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153 lines
4.3 KiB
Plaintext
153 lines
4.3 KiB
Plaintext
Taito's Space Invaders
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## The Invaders march ...
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#### Bom bom bom bom ...
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###### Left, right, fire!
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## ## ## Faster, faster they march ...
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######## Suddenly you're 11 again!
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# # Dodge the bombs ...
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# ## # They're turning green ...
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# # # # Get them before they land!
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A version of Taito's original Space Invaders(TM) for the PC
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anarky, April 2005
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http://www.anarky.tk/
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anarkynet@hotmail.com
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Disclaimer
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This game is mailware. That is, it's free to use and distribute anywhere you
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like, but only on condition that you keep the two files together and that you
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don't charge any payment for it. Also, when you download it, email me on the
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above address.
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Also, I cannot be held responsible if this program does anything nasty to your
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machine. It hasn't damaged anyone's PC that I'm aware of and there's no reason
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why it should, really.
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Playing
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Start QuickBasic and load invader1.bas. Now press F5.
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Left - Left CTRL
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Right - Left ALT
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Fire - Right SHIFT
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Stop program - Esc
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History
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What's to be said? I remember as a kid playing the original on the big consoles.
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So I thought, "Why not port it to the PC?" Heh, so I did.
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Needs
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Basically, don't worry - it'll almost certainly work on your PC.
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Requires:
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---------
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DOS - tested with MS-DOS 7.1 and Windows 95. No known lower limit. I don't
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know if it works with Windows 2000 or Windows ME.
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VGA - tested with generic standard low-grade video card. It uses screen 13:
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320x200x256, so it should work on yours no matter what it is.
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Supports:
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---------
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Soundblaster - tested with AWE32. Make sure you've got your soundcard driver
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set up for DOS (e.g. if you have a Soundblaster, a line starting 'SET BLASTER=' in your
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c:\autoexec.bat file).
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Technical
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Uses ports:
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-----------
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&H3DA - for vertical retrace
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&H388
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&H389 - for Adlib sound
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&H3C6
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&H3C8
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&H3C9 - for palette setting
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Uses memory locations:
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----------------------
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&H417 - to read the keyboard
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Machine speed requirements:
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---------------------------
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Should run at full speed on any x86 processor.
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When interpreted, rather than compiled, the program does all its work
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within 15% of the vertical retrace cycle on a 486DX/66. The compiled
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version should keep up with the vertical retrace on an 8086.
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If you press the '=' key, the game will display how much of the vertical
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retrace time the game takes up each cycle. Exciting, eh?
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Unknown requirements:
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---------------------
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Base memory - tested with 479K free base memory
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Memory manager - tested with himem.sys and emm386.exe
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Notes
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1. The program does not attempt to detect a soundcard; it assumes a
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Soundblaster is installed. Apparently it works ok on machines without a
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soundcard, but I can't guarantee it'll work on yours.
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2. The player's bullet fire and explosion sound effects are pretty
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dismal. But so were the original sound effects.
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3. The demo mode is none. I might add one in future.
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4. The program simulates a monitor 256 pixels wide, as per the original (I
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think). The background colour for this is set to a dark grey to attempt to
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simulate a little bit of monitor wear and burn-in. I found the jet black of a
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modern PC monitor was not quite authentic enough :-) If you cannot see the
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grey background, try increasing your brightness and contrast controls.
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5. There's no high-score table, because the original game didn't have one.
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6. You can't re-assign the keys and it doesn't work with a joystick, sorry.
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7. Quake it ain't. It's just a nostalgia trip.
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Source Notes
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The file invader1.bas is the source code for the game. It's for QBASIC and it
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compiles with QuickBasic 4.5. It runs, interpreted, within QBASIC easily at
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full speed on a 486/66, probably on lower-powered machines, too.
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The code is reasonably structured. I tend to suffix variables with "s"
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to mean "status", so the variable 'saucers' means 'saucer status'.
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The SUBs and FUNCTIONs that start with "sb", e.g. "sbreset" are general-
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purpose SoundBlaster routines that can be plugged into any program
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without modification.
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What else? Well, not much - it's a very simple program. Hope you find
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it useful, though, if you're into this sort of thing!
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History
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v1 - Feb 2002
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---------------
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Version 1.0 ;) |