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.
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•2mo ago
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.
rahen•2mo ago
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.
fortran77•2mo ago
Yes! It took 73 years , but Fortran 77 was definitely better than Fortran IV
Do you have some reading for this? I've used that compiler but I never read the resulting assembly language.
nxobject•2mo ago
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…
fortran77•2mo ago
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.
jacobgorm•2mo ago
rahen•2mo ago
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•2mo ago
rahen•2mo ago
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•2mo ago
iberator•2mo ago
fortran77•2mo ago
PaulHoule•2mo ago
ccgreg•2mo ago
Do you have some reading for this? I've used that compiler but I never read the resulting assembly language.
nxobject•2mo ago