aap_

With Multics i'm familiar enough, i meant unisys specifically.

Is it at all possible to get a peak into that world as a curious person?

Crazy to think that it's apparently acceptable to centralize the web like that.

Yup! I used to use FreeBSD on my thinkpad but as time went on that became less practical and I've been on Linux ever since. First arch and then void kinda filled the spot. void feels a bit like home.

Immutability is a central concept in functional programming.

Unfortunately I can't help with the classical picture, but in quantum physics it all comes out very nicely: You can interpret the Lagrangian as giving all possibilities to build a trajectory through spacetime. In the path integral formulation we then follow one such trajectory from one configuration to another configuration and find its amplitude. And then we integrate over all possible trajectories that we could have picked. For incoherent trajectories there will always be another one that cancels out the amplitude. Where the amplitudes add up constructively you will find stationary action and the classical behavior in the limit. So this is a depth-first approach: first follow one trajectory completely, then add up all possible trajectories.

The Hamiltonian approach in contrast is breadth-first: you single out a time axis, start with some initial state, and consider all possibilities that a particle (or field in QFT) could evolve forwards in time just a tiny bit (this is what the Hamiltonian operator does). Then you add up all these possibilities to find the next state, and so you move forwards through time by keeping track of all possible evolutions all at once. This massive superposition of everything that is possible (with corresponding amplitudes) is what you call a state (or wavefunction) and the space that it lives in is the Hilbert (or Fock) space.

So Lagrangian/path-integral: follow full trajectories, then add up all possible choices. depth-first

Hamiltonian/time-evolution: add up all choices for a tiny step in time, then simply do more steps: breadth-first

I imagine it a bit like a scanline algorithm calculating an image as it moves down the screen (Hamiltonian) vs something like a stochastic raytracer that can start with an empty image and refine it pixel by pixel by shooting more rays (Lagrangian)

This is my layman explanation anyways...hopefully it helps, even though i can't say much about their relationship in classical physics.

That's true but it was little more than a portable rendering API, which was of course very useful for the PS2, but probably less interesting for the PC ports. So if you want to count that, you're right, it's not totally from scratch. But it wasn't built on an actual game engine.

As for Rockstar North/DMA specifically: It was a bunch of nerds making games in Scotland. From having reverse engineered gta3 and vice city and therefore knowing the code of these games quite intimately, i can tell that even at that time (i don't know what exactly was meant by "early") they were still a fairly small bunch of very talented people building the best game together that they could. No huge engines or design patterns, just very straightforward, well or reasonably well written code that does just what's it supposed to. All from scratch, the tooling as well. Of course that's just my interpretation (and maybe i'm projecting a bit) but i imagine it must have been a very fun project for the people involved. Doesn't reek much of management, bureaucracy and questionable practices getting in the way.

Really cool! This is the sorta thing that, just yesterday, I wished existed. And it's already on the HN frontpage. It's hard to see the forest for the trees in many math books, a bird's eye view is a really valuable perspective.

I highly appreciate this approach: "As i have ranted about before, linear algebra is done wrong by the extensive use of matrices to obscure the structure of a linear map. Similar problems occcur with multivariable calculus, so here I would like to set the record straight"

Math education and textbooks are doing an awesome job obscuring simple ideas by focusing on weird details and bad notation. Always good to see people trying to counter this :)

That was a very approachable explanation. Makes a lot of sense. Essentially by encoding the program algebraically you can prove that it is invariant under the action of the semi-lattice. Very neat! Maybe lean is worth a look.

Session persistence is the key feature for me. All the rest I don't need because i simply open more windows. However multiple windows (or whatever you call them) were really useful when I bought a vt100 as a teenager and programmed on that for a while for fun (with screen at the time, not tmux).

Where is perl being used today? I imagine it has a diehard community, but it's not very publicly visible these days.

LISP had FEXPRs from the beginning though. Not identical to macros, but similar in spirit.

Always nice to see more B. Here's mine: https://github.com/aap/b

Parent was not talking about the origin though. Present day obsession with so called "race" is absolutely a US phenomenon. Classifying people as "caucasian" for instance always trips me up because it's something that people would call you a nazi for elsewhere.

I always joke that forth doesn't actually exist. The only forth code that seems to exist is forth implementations.

If Toki Pona has too many words for you, try Tuki Tiki, it only has 39 words.

I hadn't connected it to the pidp-10 panel yet actually, my stuff is older than that. but eventually i would like to. the approach i went with was to put some of the peripherals on the linux side of things but have the controller logic on the FPGA. it's all a bit fiddly with FPGAs...

This is a good start: https://www.masswerk.at/minskytron/

The pdp-1 "demoscene" has been rather inactive for ~6 decades now :) Our hope is to breathe some new life into it.

In case you didn't see, the hackaday project page has two more links on the side, but currently information is a bit sparse, sorry. We're currently on a sprint to finish and polish the software distribution.

I have a bunch of KA10 verilog that worked on a DE10-nano in the past, but it's been quite a while and i think i have a bunch of uncommitted stuff lying around as well. The verilog is based on the original schematics and I successfully ran LISP and Spacewar on it. Unfortunately simulating peripherals is always a pain, so the project currently lies dormant. But i'd like to pick it up again at some point. I just really need to rethink my approach how to do this, qsys was maybe not the greatest way to wire up the system.

https://github.com/aap/fpdpga/tree/master/ka10

There are some versions of MIDAS around on bitsavers but I have to admit i haven't really looked into them much yet. Gotta leave something to the community, right? (or so i tell myself...). Another thing is that not all PDP-1s were the same and especially the PDP-1/X at MIT was a super hacked up version. Any code for that will not run my emulation (at least for now).

A real tape reader would be great and is something we are considering for the future, but without a punch it's not very satisfying. There will be a paper tape visualization though (currently writing the code for that).

As one of those guys in the photo I really hope everyone will have a lot of fun with this :)

The photos don't show it but you can also have your PiDP-1 in white instead of blue. It will come with both sets of front panels.

Unfortunately we don't seem to have the MCS8080 macros to assemble this in the original way. Hopefully they will turn up eventually

No, if you need fixed addresses i suppose a linker script would be the way to go? Or in this case you'd just serialize the data such that it doesn't contain any pointers in the first place.

Anecdote probably not. But i learned how a compiler works from it and reconstructed the B compiler based on it (found here: https://github.com/aap/b, warning: repo is messy, will clean up more soon hopefully).

See my other comment.

It's an awkward way to reserve memory. The important detail here is that both compiler phases do this, and the way the programs are linked guarantees that the reserved region has the same address in both phases. Therefore an expression tree involving pointers can be passed to the second phase very succinctly. Not pretty, no, but hardware limitations force you to do come up with strange solutions sometimes.

As a german i hadn't heard of the wright brothers until my 20s. Otto Lilienthal is the name associated with the invention of airplanes here.

Probably one of my favorite pieces of software of all times. Learned so much from this!