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Personal Computer Space Transactor 2001 (Computer Space 2001)
by Norbert Landsteiner, 2017 <www.masswerk.at>
(a project for RetroChallenge 2017/04)

Original Computer Space arcade game (c) 1971 Nutting Associates, Inc.
by Nolan Bushnell and Ted Dabney.


Version 1.1

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Instructions

While Computer Space, the very first coin-operated arcade video game,
inspite of its name, wasn't a computer program, but merely a digital
signal generator in solid-state TTL logic, we here recreate the game
in a simulation for the PET 2001 and its PETSCII graphics.

Quoting the original instructions:

             COMPUTER SPACE

    A SIMULATED BATTLE THAT PITS
    COMPUTER-GUIDED SAUCERS AGAINST
    A ROCKET SHIP THAT YOU CONTROL.

    EVADE THE SAUCER'S MISSILES AND
    USE YOURS TO SCORE HITS.

    OUTSCORE THE SAUCERS FOR EX-
    TENDED PLAY IN HYPERSPACE.



Controls

  A ............ thrust
  D (or F) ..... fire missile
  K (or J) ..... turn left
  L   .......... turn right

A missile may be controlled on its path by turning the rocket ship.


Scoring and Score Display (from top to bottom):

  Rocket (player)   1 digit (decimal or hex), any overflow ignored
  Saucer (computer) 1 digit (decimal or hex), any overflow ignored
  Time              2 digits (decimal), counting up from 1 to 99


The object of the game is to outscore the saucers for an extra play in
"hyperspace", shown in reverse video. Here's a quote from the original
game flyer by Nutting Associates, Inc.:

  "Outscore or hit the saucers with your missiles more times than
  they hit you for extended play in hyperspace. Attain hyperspace
  and the playfield turns white and gives you a vision of daylight
  in outer space. Thrill to reality of controlling your own rocket
  ship in gravity-free outer space. Battle the saucers in a duel
  of wit and coordination!"



Options

At the start of the program, scores for the rocket ship and the saucers
may be set up individually to count either in decimal or in hexadecimal
digits. Refer to the following graphics for hexadecimal digit displays:

                *  *   ****   *
                *  *   *      *
  ****   ****   ****   ****   ****    **
  *         *                 *
  ****   ****          ****   ****
  
   10     11     12     13     14     15

(Hexadecimal digits as generated by the Intel 7448 BCD-to-7-Segement decoder.
 While 15 is originally blank, it is substituted by a dash in the game.)



Compatibility

The game runs both on ROM 1.0 and ROM 2.0 and auto-configures for the
ROM version found on the specific machine. While not tested, ROM 4.0
should be fine as well. Minimum RAM: 8K (6.6K used).
(The program has been tested in emulation only.)

Version 0.9.3 adds a C64 version, see file "computerspace2001_c64.prg".
In order to assemble the program anew targeting the C64 as the system, just
uncomment the "C64 = 1" flag at the top of the source file.

The version for the C64 is identical to PET version, aside from minor
visual differences due to differences in the character ROM (missing back-
slash character and bolder font). Otherwise, version 0.9.3 is the same game
as 0.9.2 and there are no differences on the PET.



Version History

1.1      A few readjustments ...
1.0      Adjusted timing and pace, improved rocket thrust animation and
         response of rocket turn. Also, missiles now respond in a more
         direct manner to the rocket's turn.
0.9.7 - 0.9.9    Fiddling with rocket velocity adjustments.
0.9.6    Added pause function (STOP key), revised pace, rocket motion is now
         more "viscous".
0.9.5    Slowed pace of saucer motion and decreased maximum speed of the
         player's rocket ship accordingly.
0.9.4    Small fix/correction.
0.9.3    Added C64 compatibility (as an alternative assembly target).
         Reordered zeropage addresses used by the program.
0.9.2    Minor fixes & corrections.
0.9.1    First release.



License & Copying

The software is provided as-is, any warranties or claims of fitness are
disclaimed.

The program may be distributed and modified freely as long it is
accompanied by this file and the original credits (see above).

Download: http://wwww.masswerk.at/rc2017/04/release.html

Development blog: http://wwww.masswerk.at/rc2017/04/

(In case you like the game or appreciate the effort, consider a donation
in the best tradition of shareware. A PayPal button is to be found at the
download page.)


The source file is set up for the ACME cross-assembler,
https://sourceforge.net/projects/acme-crossass/
(set editor tab-stops to 16 for best display results)


Norbert Landsteiner
Vienna, June 2017
