ZX Computings - OpenLibra

meant the addition to its
repertoire of such functions as
logs and trig. These, together
with its ability to PLOT pixels
(quarter square graphics)
means you can draw, among
other things, sinewaves
across your TV screen to your
heart's content!
Another advantage of the
new 8K ROM is the option of
adding a printer to your
system. The ZX printer offers
full alphanumerics across 32
columns and the ZX81
has the commands
necessary to LPRINT and
LUST to the printer.
It also has the facility to COPY,
which will print out exactly
what is displayed on
the TV screen without further
commands.
ZX COMPUTING SUMMER 1982
Programming
Techniques
For those not familiar with the
ZX80, the ZX81 uses a 'one
touch' keyword entry
technique — when you have
entered a program line number
the next requirement must be
a command of some
description. The ZX81
recognises this necessity and
the next single key pressed
will result in the related
command being entered and
appearing on the screen in
front of you. If you have
entered a line number and then
press key 'P' you will actually
enter PRINT, press 'H' and get
GOSUB, and key 'N' gives
NEXT. Likewise, after THEN a
command is expected: key 'P'
again gives PRINT, 'Y' gives
Review
RETURN, and so on. Many
keys are multifunction: some
are capable of generating up
to three keywords, a letter,
that letter reversed and also a
graphics character!
Initially this can be a little
daunting, not to say
confusing, but you will soon
get used to the operation of
the keyboard. It has a fairly
logical sequence and like any
new keyboard can pose an
unfamiliar operator with a few
initial problems.
The cursor takes the form
of a reversed character: if 'K'
is displayed this indicates that
a keyword will be generated,
should the next key pressed
have such a function. If the
cursor displays a 'G' then
either a graphics symbol or a
reversed character will appear.
A reversed 'F' indicates that a
further set of keywords such a
SIN, COS, RND will be called
Should a reversed 'S' be
displayed then you have a
syntax error and the ZX81 will
not 8llow the entry of that line
to the program until you have
made the necessary
correction.
Reading Matters
The manual has 28 chapters
and three appendices. Chapter
one gives instructions on how
to connect and set up the
ZX81 for operation initially. It
also recommends that those
already knowing BASIC should
read Appendix C to familiarise
themselves with ZX81 BASIC
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