Akalabeth Main Game File

Commands

The command loop and command handling is done in lines 1000–1700.

First we go to the bottom of the screen and print the prompt. CALL -868 clears the line to the right of the cursor:

1000  VTAB (24): PRINT "COMMAND? ";: CALL  - 868

Then we loop until we get a key press:

1001 X =  PEEK ( - 16384): IF X < 128 THEN 1001

We see how much memory is available (not yet sure why):

1002 Q =  FRE (0)

and reset the keyboard:

1010  POKE  - 16368,0

Command Dispatch

Many commands are handled differently depending on whether we're outside or inside.

These commands are:

• CR (141) NORTH 1100 or FORWARD 1150
• RIGHT ARROW (149) EAST 1200 or TURN RIGHT 1250
• LEFT ARROW (136) WEST 1300 or TURN LEFT 1350
• / (175) SOUTH 1400 or TURN AROUND 1450
• X (216) GO 1500 or 1550
• A or 27 (193 or 155) ATTACK 1600 or 1650

SGN(INOUT) will be 0 if we're outside and 1 if we're inside.

1030  IF X = 141 THEN  ON  SGN (INOUT) + 1 GOTO 1100,1150
1040  IF X = 149 THEN  ON  SGN (INOUT) + 1 GOTO 1200,1250
1050  IF X = 136 THEN  ON  SGN (INOUT) + 1 GOTO 1300,1350
1060  IF X = 175 THEN  ON  SGN (INOUT) + 1 GOTO 1400,1450
1070  IF X = 216 THEN  ON  SGN (INOUT) + 1 GOTO 1500,1550
1080  IF X = 193 OR X = 155 THEN  ON  SGN (INOUT) + 1 GOTO 1600,1650

SPACE passes:

1081  IF X = 160 THEN  PRINT "PASS": GOTO 1090

S shows stats/inventory:

1085  IF X = 211 THEN 1700

P toggles PAUSE ON/OFF which we store as PA (1 for ON, 0 for OFF):

1086  IF X = 208 THEN  IF PA = 1 THEN PA = 0: PRINT "PAUSE OFF": GOTO 1000
1087  IF X = 208 THEN  IF PA = 0 THEN PA = 1: PRINT "PAUSE ON": GOTO 1000

Note that PAUSE ON/OFF doesn't call the Post-Command code (so doesn't reduce food, etc)

Any other keys and we print "HUH?" and go back to the start of this routine:

1089  PRINT "HUH?": GOTO 1000

Post-Command

Once the command is executed we normally GOTO line 1090.

First we reduce food by 1 (or 0.1 if we're inside). If FOOD hits 0 then we set HIT POINTS to 0 too, announce the player has starved and go to line 1093 (which in turn will send us to the Death routine at 6000)

1090 PW(0) = PW(0) - 1 +  SGN (INOUT) * .9: IF PW(0) < 0 THEN C(0) = 0: PRINT : PRINT "YOU HAVE STARVED!!!!!": GOTO 1093

If we haven't starved, though, we update our FOOD / HIT POINTS / GOLD display:

1091  POKE 33,40: VTAB (22): HTAB (30): PRINT "FOOD=";PW(0);: CALL  - 868: VTAB (23): HTAB (30): PRINT "H.P.=";C(0);: CALL  - 868: VTAB (24): HTAB (30): PRINT "GOLD=";C(5);: CALL  - 868: POKE 33,29: HTAB (1)

We round our FOOD to one decimal place.

1092 PW(0) =  INT (PW(0) * 10) / 10

If HIT POINTS are zero or less, we go to the Death handling routine:

1093  IF C(0) <  = 0 THEN 6000

If we're in a dungeon (IN is same as INOUT) we move the monsters around. If this has resulted in HIT POINTS being zero or less, we go back to the previous line to go to the Death handling routine.

1095  IF IN > 0 THEN  GOSUB 4000: IF C(0) <  = 0 THEN 1093

The following is the same as line 1091. I guess we do it again because the monster movement in the previous line may have changed some values.

1096  POKE 33,40: VTAB (22): HTAB (30): PRINT "FOOD=";PW(0);: CALL  - 868: VTAB (23): HTAB (30): PRINT "H.P.=";C(0);: CALL  - 868: VTAB (24): HTAB (30): PRINT "GOLD=";C(5);: CALL  - 868: POKE 33,29: HTAB (1)

Not yet sure what GOSUB 100 or GOSUB 200 do. Perhaps draw.

1097  IF INOUT = 0 THEN  GOSUB 100: GOTO 1000
1098  IF INOUT > 0 THEN  GOSUB 200: GOTO 1000