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Xortran - A PDP-11 Neural Network With Backpropagation in Fortran IV
- deleted 11mo ago[deleted]
- jacobgorm 11mo agoWhen I studied cognitive psychology I remember one of the professors told us about how they had been playing with implementing neurals nets on their PDP11 back in the day. I remember thinking that had to have been be a total waste of time. Silly me.
- rahen 11mo agoThe first convolutional neural network, the Neocognitron, was AFAIK implemented on a PDP-11 as well: https://www.semanticscholar.org/paper/Neocognitron%3A-A-neural-network-model-for-a-of-Fukushima-Miyake/0bc161be3f413c79fd12c2538a999c3db2efb26f https://www.semanticscholar.org/paper/Neocognitron%3A-A-neur... No backpropagation back then, this only appeared around 1986 with Rumelhart, probably on VAX machines by that time. The 11/34 was hardly a powerhouse (roughly a turbo XT) but it was sturdy, could handle sustained load and its FPU made the whole difference.
- PaulHoule 11mo agoIf I remember right that FORTRAN IV compiler really sucked, it used a stack machine and that floating point accelerator "sucked" by normal standards but was actually 100% effective at accelerating that stack machine. The FORTRAN 77 compiler that came latter was better.
- rahen 11mo agoAuthor here. They call it a FORTRAN IV compiler but it uses some F66 extensions, such as proper types and functions, although it lacks some of the nicer constructs of F66 like If/Then/Else, which would have been handy. Regarding floating point, I realized the code actually works fine without an FPU, so I assume it uses soft-float. There's no switch to enable the FP11 opcodes, maybe that was in their F77 compiler. It's indeed rough and spartan, but using a 64KB optimizing compiler requiring just 8KB of memory was a refreshing change for me.
- fortran77 11mo agoYes! It took 73 years , but Fortran 77 was definitely better than Fortran IV
- ccgreg 11mo ago> it used a stack machine Do you have some reading for this? I've used that compiler but I never read the resulting assembly language.
- nxobject 11mo agoI always found it annoying that Rumelhart and McClelland named their books with the acronym “PDP” - Parallel Distributed Processing. Now I know that they were probably aware of the name collision…
- fortran77 11mo agoI did a few systems like this in the early 80s, but by then I was on a Vax and running Fortran 77. Nice to see this. It’s a good way to learn the basics without getting bogged down with modern complexities.