Wombat Combat



D Green

Ashford,

Kent.



Can you guide the wombat down into the underground chambers

of Deep Fort to destroy the Mad Master computer lurking

there? I hope so. The fate of Western Civilisation rests on

your 48K Spectrum.

  The game utilises an apparently unique method of regis-

tering damage, as each one of the three main systems of

the wombat has its own damage monitor and is affected by

different hazards. Other potential dangers on your mission

include the moderately brain-dead flying robot and boun-

cing missiles, against which your most effective forms of

defence are either running away or using your unbelievably

short range tactical nuclear weapons, activated by key 0.

Use the arrow keys to move, or change them in lines 160

and 170.

  Since the actual destruction of the master computer is

not really all that hard, to get a reasonable score of over

2000 points you also need to collect all of the batteries

that are lying around by some improbably coincidence. These

batteries and various other objects have somehow been

granted the power of levitation and hover in the air. The

wombat is susceptible to falling if there is nothing to

support it.



  The program is a good example of sound effects overkill,

since hardly anything ever happens in total silence. The

five mindless tunes embedded in the game are all done from

Basic, but to show that the Spectrum can do more than beep,

two machine-code routines are used. If you want to experi-

ment with these, then have a look at line 2790, which sets

up the variables to be used as follows:

Poke lf, low (least significant) byte of frequency

Poke hf, high (most significant) byte of frequency

Poke len, number of beeps to be made

Poke bep, length of each beep

  Then use Usr urun for a sound effect that goes up in

pitch, or Usr drun for a sound effect which goes down in

pitch. Be very careful when using numerically low frequen-

cies, as if an uprunning sound effect goes into negative

frequency values then a boring breakproof beep will occupy

your computer for anything up to several hours.

  The amazingly efficient language of machine code is also

used to detect user-defined graphics and to move the mis-

siles. Note that all this machine code means that multiple

saves before running are essential, as checksums can't find

all your errors and just one poke can send all 16K of

program to that great Ram chip in the sky.

