$! ------------------ CUT HERE -----------------------
$ v='f$verify(f$trnlnm("SHARE_VERIFY"))'
$!
$! This archive created by VMS_SHARE Version 7.2-007  22-FEB-1990
$!   On 30-MAY-1992 03:19:32.98   By user MASLIB 
$!
$! This VMS_SHARE Written by:
$!    Andy Harper, Kings College London UK
$!
$! Acknowledgements to:
$!    James Gray       - Original VMS_SHARE
$!    Michael Bednarek - Original Concept and implementation
$!
$!+ THIS PACKAGE DISTRIBUTED IN 2 PARTS, TO KEEP EACH PART
$!  BELOW 30 BLOCKS
$!
$! TO UNPACK THIS SHARE FILE, CONCATENATE ALL PARTS IN ORDER
$! AND EXECUTE AS A COMMAND PROCEDURE  (  @name  )
$!
$! THE FOLLOWING FILE(S) WILL BE CREATED AFTER UNPACKING:
$!       1. BUILD.COM;1
$!       2. DEFENDER.PAS;1
$!       3. DEFENDER.PIC;1
$!
$set="set"
$set symbol/scope=(nolocal,noglobal)
$f=f$parse("SHARE_TEMP","SYS$SCRATCH:.TMP_"+f$getjpi("","PID"))
$e="write sys$error  ""%UNPACK"", "
$w="write sys$output ""%UNPACK"", "
$ if f$trnlnm("SHARE_LOG") then $ w = "!"
$ ve=f$getsyi("version")
$ if ve-f$extract(0,1,ve) .ges. "4.4" then $ goto START
$ e "-E-OLDVER, Must run at least VMS 4.4"
$ v=f$verify(v)
$ exit 44
$UNPACK: SUBROUTINE ! P1=filename, P2=checksum
$ if f$search(P1) .eqs. "" then $ goto file_absent
$ e "-W-EXISTS, File ''P1' exists. Skipped."
$ delete 'f'*
$ exit
$file_absent:
$ if f$parse(P1) .nes. "" then $ goto dirok
$ dn=f$parse(P1,,,"DIRECTORY")
$ w "-I-CREDIR, Creating directory ''dn'."
$ create/dir 'dn'
$ if $status then $ goto dirok
$ e "-E-CREDIRFAIL, Unable to create ''dn'. File skipped."
$ delete 'f'*
$ exit
$dirok:
$ w "-I-PROCESS, Processing file ''P1'."
$ if .not. f$verify() then $ define/user sys$output nl:
$ EDIT/TPU/NOSEC/NODIS/COM=SYS$INPUT 'f'/OUT='P1'
PROCEDURE Unpacker ON_ERROR ENDON_ERROR;SET(FACILITY_NAME,"UNPACK");SET(
SUCCESS,OFF);SET(INFORMATIONAL,OFF);f:=GET_INFO(COMMAND_LINE,"file_name");b:=
CREATE_BUFFER(f,f);p:=SPAN(" ")@r&LINE_END;POSITION(BEGINNING_OF(b));
LOOP EXITIF SEARCH(p,FORWARD)=0;POSITION(r);ERASE(r);ENDLOOP;POSITION(
BEGINNING_OF(b));g:=0;LOOP EXITIF MARK(NONE)=END_OF(b);x:=ERASE_CHARACTER(1);
IF g=0 THEN IF x="X" THEN MOVE_VERTICAL(1);ENDIF;IF x="V" THEN APPEND_LINE;
MOVE_HORIZONTAL(-CURRENT_OFFSET);MOVE_VERTICAL(1);ENDIF;IF x="+" THEN g:=1;
ERASE_LINE;ENDIF;ELSE IF x="-" THEN IF INDEX(CURRENT_LINE,"+-+-+-+-+-+-+-+")=
1 THEN g:=0;ENDIF;ENDIF;ERASE_LINE;ENDIF;ENDLOOP;t:="0123456789ABCDEF";
POSITION(BEGINNING_OF(b));LOOP r:=SEARCH("`",FORWARD);EXITIF r=0;POSITION(r);
ERASE(r);x1:=INDEX(t,ERASE_CHARACTER(1))-1;x2:=INDEX(t,ERASE_CHARACTER(1))-1;
COPY_TEXT(ASCII(16*x1+x2));ENDLOOP;WRITE_FILE(b,GET_INFO(COMMAND_LINE,
"output_file"));ENDPROCEDURE;Unpacker;QUIT;
$ delete/nolog 'f'*
$ CHECKSUM 'P1'
$ IF CHECKSUM$CHECKSUM .eqs. P2 THEN $ EXIT
$ e "-E-CHKSMFAIL, Checksum of ''P1' failed."
$ ENDSUBROUTINE
$START:
$ create 'f'
X$ PASCAL DEFENDER
X$ LINK DEFENDER, INTERACT/LIB
X$ DELETE *.OBJ;*/NOCONFIRM
X$ EXIT
$ CALL UNPACK BUILD.COM;1 140579402
$ create 'f'
X`5B
X  Inherit`20
X    (
X      'SYS$LIBRARY:STARLET',
X      'INTERACT'
X    )
X`5D
X
XPROGRAM  Defender;
X
XCONST
X  max_aliens = 8;
XTYPE
X  pointer = `5Eshot;
X  shot    = record
X              x_posn : integer;
X              y_posn : integer;
X              prev   : pointer;
X              next   : pointer;
X            End;
X  v_array = varying `5B200`5D of char;
XVAR
X  Screen        : array `5B1..40,1..20`5D of integer;
X  x_alien       : array `5B1..max_aliens`5D of integer;
X  y_alien       : array `5B1..max_aliens`5D of integer;
X  d_alien       : array `5B1..max_aliens`5D of integer;
X  alien_type    : array `5B1..max_aliens`5D of char;
X  alien_alive   : array `5B1..max_aliens`5D of boolean;
X  gun_working   : array `5B1..9`5D of boolean;
X  gun_shot      : array `5B1..9`5D of integer;
X  score         : integer;
X  penality      : integer;
X  command       : char;
X  head_shot     : pointer;
X  this_shot     : pointer;
X  shot_deleted  : boolean;
X
X
XPROCEDURE  Setup;
XVAR
X  i : integer;
X  x : integer;
X  y : integer;
XBEGIN
X  command := ' ';
X  clear;
X  qio_write (VT100_inverse);
X  FOR y := 1 to 24 do
X    BEGIN
X      posn (1,y);
X      qio_write (VT100_wide);
X    END;
X  FOR y := 21 to 22 do
X    BEGIN
X      posn (1,y);
X      FOR x := 1 to 40 do
X        qio_write (' ');
X    END;
X
X  FOR i := 1 to max_aliens do
X    alien_alive`5Bi`5D := false;
X
X  FOR i := 1 to 9 do
X    gun_working`5Bi`5D := true;
X
X  qio_write (VT100_normal);
X
X  FOR x := 1 to 9 do
X    BEGIN
X      posn (x*4,21);
X      qio_write ('`5E');
X      posn (x*4,23);
X      qio_write (dec(x));
X    END;
X
X  posn (15,24);
X  qio_write ('SCORE : 0');
XEND;
X
X
XPROCEDURE Refresh_screen;
XVAR
X  i : integer;
X  x : integer;
X  y : integer;
XBEGIN
X  command := ' ';
X  clear;
X  qio_write (VT100_inverse);
X  FOR y := 1 to 24 do
X    BEGIN
X      posn (1,y);
X      qio_write (VT100_wide);
X    END;
X  FOR y := 21 to 22 do
X    BEGIN
X      posn (1,y);
X      FOR x := 1 to 40 do
X        qio_write (' ');
X    END;
X
X  qio_write (VT100_normal);
X
X  FOR x := 1 to 9 do
X    BEGIN
X      posn (x*4,21);
X      IF gun_working`5Bx`5D then
X        qio_write ('`5E')
X      ELSE
X        qio_write ('*');
X      posn (x*4,23);
X      qio_write (dec(x));
X    END;
X
X  posn (15,24);
X  qio_write ('SCORE : 0');
XEND;
X
X
XPROCEDURE  Start_screen;
XBEGIN
X  clear;
X  show_graphedt ('Defender.pic');
XEND;
X
X
XPROCEDURE  Initialize;
XBEGIN
X  image_dir;
X  score := 1;
XEND;
X
X
XPROCEDURE  Get_command;
XVAR
X  valid_com : boolean;
X  input_buffer : v_array;
X  i : integer;
XBEGIN
X  input_buffer := qio_readln (80);
X  i := 1;
X  REPEAT
X    IF ( i > length(input_buffer) ) then
X      command := ' '
X    ELSE
X      command := input_buffer`5Bi`5D;
X    i := i + 1;
X
X    valid_com := true;
X    IF ( command in `5B'1'..'9'`5D ) then
X      IF not ( gun_working`5Bord(command)-ord('0')`5D ) or
X             ( gun_shot`5Bord(command)-ord('0')`5D = 2 ) then
X        valid_com := false;
X  UNTIL ( valid_com );
X
X  IF upper_case(command) = 'W' then
X    refresh_screen;
XEND;
X
X
XPROCEDURE  Create_aliens;
XVAR
X  but_not_for_long : integer;
X  super : integer;
X  nu : integer;
X  n : integer;
XBEGIN
X  nu := ( score div 50 ) + 1;
X  IF ( nu > max_aliens ) then
X    nu := max_aliens;
X  IF ( nu > 0 ) then
X    BEGIN
X      n := 1;
X      WHILE ( n < nu ) and ( alien_alive`5Bn`5D ) do
X        n := n + 1;
X      IF not ( alien_alive`5Bn`5D ) then
X        BEGIN
X          super := random(4);
X          IF ( super = 1 ) then
X            BEGIN
X              alien_alive`5Bn`5D := true;
X              reset_randomizer;
X              REPEAT
X                but_not_for_long := randomize(9);
X              UNTIL ( gun_working`5Bbut_not_for_long`5D );
X              CASE but_not_for_long of
X                1 : x_alien`5Bn`5D := 24;
X                2 : x_alien`5Bn`5D := 28;
X                3 : x_alien`5Bn`5D := 32;
X                4 : x_alien`5Bn`5D := 36;
X                5 : x_alien`5Bn`5D := 40;
X                6 : x_alien`5Bn`5D := 4;
X                7 : x_alien`5Bn`5D := 8;
X                8 : x_alien`5Bn`5D := 12;
X                9 : x_alien`5Bn`5D := 16;
X              END;
X              IF ( but_not_for_long > 5 ) then
X                d_alien`5Bn`5D := 1
X              ELSE
X                d_alien`5Bn`5D := -1;
X              y_alien`5Bn`5D := 1;
X              alien_type`5Bn`5D := '$';
X            END
X          ELSE
X            BEGIN
X              alien_alive`5Bn`5D := true;
X              d_alien`5Bn`5D := random(2);
X              IF ( d_alien`5Bn`5D <> 1 ) then
X                d_alien`5Bn`5D := -1;
X              x_alien`5Bn`5D := random (30)+5;
X              y_alien`5Bn`5D := 1;
X              alien_type`5Bn`5D := '#';
X            END;
X          posn (x_alien`5Bn`5D,Y_alien`5Bn`5D);
X          qio_write (alien_type`5Bn`5D);
X        END;
X    END;
XEND;
X
X
XPROCEDURE  Create_shot;
XBEGIN
X  penality := penality + 1;
X  new (this_shot);
X  this_shot`5E.next := head_shot;
X  IF ( head_shot <> nil ) then
X    head_shot`5E.prev := this_shot;
X  this_shot`5E.prev := nil;
X  head_shot := this_shot;
X  WITH this_shot`5E do
X    BEGIN
X      x_posn := (4*(ord(command)-ord('0')));
X      y_posn := 20;
X    END;
X  gun_shot`5Bord(command)-ord('0')`5D := gun_shot`5Bord(command)-ord('0')`5D
V + 1;
XEND;
X
X
XPROCEDURE  Delete_shot;
XVAR
X  temp : pointer;
XBEGIN
X  gun_shot`5Bthis_shot`5E.x_posn div 4`5D :=
X          gun_shot`5Bthis_shot`5E.x_posn div 4`5D - 1;
X  IF ( this_shot`5E.prev <> nil ) then
X    this_shot`5E.prev`5E.next := this_shot`5E.next
X  ELSE
X    head_shot := this_shot`5E.next;
X  IF ( this_shot`5E.next <> nil ) then
X    this_shot`5E.next`5E.prev := this_shot`5E.prev;
X  temp := this_shot`5E.next;
X  dispose (this_shot);
X  this_shot := temp;
X  shot_deleted := true;
XEND;
X
X
XPROCEDURE  Boom ( n : integer );
XVAR
X  i : integer;
XBEGIN
X  posn (x_alien`5Bn`5D-2,y_alien`5Bn`5D-2);
X  qio_write ('. .  ');
X  posn (x_alien`5Bn`5D-2,y_alien`5Bn`5D-1);
X  qio_write (' .  .');
X  posn (x_alien`5Bn`5D-2,y_alien`5Bn`5D);
X  qio_write ('   . ');
X  posn (x_alien`5Bn`5D-2,y_alien`5Bn`5D+1);
X  qio_write (' .   ');
X  posn (x_alien`5Bn`5D-2,y_alien`5Bn`5D+2);
X  IF ( y_alien`5Bn`5D+2 < 21 ) then
X    qio_write ('. .  ');
X  FOR i := -2 to 1 do
X    BEGIN
X      posn (x_alien`5Bn`5D-2,y_alien`5Bn`5D+i);
X      qio_write ('     ');
X    END;
X  posn (x_alien`5Bn`5D-2,y_alien`5Bn`5D+2);
X  IF ( y_alien`5Bn`5D+2 < 21 ) then
X    qio_write ('     ');
X
X`7B fix one gun `7D
X
X  reset_randomizer;
X  REPEAT
X    i := randomize(9);
X  UNTIL ( i = 0 ) or_else ( not gun_working`5Bi`5D );
X
X  IF ( i > 0 ) then
X    BEGIN
X      gun_working`5Bi`5D := true;
X      posn (i*4,21);
X      qio_write ('`5E');
X    END;
XEND;
X
X
XPROCEDURE  Move;
XVAR
X  n : integer;
X  out : v_array;
XBEGIN
X  IF ( command in `5B'1'..'9'`5D ) then
X    create_shot;
X
X`7B delete shots `7D
X  out := '';
X  this_shot := head_shot;
X  WHILE ( this_shot <> nil ) do
X    BEGIN
X      out := out + get_posn (this_shot`5E.x_posn,this_shot`5E.y_posn) + ' ';
X      this_shot := this_shot`5E.next;
X    END;
X  qio_write (out);
X
X`7B replace shots `7D
X  out := '';
X  this_shot := head_shot;
X  WHILE ( this_shot <> nil ) do
X    BEGIN
X      this_shot`5E.y_posn := this_shot`5E.y_posn - 1;
X      IF ( this_shot`5E.y_posn <= 1 ) then
X        delete_shot
X      ELSE
X        BEGIN
X          shot_deleted := false;
X          FOR n := 1 to max_aliens do
X            IF ( this_shot <> nil ) then
X              IF ( x_alien`5Bn`5D = this_shot`5E.x_posn ) and
X                 ( y_alien`5Bn`5D = this_shot`5E.y_posn ) then
X                BEGIN
X                  alien_alive`5Bn`5D := false;
X                  delete_shot;
X                  score := score + y_alien`5Bn`5D div 2;
X                  boom (n);
X                END;
X        END;
X
X      IF not shot_deleted then
X        BEGIN
X          this_shot`5E.y_posn := this_shot`5E.y_posn - 1;
X          IF ( this_shot`5E.y_posn <= 1 ) then
X            delete_shot
X          ELSE
X            BEGIN
X              shot_deleted := false;
X              FOR n := 1 to max_aliens do
X                IF ( this_shot <> nil ) then
X                  IF ( x_alien`5Bn`5D = this_shot`5E.x_posn ) and
X                     ( y_alien`5Bn`5D = this_shot`5E.y_posn ) then
X                    BEGIN
X                      alien_alive`5Bn`5D := false;
X                      delete_shot;
X                      score := score + y_alien`5Bn`5D div 2;
X                      boom (n);
X                    END;
X              IF not shot_deleted then
X                BEGIN
X                  out := get_posn (this_shot`5E.x_posn,this_shot`5E.y_posn)
V + '`7C' + out;
X                  this_shot := this_shot`5E.next;
X                END;
X            END;
X        END;
X    END;
X  qio_write (out);
XEND;
X
X
XPROCEDURE  Move_aliens;
XVAR
X  nu : integer;
X  out: v_array;
XBEGIN
X  FOR nu := 1 to max_aliens do
X    IF ( alien_alive`5Bnu`5D ) then
X      BEGIN
X        out := get_posn (x_alien`5Bnu`5D,y_alien`5Bnu`5D) + ' ';
X        y_alien`5Bnu`5D := y_alien`5Bnu`5D + 1;
X        IF ( x_alien`5Bnu`5D = 2 ) then
X          d_alien`5Bnu`5D := 1;
X        IF ( x_alien`5Bnu`5D = 39 ) then
X          d_alien`5Bnu`5D := -1;
X        x_alien`5Bnu`5D := x_alien`5Bnu`5D + d_alien`5Bnu`5D;
X
X        shot_deleted := false;
X        this_shot := head_shot;
X        WHILE ( this_shot <> nil ) and not ( shot_deleted ) do
X          BEGIN
X            IF ( x_alien`5Bnu`5D = this_shot`5E.x_posn ) and
X               ( y_alien`5Bnu`5D = this_shot`5E.y_posn ) then
X              BEGIN
X                alien_alive`5Bnu`5D := false;
X                delete_shot;
X                score := score + y_alien`5Bnu`5D div 2;
X                qio_write (out);
X                boom (nu);
X              END;
X            IF not shot_deleted then
X              this_shot := this_shot`5E.next;
X          END;
X
X        IF not shot_deleted then
X          IF ( y_alien`5Bnu`5D = 21 ) then
X            BEGIN
X              alien_alive`5Bnu`5D := false;
X              qio_write ( out );
X              IF ( x_alien`5Bnu`5D mod 4 = 0 ) then
X                BEGIN
X                  gun_working`5Bx_alien`5Bnu`5D div 4`5D := false;
X                  qio_write ( get_posn (x_alien`5Bnu`5D,21) + '*' );
X                END;
X            END
X          ELSE
X            qio_write ( out + get_posn (x_alien`5Bnu`5D,y_alien`5Bnu`5D) + a
Vlien_type`5Bnu`5D );
X    END;
XEND;
X
X
XFUNCTION  Person_killed : boolean;
XVAR
X  i : integer;
X  temp : boolean := true;
XBEGIN
X  for i := 1 to 9 do
X    if gun_working`5Bi`5D then
X      temp := false;
X  person_killed := temp;
XEND;
X
X
XPROCEDURE  Show_score;
XBEGIN
X  score := score - ( penality div 10 );
X  penality := penality mod 10;
X  IF score < 1 then`20
X    score := 1;
X  posn (23,24);
X  qio_write (dec(score)+' ');
XEND;
X
X
XBEGIN
X  Initialize;
X  start_screen;
X  setup;
X  REPEAT
X    sleep_start (20);
X    show_score;
X    get_command;
X    move;
X    create_aliens;
X    move_aliens;
X    posn (1,1);
+-+-+-+-+-+-+-+-  END  OF PART 1 +-+-+-+-+-+-+-+-