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\\        VCCC 2021 ENTRY           \\
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Author:               Devoid
                  Break Shit Labs
                    (@BSLabs6)
System:           Commodore 64
                    + H.E.S. Forth cart
Language:         H.E.S Forth v1.2
                    (64FORTH 1.2)
Length:           30 lines (503 bytes)
                  w/ comments and spacing
Exec. Size:       2292 bytes (10 blks)


Filez:
   file_id.diz - you're reading it
   tree.d64 - D64 1541 disk image
   tree.png - screenie in PNG fmt
   tree.koa - screenie in Koala fmt
   listing.txt - ASCII code listing
   
Missing:
  I did not include the CRT ROM for HES
  Forth for IP reasons. FWIW, I do own
  this cartridge.


Instructions:
  This entry is written in Forth for the
  Commodore 64, and as such requires
  additional hardware in the form of the
  HES Forth cartridge. The ROM is fairly
  available as a CCS64 CRT image. The
  entry itself is provided as a d64 disk
  image due to the way HES Forth handles
  memory. For, e.g., the VICE emulator,
  the cmdline would be something like:
  
  x64 -cartcrt 64FORTH.crt -8 tree.d64

  assuming you have your system ROMs and
  what-not configured already, and your
  Forth cartridge is named "64FORTH.crt"

  Once booted, the entry can be run via:

    DISK DLOAD TREE<CR>
    TREE<CR>

  Viewing the source is a bit more
  involved, but with the same disk in
  unit 8:

    FILE VCCC2021<CR>

  Which will attach the page file
  containing the source. The source
  occupies two screens, which can be
  listed like:

    1 LIST<CR>

  or

    2 LIST<CR>

  If anyone needs to verify that the
  code listed is the same as the code
  executed, the two screens can be
  compiled like:

    1 LOAD<CR>
    2 LOAD<CR>

  which will re-compile the LIMB,
  SECTION, BSECT, and TREE words. The
  VCCC2021 page file must be attached
  first ("FILE VCCC2021<CR>" as above).

  Probably best to find me on Twitter
  with any questions - I don't tend to
  check emails.
  

The How:

  It's pretty straightforward Forth
  code. The only part that even
  approaches fancy is the BSECT word
  which just builds a list of "branch"
  widths on the stack given a start,
  stop, and step. HES Forth provides
  words for things like setting screen,
  border, and character colors - but the
  addresses and PETSCII codes for that
  kind of thing are burned into my brain
  even after all these years, so I just
  used those rather than figuring out
  the built-ins.

  The TREE word sets up the screen and
  calls the BSECT word once for each
  "section" of the tree/trunk. BSECT
  loads the width values onto the stack,
  then TREE calls SECTION which pulls
  those values off the stack and uses
  LIMB to draw lines of the given width
  to the display (centered). The bit of
  coloring happens in TREE.

Note:
  I decidedly went the obscure route for
  this challenge. The HES Forth cart.
  was one of the very first carts. I
  ever owned for the C=64, and the first
  language I learned that wasn't BASIC
  or 6502 assembly. I fully expect
  no-one will bother putting together
  the pieces required to run this, but
  it was super fun and nostalgic. Human
  Engineered Software and T.J. Zimmer
  did a fantastic job implementing Forth
  on this platform - I don't think I
  really appreciated that when I was
  younger. Anyway, thanks for the
  challenge!

   Sub-Note: It took me longer to write
   the Python script that pulled the
   source code out of the REL file that
   HES Forth uses as page storage than
   it did to code the entry :D But I
   felt like being pedantic.

  Gr33tZ tw0 t3h p33p13z!
  ((( RIP Ziltron 2019 ))
  
Devoid - BSL
-=EOF=-