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Archive-name: games/corewar-faq
Last-modified: 1992/12/04
Version: 1.7

These are the Frequently Asked Questions (and answers) from
rec.games.corewar as compiled by Mark A. Durham (durham@cup.portal.com).

Last Update: December 4, 1992

TABLE OF CONTENTS
-----------------

1. What is Core War?

2. Is it Core War or Core Wars?

3. Where can I find more information about Core War?

4. What is the ICWS?

5. What is TCWN?

6. How do I join?

7. Are back issues of TCWNs available?

8. What is the EBS?

9. Where are the Core War archives?

10. Where can I find a Core War system for . . . ?

11. I do not have ftp.  How do I get all of this great stuff?

12. I do not have access to Usenet.  How do I post and receive news?

13. When is the next tournament?

14. What is KOTH?  How do I enter?

15. Is it DAT 0, 0 or DAT #0, #0?  How do I compare to core?

16. How does SLT (Skip if Less Than) work?

17. What does (expression or term of your choice) mean?

18. Other questions?

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Q1: What is Core War?
A1: Core War is a game played by two or more programs (and vicariously
by their authors) written in an assembly language called Redcode and
run in a virtual computer called MARS (for Memory Array Redcode Simulator).
The object of the game is to cause all of the opposing programs to
terminate, leaving your program in sole possesion of the machine.

There are Core War systems available for most computer platforms.
Redcode has been standardized by the ICWS, and is therefore transportable
between all standard Core War systems.

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Q2: Is it "Core War" or "Core Wars"?
A2: Both terms are used.  Early references were to Core War.  Later
references seem to use Core Wars.  I prefer "Core War" to refer to
the game in general, "core wars" to refer to more than one specific
battle.

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Q3: Where can I find more information about Core War?
A3: Core War was first described in the "Core War Guidelines" of March,
1984 by D. G. Jones and A. K. Dewdney of the Department of Computer
Science at The University of Western Ontario (Canada).  Dewdney wrote
several "Computer Recreations" articles in "Scientific American" which
discussed Core War, starting with the May 1984 article.  Those articles
are contained in an anthology:

Author: Dewdney, A. K.
Title: The Armchair Universe: An Exploration of Computer Worlds
Published: New York: W. H. Freeman (c) 1988
ISBN: 0-7167-1939-8
Library of Congress Call Number: QA76.6 .D517 1988

(See Also Q9).

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Q4: What is the ICWS?
A4: About one year after Core War first appeared in Sci-Am, the
"International Core War Society" (ICWS) was established.  Since that
time, the ICWS has been responsible for the creation and maintenance
of Core War standards and the running of Core War tournaments.  There
have been six annual tournaments and two standards (ICWS'86 and
ICWS'88).

---------------------------------------------------------------------

Q5: What is TCWN?
A5: Since March of 1987, "The Core War Newsletter" (TCWN) has been the
official newsletter of the ICWS.  It is published quarterly and recent
issues are also available as Encapsulated PostScript on soda.berkeley.edu
(see Q9).

---------------------------------------------------------------------

Q6: How do I join?
A6: For more information about joining the ICWS (which includes a
subscription to TCWN), contact:

   Jon Newman
   13824 NE 87th Street
   Redmond, WA 98052-1959
   email: jonn@microsoft.com  (Note: Microsoft has NO affiliation with
                                     Core War.  Jon Newman just happens
                                     to work there, and we want to keep
                                     it that way!)

Current dues are $15.00 in US currency.

If you wish to contribute an article, review, cartoon, letter, joke, rumor,
etc. to TCWN, please send it to me at 

   Mark A. Durham
   18 Honeysuckle Terrace
   Spartanburg, SC 29307-3760
   email: durham@cup.portal.com

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Q7: Are back issues of TCWN available?
A7: Back issues of TCWN (up to Winter 1991) are available from

   AMRAN
   5712 Kern Drive
   Huntington Beach, CA 92649-4535

or contact William R. Buckley at xwbuckley@fullerton.edu.

Prices are unknown at this time, but should be around $5.00 (the original
cover price).

More recent issues can be found on soda.berkeley.edu (see Q9).

---------------------------------------------------------------------

Q8: What is the EBS?
A8: The Electronic Branch Section (EBS) of the ICWS is a group of
Core War enthusiasts with access to electronic mail.  There are no fees
associated with being a member of the EBS, and members do reap some of
the benefits of full ICWS membership without the expense.  For instance,
the ten best warriors submitted to the EBS tournament are entered
into the annual ICWS tournament.  All EBS business is conducted in the
rec.games.corewar newsgroup.

The current goal of the EBS is to be at the forefront of Core War by
writing and implementing new standards and test suites in preparation for
the tenth anniversary of Core War in May of 1994.  Its immediate business
will be to set up a Charter and establish its officers.  Contact me (see
Q6) if you are interested in helping serve the EBS.

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A9: Where is the Core War archive?
Q9: Many documents such as the guidelines and the ICWS standards
along with previous tournament Redcode entries and complete Core War
systems are available via anonymous ftp from soda.berkeley.edu
(128.32.131.179) in the /pub/corewar directories.  Also, most of
past rec.games.corewar postings (including Redcode source listings)
are archived there.  Jon Blow (blojo@soda.berkeley.edu) is the archive
administrator.

Much of what is available on soda is also available on the German archive
at iraun1.ira.uka.de (129.13.10.90) in the /pub/X11/corewars directory.

This FAQ is automatically archived by news.answers.  See the header for
the current archive name and news.answers for how to get it.

----------------------------------------------------------------------

Q10: Where can I find a Core War system for . . . ?
A10: Core War systems are available via anonymous ftp from
soda.berkeley.edu in the pub/corewar/systems directory.
Currently, there are Unix X-Window, IBM PC-compatible (sorry, no systems
specifically designed for MS-Windows yet), Macintosh, and Amiga
Core War systems available there.

CAUTION!  There are many, many Core War systems available which are NOT
ICWS'88 (or even ICWS'86) compatible available at various archive sites
other than soda.berkeley.edu.  Generally, the older the program - the less
likely it will be ICWS compatible.

Reviews of Core War systems would be greatly appreciated in the newsgroup
and in the newsletter.  Please post or email to me any review of any
Core War system you have tried out so that others may learn from your
experience.

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Q11: I do not have ftp.  How do I get all of this great stuff?
A11: There is an ftp email server at ftpmail@decwrl.dec.com.  Send
email with a subject and body text of "help" (without the quotes) for
more information on its usage.

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Q12: I do not have access to Usenet.  How do I post and receive news?
A12: I know of no Usenet email server at this time.  I am trying to find
a server and verify its function.  If anyone knows of one, please let me
know so I can include it in the next FAQ.

If you somehow receive rec.games.corewar but just can't post, you can
email your post to rec-games-corewar@cs.utexas.edu and it will be
automatically posted for you.

----------------------------------------------------------------------

Q13: When is the next tournament?
A13: The 1992 Annual ICWS tournament will be held December 15th, 1992.
The rules are currently ICWS'88, core size of 8192, maximum number of
processes per warrior of 8000, and ties declared after 100 000 cycles.
The format is round-robin.  Scoring is three points per win, one point per
tie, and no points for losses.

To enter you must be a member of the International Core War Society or
successfully participate in one of the Branch Section preliminary
tournaments ("successfully" meaning finish in the top five/ten [see below]).

Valid entries should be sent to Jon Newman either via email to
jonn@microsoft.com of via mail on 3.5" disk (800K Mac or 720K IBM), 5.25"
disk (720K IBM or 1.2MB IBM), or printed.  Disk entries should be in a
simple ASCII text format and on virus-free disks.

ICWS Members may submit one entry or two entries if in electronic form.
Branch Sections may submit five entries, or ten if in electronic form.
Entries are limited to 50 instructions, 300 if in electronic form.  (Blank
lines, comment lines, EQUates, etc. are not counted as instructions).  No
scatter loading will be supported (instructions must be contiguous).

All entries become public domain on submission.  The ICWS will keep them
confidential until after the tournament has been completed.

This is the final call for warriors for the 1992 tournament.

----------------------------------------------------------------------

Q14: What is KOTH?  How do I enter?
A14: King Of The Hill (KOTH) is an ongoing Core War tournament available
to anyone with email provided by William Shubert (wms@iwarp.intel.com).
You enter by submitting via email a Redcode program with special comment
lines.  You will receive a reply indicating how well your program did
against the current top twenty programs "on the hill".  If your program
finished in the top twenty, it will remain on the hill until such time as
it finishes twenty-first against another challenger, at which time it
"falls off" the hill.

Entry rules for King of the Hill Corewar:

1) Write a corewar program.  KotH is fully ICWS '88 compatible, EXCEPT that
   a comma (",") is required between two arguments.

2) Put the line ";redcode" at the top of your program.  This MUST be the
   first line.  Anything before it will be lost.  If you wish to receive
   mail on every new entrant, use ";redcode verbose".  Otherwise you will
   only receive mail if a challenger makes it onto the hill.  Use
   ";redcode quiet" if you wish to receive mail only when you get shoved
   off the hill.  (Also, see 5 below).

   Additionally, adding ";name <program name>" and ";author <your name>"
   will be helpful in the performance reports.  Do NOT have a line
   beginning with ";address" in your code; this will confuse the mail daemon
   and you won't get mail back.

   In addition, it would be nice if you have lines beginning with
   ";strategy" that describe the algorithm you use.

3) Mail this file to "wms@iwarp.intel.com".

4) Within a few minutes you should get mail back telling you whether your
   program assembled correctly or not.  If it did assemble correctly,
   sit back and wait; if not, make the change required and re-submit.

5) In an hour or so you should get more mail telling you how your program
   performed against the current top 20 programs.  If no news arrives in an
   hour, don't worry; entries are put in a queue and run through the
   tournament one at a time.  A backlog may develop.  Be patient.

   If your program makes it onto the hill, you will get mail every time a
   new program makes it onto the hill.  If this is too much mail, you can use
   ";redcode quiet" when you first mail in your program; then you will only
   get mail when you make it on the top 20 list or when you are knocked off.
   Using ";redcode verbose" will give you even more mail; here you get mail
   every time a new challenger arrives, even if they don't make it onto the
   top 20 list.

   Often programmers want to try out slight variations in their programs.
   If you already have a program named "Foo V1.0" on the hill, adding the
   line ";kill foo" to a new program will automatically bump foo 1.0 off the
   hill.  Just ";kill" will remove all of your programs when you submit the
   new one.


MORE ON KOTH COREWAR IMPLEMENTATION
       Core size: 8,000 instructions
   Max processes: 8,000 per program
        Duration: After 80,000 cycles per program a tie is declared.
Max entry length: 100 instructions

   Programs are guaranteed a 100 instruction block (inclusive of their
   warrior's instructions) without overlapping their opponent.


SAMPLE ENTRY:
;redcode
;name Dwarf
;author A. K. Dewdney
;strategy Throw DAT bombs around memory, hitting every 4th memory cell.
;strategy   This program was presented in the first Corewar article.
bomb  DAT   #0
dwarf ADD   #4,    bomb
      MOV   bomb, @bomb
      JMP   dwarf
      END   dwarf          ; Programs start at the first line unless
                           ; and "END start" appears to indicate the
                           ; first logical instruction.

Rule variants for "eXperimental" corewar:
The same as above but use ";redcode-x" to start your program.

Your program will be entered into a second tournament with slightly
different rules.  The rules are:
   - All addressing modes are allowed with all instructions.
   - There is an additional addressing mode, called "postincrement".  To use
     it try an instruction like "mov >5,6".
   - The maximum write distance is 250 instructions.  That is, every time
     your program tries to modify memory, the address is checked; if it is
     more than 250 instructions from the process doing the modify, then
     memory is left unchanged, but the instruction continues as normal.
   - A tie is not declared until 150,000 cycles per program have elapsed.

KotH runs on any Unix system with an X windows interface.  The source code
to KotH is available by email from William Shubert.  Write to him at
(wms@iwarp.intel.com) for a copy or get it by anonymous FTP from
soda.berkeley.edu in the pub/corewar/systems directory.

----------------------------------------------------------------------

Q15: Is it DAT 0, 0 or DAT #0, #0?  How do I compare to core?
A15: Core is initialized to DAT 0, 0.  This is an "illegal" instruction
under ICWS'88 rules and strictly compliant assemblers (such as KotH)
will not let you write a DAT 0, 0 instruction - only DAT #0, #0.  So
this begs the question, how to compare something to see if it is empty
core.  The answer is, most likely the instruction before your first
instruction and the instruction after your last instruction are both
DAT 0, 0.  You can use them, or any other likely unmodified instructions,
for comparison.

----------------------------------------------------------------------

Q16: How does SLT (Skip if Less Than) work?
A16: SLT gives some people trouble because of the way modular arithmetic
works.  It is important to note that all negative numbers are converted
to positive numbers before a battles begins.  Example: (-1) becomes
(M - 1) where M is the memory size.

Once you realize that all numbers are treated as positive, it is clear 
what is meant by "less than".  It should also be clear that no number is
less than zero.

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Q17: What does (expression or term of your choice) mean?
A17: Here is a selected glossary of terms.  If you have a definition and/or
term you wish to see here, please send it to me.

(References to an X-like program mean that the term X is derived from the
   specific program X and has become a generic term).

B-Scanners - Scanners which only recognize non-zero B-fields.

CMP-Scanner - A Scanner which uses a CMP instruction to look for opponents.

Color - Property of bombs which also slow down Scanners.

Decoys - Instructions meant to slow down Scanners.  Typically, DATs with
   non-zero B-fields.

Incendiary Bomb - An alternative to the SPL 0/JMP -1 bomb.  Looks like
   SPL 0, -8/MOV -1, <-1.  Creates a SPL 0 carpet ahead of itself.

Leech - A Leech-like program.  A program which enslaves another.  Usually
   accomplished by bombing with JMPs to a SPL 0 pit with an optional
   core-clear routine.

Off-axis - Scanners often search using a comparison between two locations
   of memory M/2 apart, where M is the memory size.  Off-axis scanners use
   different offsets.

Paper - A Paper-like program.  One which replicates a process many times.
   Part of the Paper (beats) Scissors (beats) Stone (beats Paper) analogy.

Replicator - Generic for Paper.  A program which makes many copies of
   itself.

Scanner - A Scanner-like program which searches through core for an
   opponent rather than bombing blindly.

Scissors - A Scissors-like program designed to beat replicators.  Part of
   the Paper-Scissors-Stone analogy.

Slaver - Generic term for Leech.  A program which enslaves another.

Stealth - Lack of visibility to an opponent's program.  Making B-fields
   zero to avoid B-scanners.

Stone - A Stone-like program designed to be a small bomber.  Part of the
   Paper-Scissors-Stone analogy.

Vampire - A slaver.  A program designed to sap cycles away from an opponent
   and put them toward its own uses.

----------------------------------------------------------------------

Q18: Other questions?
A18: Just ask.  Either ask in the rec.games.corewar newsgroup or send your
question(s) to me at durham@cup.portal.com.  I will do my best to answer
your question(s) or put you in touch with someone who can.  If your shy,
check out the Core War archives on soda first to see if your question
has been answered before (see Q9).

Mark A. Durham
MAD