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The Apple II Source Code for the LOGO Language Found

posted by martyb on Sunday October 07 2018, @01:14PM   Printer-friendly
from the have-you-ever-programmed-a-6502? dept.

Arthur T Knackerbracket has found the following story:

Adafruit visited the history of the LOGO "turtle graphics" language not long ago.

Now on Twitter, folks have found the source code for the LOGO program used on Apple II computers. Source on GitHub.

It turns out that the program was written on a DEC PDP-10 minicomputer running the Incompatible Timesharing System (ITS).

I'd take it that the code is in 6502 assembly and the program works the whole Apple II memory map for functionality. Did ITS have a 6502 cross-compiler or did the MIDAS program have separate target environments?

Very interesting programming archaeology – see the source code yourself along with the full PDP-10 ITS image still maintained today.

-- submitted from IRC

Original Submission

 
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  • (Score: 0) by Anonymous Coward on Monday October 08 2018, @12:16AM

    by Anonymous Coward on Monday October 08 2018, @12:16AM (#745725)

    In the late-70s I worked briefly on the Terrapin Turtle, a "robot" peripheral that connected to Apple II by a cable and could draw with a pen (like a plotter -- pen_down and pen_up commands) on any surface that would accept the ink. Along the way I got to know many people in the Logo community, which was the brainchild of Seymour Papert and others at MIT.

    As well as the programming language, this community also did educational experimentation in a variety of different schools (low and high income areas, for example). They were very successful in getting elementary kids to program, sometimes working collaboratively--YouTube has videos, very inspirational watching kids solve programming problems. Many of these folks are still around, wouldn't surprise me at all if several people hung onto copies of the source.

    While I don't know the exact details, the reason to use the PDP-10 at the MIT AI Lab, which ran ITS (Incompatible Time Sharing) was almost certainly this: ITS was written by some of the best hackers, for their own use and it was by far the best/fastest software development environment of its era. This is where RMS hung out while he was an undergrad at Harvard, there is a good section on the AI Lab in https://archive.org/details/faif-2.0/page/n0 [archive.org] (this link was posted here on SN recently, I'm having fun (re)reading this updated version).

    Since Logo is effectively interpreted Lisp (with different syntax), and since the PDP-10 had excellent Lisp support (all written in-house, before commercialization by Symbolics and Lisp Machine Inc), it probably wasn't all that hard.

    As well as various different versions of Logo for the Apple II, and the Turtle robot peripheral, there was also a memory card produced that doubled the available memory for use with larger Logo programs--adding 64K bytes to the 64K in a maxed out Apple II. I had one and it came with instructions for how to use the extra memory with other software as well, although I don't think there was much support. There was also Logo for other home computers c.1980, for sure it was ported to TI and Atari computers.

    Logo short history - http://el.media.mit.edu/logo-foundation/what_is_logo/history.html [mit.edu]
    Page has links to other sections on the language and the educational activities as well.