware support for incremental garbage collection. They ran large Lisp programs very efficiently.
cpr 18y ago
The microarchitecture really implemented Lisp primitives like cons, car, cdr, array ref as opcodes, etc. That's about as close to executing Lisp directly as you can get.
- ajross 18y ago
  That's how it's commonly explained, but it's not really correct. The bitsavers.org folks have a copy of the original Lisp Machine paper: http://www.bitsavers.org/pdf/mit/cons/TheLispMachine_Nov74.pdf http://www.bitsavers.org/pdf/mit/cons/TheLispMachine_Nov74.p... The pointer/register format was very LISP-friendly, but the actual instructions are much more conventional. The trick is that instead of having to test the tag bits with separate instructions, the "load" instruction equivalent does it in hardware.
  - cpr 18y ago
    Well, if you look on pages 13-14 of the manual you referenced, you'll find instruction codes for PCAR, PCDR, SCDR, SCDDR, NCONS, CONS, LIST (alloc), CxxxR, CxxxXR, GET, GETL, ASSQ, ASSOC, etc. Seems like Lisp primitive instructions to me.
- jrockway 18y ago
  Keep in mind that "car" and "cdr" were opcodes stolen from processors that existed way before lisp machine :)

cpr 18y ago

Well, given that Sun workstations started running commercial Lisps at some "reasonable speed" around this time, that pretty much doomed Symbolics/LMI/TI's efforts. The cost differential between the specialized hardware (ca $100K) and the commodity workstations (ca $10-20K) was just too much. When you think about it at another level, there's not enough difference between a decent Lisp compiler producing 68K instructions for the Lisp primivites on the Sun workstation, and the microcode in the Lisp machine running micro-instructions implementing Lisp primitives. So the commodity hardware won out, as it usually does.