Xortran - A PDP-11 Neural Network With Backpropagation in Fortran IV(github.com)
github.com
Xortran - A PDP-11 Neural Network With Backpropagation in Fortran IV
https://github.com/dbrll/Xortran
12 comments
When 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.
The first convolutional neural network, the Neocognitron, was AFAIK implemented on a PDP-11 as well: 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.
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.
If 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.
Author 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.
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.
Yes! It took 73 years , but Fortran 77 was definitely better than Fortran IV
Why 73 years?
Fortan IV -- released in 1904. Fortran 77: 1977
> 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.
Do you have some reading for this? I've used that compiler but I never read the resulting assembly language.
I 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…
I 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.
Nice to see this. It’s a good way to learn the basics without getting bogged down with modern complexities.
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