Special Features

Finally, let’s have a look at a Spectrum program
written by Tim Hartnell to demonstrate a number of the
new computer's features. Examining the listing, and then
trying out the program when you get your computer will
explain much of the computer’s new features to you.

l believe that Uncle Clive has done it again. He has
produced a splendid mass-market computer which a
sizeable percentage of the population will want to buy.
Apart from the ‘fiddly’ keyboad, it is very easy and user-
friendly. My only wariness comes from the delivery
times. Sinclair Research have never managed to keep to
delivery schedules, and the extreme shortage of review
machines suggests it will be some weeks before any
become available for buyers.

How It Runs

The program, Conway's Colony, is a version of
LIFE, the program first developed by John Conway who
was at that time attending Cambridge University. You
can see that the computer allows variable names to have
spaces in them, as is shown by line 30 (where the
variable is called ‘print colony’) and by line 40 (‘genera-
tion update’). The whole program cycles from line 50 to
70, over and over again. The routine from lines 90 to 180
sets up the starting conditions. Line 135 changes the
BORDER (the ‘frame’ around the main display area) at
random, producing a quite dramatic display as the initial
colony is set up. The BEEP command in line 140 shows
the parameters of a BEEP can be fractions of numbers or
results of a loop. This produces a splendid, constantly
changing effect, as the x and y loops are executed. Note
that multi-statement lines (see line 160 and line 140, for
example) are possible for the first time on a Sinclair
colfnputer. They are linked by a colon, available from the
Z key.

Line 250 shows a number of PRINT statements
linked and the word ‘Generation’ in inverse letters. ln-
verse letters are available directly from the keyboard by
holding down the white shift key, then pressing the key.
Everything from then on will appear white on black.
Holding down the white shift key again, and pressing the
key, will return you to normal video.

Line 345 changes the border colour at random,
producing a very interesting effect which does not slow
down the processing at all. The cells are printed by line
285 as an inverse little square. The colour of the square
is chosen at random (INK RND*6) and this produces a
very attractive display. Examing this listing should tell
you quite a bit about the Spectrum.