Once again Sinclair offers value for
money with a vengeance - colour, sound and graphics for £125!
David Tebbutt reports.
Well, he's done it again, hasn't he? Uncle
Clive has gone and shown the world how to produce a decent
colour personal computer at the sort of price only he can
conceive. Two versions of the Spectrum are available - 16k
and 48k at £125 and £175 respectively, including
VAT. If you want to upgrade your 16k machine to 48k later
on, it will cost you £60. At the moment, the machines
are available only by mail order. The Spectrum (ZX Spectrum
to be precise) offers colour, high resolution graphics and
sound and, at the price, it has just got to be the best value
for money around.
Like most computers at this level, the Spectrum
plugs into the domestic television and uses a normal cassette
recorder. The ZX printer can be attached and, with a little
modification, ZX81 programs will run happily on the Spectrum.
A £50 miniature disk drive (the ZX
Microdrive), communications facilities and an RS232 interface
will be announced later on.
Hardware
The Spectrum measures just 233x144x30mm
and weighs in at 520 grams excluding the separate power supply
and cables. It looks extremely elegant and, unlike its predecessors,
it has keys that actually press down.
You'll not be surprised to learn that there
are hardly any components inside the machine: 14 chips, a
UHF modulator, a piezo-electric 'speaker' and an assortment
of capacitors, resistors, diodes, crystals and a coil make
up the complement. I swear that some of my crystal sets had
more in them. All this is mounted on a single board and, looking
underneath this production prototype, I notice that there's
not a single patch. The only odd thing about it is that there's
a big blob of green plasticine stuck around the coil. The
coil on the review machine does whistle a bit but I understand
that production machines come with suitably lacquered coils
to eliminate this problem.
A hefty edge connector at the back brings
out just about every signal you could wish to have. This is
used for printers, communications and disk drive connections.
Inside there are two spare sockets which accommodate each
end of the 32k memory expansion board. This is a great improvement
on the ZX81 memory expansion which tended to drop off the
back of the machine at the least provocation. Talking of sockets
(well I was, just now) every chip except the ULA is socketed.
The reason the ULA isn't is because it gets darned hot - putting
it on the PCB allows the heat to dissipate better.
The keyboard comprises a one-piece grey
rubber moulding mounted over a pressure-sensitive membrane.
The keys poke up through holes in a black metal plate and
I must confess the feel is more that of a calculator than
a typewriter. Most keytops have three symbols on them and,
in addition, most of them have another two associated inscriptions
printed on the metal surround. If you're anything like me
you'll find yourself reading the whole keyboard each time
you want to find a function. You do get used to it after a
while: in my case it took a couple of days. I found that red
symbols on grey keytops are quite difficult to read and, thinking
my eyesight might be going, I showed the machine to a number
of friends, all of whom had the same difficulty. I showed
it to my 11-year-old and he thought it was just fine, though.
A power supply is included in the price,
so there's not a lot of point risking one of your own and
blowing the Spectrum up. The two cassette leads terminate
in 3.5mm jack plugs so be sure that they work with your recorder
before you embark on any major programs. It took me four or
five tries before I found the right volume setting on my tape
recorder. Once this was found, though, program loading presented
no problems.
l tried the Spectrum on three televisions
and the results matched the quality of the sets used. The
display comprises 24 lines of 32 characters with the bottom
two lines reserved for messages and entries. The display can
also be regarded as 176 x 256 resolution for graphics work.
High resolution graphics work is best done in two colours
as you will see in the firmware section of this review. The
screen, border and individual characters can each take on
one of eight colours and, in addition to this, characters
can be bright or flashing. Other screen attributes like inverse
and overprinting relate to the whole screen. More on these
later,
The single channel BEEP facility is about
what you'd expect from a piezo-electric speaker. It does sound
slightly better amplified from the cassette port but it's
still pretty awful. A couple of octaves around middle C aren't
bad; but the other eight are best used for sound effects.
At the high end they warble and at the low end they grate
- BEEP is a refreshingly honest description.
Really, there's not a lot more to say about
the hardware. It is a very professional job - looks smart,
works well and manages to squeeze 191 legends on to just 40
keys!
Firmware
Here's a new section for PCW Benchtests.
All the software on the review machine was in the ROM chip
which also contained the character set. This time Sinclair
has gone for a basic ASCII set (upper and lower case) with
the addition of both built-in and user. defined graphics characters.
Outside of the range SPACE to QUOTES (32 to 126), many of
the codes have special values relating to Spectrum keys and
functions. For example, you'll find a copyright symbol key.
(Now why didn't anyone else think of that?) You can define
up to 21 characters of your own.
Two screen tables are maintained in memory
- one for the displayed characters themselves and the other
for the attributes which describe how they're to be displayed.
These attributes can be tested from within a Basic program.
The character colour is referred to as INK while the background
colour is called PAPER. Isn't that sensible? Each character
can have its own value for INK, PAPER, FLASHING, BRIGHTNESS,
INVERSE and OVER. The last two should be explained: INVERSE
simply means that the dots which form the character are printed
in the PAPER colour while the PAPER is printed in the INK
colour. OVER is special: it allows you to merge a new character
with the one already at the screen position. The rules are
that two INKs or two PAPERs print PAPER otherwise it prints
INK. This means that you have a neat way of removing the last
thing printed and restoring what was there before it.
By now you have probably realised why it
is best to stick to two colours when doing graphics work.
Since the colour of the INK and PAPER relates to a whole character
position, then each time a new colour graphics point is set
all other set points within the boundary of that character
are set to the new colour. This makes for a very curious effect
to say the least.
Mathematical accuracy is to 9½ decimal
digits and a fairly full range of mathematical functions is
accessible from the keyboard. While on the subject of keyboards,
this one has a built-in software 'click', an upper-case lock
key, and automatically repeating keys. Like the ZX80 and ZX81
before it, the Spectrum makes great use of single-stroke keyword
entries. In fact, I think every standard function and command
is obtainable in this way. You'll even find things like >=
and <=.
Basic
The Spectrum comes with a very useful version
of Basic. It will be quite familiar to anyone who is used
to the Microsoft types of Basic and a doddle to learn for
those new to the language.
Rather than go through all the features
and functions of the language, I have summarised them in a
separate box. Here, I'll just comment on the unusual and interesting
aspects of this particular implementation. Unlike some Basics,
it is a teeny bit strict about things like using LET before
assigning a value to a variable name or putting G0TO after
a THEN. My view is that this is all jolly good discipline
and it is more than compensated for by the fact that Spectrum
pops in all those spaces which make programs so much easier
to read. Of course, once you've found your way round the keyboard
the single stroke keyword entry is a joy. (I've got a feeling
I said that in my last two ZX reviews.)
SAVEing and LOADing cassette tapes gives
plenty of scope on this machine. You can save a program normally,
you can save it so that execution starts automatically when
it is reloaded, you can save arrays, you can save particular
chunks of memory and if you want to keep a pretty picture
you've created then you can use the SCREEN$ option to save
that too. All saved programs can be verified after saving.
The screen save can't be verified because the display is changed
during the verify program and it would not then match that
held on tape. The LOAD command can, of course, handle any
tape created by SAVE. The MERGE command allows you to merge
a program on tape with one already in memory. Program lines
which are duplicated are overwritten while all others are
suitably interleaved.
The graphics facilities are great fun. You
can draw straight lines, curves and circles on the 176x256
pixel (Picture Element, or dot) window. Position 0,0 is at
the bottom left-hand corner of the screen. You can define
up to 21 graphics characters of your own which is a superb
feature if you're into writing your own Space Invader or Pack-Man
games. I had a lot of fun drawing and animating little people
on the screen. The nice thing is that you can do all this
sort of thing without leaving Basic. A BIN (binary) notation
has been introduced which allows you to define numbers as
a series of 0s and 1s - just the ticket for designing funny
characters. Each character comprises eight lines of eight
points, so a succession of eight BIN numbers is all you need
to define such a character. Another use for user-defined graphics
is to squeeze some extra colours out of the machine. If you
lay out the 64 pixels like a chess board and choose suitable
INK and PAPER colours then you can get some interesting effects.
Most of them will be awful but persevere - some will be good.
You won't be surprised to learn that line
drawing and circle plotting are achieved using the DRAW and
CIRCLE commands. A PLOT command allows you to plot single
points. POINT enables you to find out whether a particular
pixel is set. You always DRAW from where Spectrum thinks you
are on the screen. for example, a command DRAW 10,10,pi would
draw a semicircle ending up 10 places to the right and 10
above the current position. A fraction of pi would provide
a different arc while zero, or no third argument (DRAW 10,
10) would draw a straight line. The curve can be drawn on
either side of the centre line by making the third argument
a positive or negative number.
The CIRCLE command uses three arguments:
x-axis, y-axis and radius. Remember, the OVER command can
be used to erase something already drawn. I used this feature
in conjunction with DRAW, PLOT and CIRCLE to create cartoon
effects. OVER is also useful for embedding text in a drawing.
When set on, the text merges with the existing lines in the
drawing. When set off it prints the full 8x8 character, completely
replacing anything already displayed at that position. Incidentally,
SCREEN$ can be used to return details of the contents of a
character position. Used in conjunction with the PRINT AT
command, this could be a good way of making your program find
a suitable place to print a sort of 'label' on a drawing.
The AT allows you to define the row and column at which printing
should start.
A few instructions I particularly noticed
as I went though the manual were READ, DATA, RESTORE and VAL$.
READ and DATA are old friends although I can't remember them
being on previous ZX machines. Using the DATA command you
can provide lists of information at the beginning of a program
Each READ instruction takes the next word from this list.
RESTORE can be used to set the DATA pointer to any DATA statement.
VAL$ baffles me - it strips the outside quotes from string
expressions and returns the string value of the result. Perhaps
some kind reader would care to suggest a worthwhile application
for this feature.
Now let's have a look at our honestly named
friend, BEEP. There's not a lot to tell, really, except that
you can control both pitch and duration. Notes below middle
C are represented by negative numbers, those above by positive.
Twelve numbers make an octave. (If you look at a piano keyboard
you'll find that there are seven white notes and five black
notes per octave.) Middle C is zero. The duration is expressed
in seconds or fractions of a second. As I mentioned earlier,
the sound isn't brilliant but it has the saving grace of being
fairly quiet (ComputerTowns please note). You can pick this
sound up from the cassette ports if you so wish. I'd say these
facilities are more likely to be used for sound effects than
composing symphonies.
That's really all I have to say about the
Basic. It is a very good implementation for a machine of this
size. A PAINT instruction would have been nice to fill in
graphics shapes, but I think it would look a bit weird in
multicolour mode with the colours changing at each character
boundary. A routine to do this should be simple enough. I
think the screen resolution is quite adequate for most personal
users of the machine. In fact you can churn out some quite
stunning effects using DRAW, PLOT, CIRCLE and the user-defined
characters.
Before moving on to documentation, here's
a list of the disk commands just to whet your appetite: CAT,
CLOSE, DELETE, ERASE, FORMAT, MOVE, OPEN. CAT is probably
short for Catalogue which lists the files on a disk. MOVE
probably copies a file from one place to another. The others
are self-explanatory.
Documentation
Two manuals come with the Spectrum - a thin
but useful introduction for the complete novice and a thicker
one which explains things in depth. A lot of effort has been
put into this latter manual. It is professionally presented
and easy to read. Unfortunately, I was given a photocopy of
the final proofs and it contained no index and no table of
contents. I read the whole manual a couple of times before
starting the review and I found it a real problem to find
things that I knew where there somewhere. I must admit that
the style wasn't to my liking it's a little verbose and the
individual chapters seem to lack structure. I also found the
inevitable errors which might cause a beginner problems -
things like a minus sign being printed instead of equals,
for example. The manual certainly seems to cover everything,
so if a table of contents and comprehensive index are added
you'll probably find it adequate. It's certainly an improvement
on many manuals on the market.
Potential use
This is the first machine that I've reviewed
since the Atari two summers ago that I would actually buy
- in fact I will have probably ordered one by the time you
read this. I would use it for fun, for fooling around with
graphics and for programming in Z80 code. I would treat it
as a hobby machine, a way of relaxing. My children have already
become very interested in the graphics capability and I see
this as a way of giving them a real understanding of mathematics.
A Logo system on this at the right price would go down an
absolute treat - if anyone out there thinks of doing it, I'd
love to review it. Of course, there are those who want to
learn to write programs. Once again, this is an excellent
machine to cut your teeth on. I think that schools and homes
have got to be the prime targets for Spectrum at the moment.
Later on when the disk drives appear this
may change. At a predicted £50 for a 100k drive, a lot
of people who will have written the Spectrum off as a hobby
machine will have to think again. Add to that a £20
combined RSZ32 and communications facility, and you could
be talking about some very interesting and fairly sophisticated
networks. At that stage, it becomes a very real prospect for
schools looking for a fairly grown-up system, but one which
can involve as many pupils as possible. At Sinclair's prices
could we possibly be heading for the 'one on every desk' scenario
painted by so many futurologists?
Until those disks arrive there is no great
office potential for the Spectrum. Once they're on stream
then it's probably just a question of appropriate software.
Information management and Visicalc.type applications would
seem to be the most likely and, because of the price of the
television, they will probably be used with portable black
and white machines. No doubt the dedicated will take their
Spectrums (or is it Spectri?) home to plug into the colour
TV Most people will probably wait until Sinclair announces
a flat screen colour television. The network idea could then
be useful in offices for things like telephone directories,
noticeboards and memos.
Conclusions
Well, for the benefit of those who only
read the first and last paragraphs of these reviews, here
are my conclusions: Clive Sinclair has produced a very good
16k personal computer which offers colour, high resolution
graphics and limited sound for just £125. That represents
very good value for money provided that this is the sort of
machine you want. It is ideal for people who want to learn
about computing and have a lot of fun while they're doing
it. Given the right sort of graphics-based educational software,
it can bring people very pleasurable ways of learning subjects
such as mathematics and geography. Once the games programs
start to appear, a lot of people will use it just for that,
although it does seem a bit of a waste.
Later on, the provision of disk drives and
communications facilities will make it an even more serious
contender for the school markets and it will begin to creep
into businesses. When the flat screen television appears then
I suspect that the business interest will rise because the
price will be far more appropriate. Bulletin boards, memos,
telephone directories, spreadsheet calculation and information
management seem to be the most likely applications.
The 'proper' keyboard is a distinct improvement
on its predecessors, but it still doesn't achieve - or try
to achieve - the quality of an IBM. All the old regular Sinclair
features are included - the single keyword entry and the automatic
syntax checking as you enter each command, for example.
My verdict? The best value for money you
can find today!
What about the '81?
It was no secret that 'Uncle' Clive was
going to launch a knockout micro - he's put a bomb under the
industry twice already, producing machines which brought computing
power within everybody's reach at prices which drastically
undercut the competition.
A slightly upmarket (by Sinclair standards)
machine offering colour and sound and reasonable graphics
at a price far, far below that of any equivalent machine was
a logical step to take, especially in view of Sinclair's obvious
annoyance at being left out of the BBC deal.
What is interesting, though, is that the
Spectrum does not replace the ZX81, as the 81 did the 80 -
it's an addition to the range and the ZX81 will continue in
production. In fact, production of the 81 is to be increased
to a target of 150,000 a month by the end of the year.
'The ZX81 will continue to be ideal for
the person who wants the lowest possible entry cost into computing,'
says Sinclair. And to prove the point, he's knocked £20
off the price of the 16k RAM pack.
At the moment Spectrum is available only
by mail order and is only on sale in the UK - there are no
plans yet to market it through retail outlets, as is done
with the ZX81 through W H Smith, and export versions are not
planned until the end of the year, with the USA being the
first (and largest) market to get the new machine.
Prices (inc. VAT @ 15%)
