Popular Computing Weekly (1982-09-02)

WEEKLY

2 Saptanitiw 1982 Vol 1 Mo 20

We test the new
Commodore 64

'^Jj^tttOeymaVBO

«

'QUI 2X31 plmlh we have ir

le Spectrum, Tnis slylish ABS clinth raises am

'" ^r vjewing whilst angling the Spectrum and

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Nick Hampshire

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2 SEPTEMBER 1982

This Week

Laserbug rings the changes.
Lcttera

Sinclair speaks.
Under Pressure

w game tor Spectrum by Simon

Davkj Kelly reports on SllvBrsolt.
Benchtest

ZXCalaxlans.
Open Forum

ilf pages of your programs.

Skelch & draw.
Sound A vision

little peace (or Vicao.
ProgrBmrolrtg

Upgrade your BBC to 32K.

YourquBslionBi
Competition

Editorial

The queslion of software copyright Is
rearing its head again. Atari has
started a campaign against programs
which allegedly infringe the copyright
of its Pac-Man game.

As part of that campaign, Atari Is
seekirtg an Injunction against Com-
modore. Atari Is alleging that Com-
modore's game Jellymonsters Is an
Infringement of copyright.

Other software companies, such a
Bug-Byte, A and F Software and
Micropower. have also been
approached by Atari.

There could tie severe repercus-
sions for the software industry, if any
of these cases come to court. If the
court decides that copyright suOsists
in computer programs, and/or in
Images repnxluced on a iv screen
{PCW. August 5). then companies will
be forced to develop more original
games. Imitations of successful
arcade games such as Space Invad-
ers will no longer be acceptable.

The establishment of a precetteni
for software copyright can only be
good tor the industry. Software firms
and writers alike will finally kn<
where they stand in regard to the la

Next Week

M

Can you save Beta
Strigldae trom attack by winged
reptiles— find out InPteragon.a
new game for BBC

Our classifieds
are faster.

Do you want to sell your computer and
buy a bigger and belter one?

Have you ever thought of trying to
make some money out of selling tapes of
your own programs?

Whatever it is you want to buy or sell
why not use our classified pages?

It has to be better than wailing for up to
nine weeks to get into one of the old
monthly magazines.

Not only Ihal, but our rates are very
reasonable.

For private individuals it only costs 20p
per word, with a minimum ol 1 words.

We can make it so cheap because we
charge companies using the classified
columns 40p per word.

The classified pages can be used for
semi-display advertising.

The cost for this is £i per single
column centimetre, with a minimum
charge of E30-

All copy for the classified pages must
be pre-paid. (You'll find a handy form on
page 25.)

Cheques and postal orders should be
made out to Popular Computing Weekly.
Your advertisement should arrive at least
two weeks before the publication date.

If you have any queries regarding
Classified or semi-display
advertising please call
Alastair Macintosh on
01-930 3840

Popular Computing Weelcly.

The fast one.

News Des K

01-930 3271

in ZXKI

Spectrum
software
converter

[T is now possible
software on the ZX Speclr

The new software conver-
sion device is called )tie Slow-
loader and is manufactured by
East London Robotics.

The hardware'software
combination is easy to use and
allows ZXSl software casset-
tes to be loaded and correctly
interpreted by the Speclrum.

board is plugged into the I/O
port on the rear of the Spec-
machine-code routine is then

the usual manner. The ZX&l
cassette is then loaded through
a socket on the Slow loader

through the normal cassette

Mark Vellacott of East Lon-
don Kobotics explained that
the device converts the ZX81
coding as the tape ii loading.

"The Slowloader." he said,
"handles string arrays intel-
ligently — converting them to
Specirum characters — and
will also successhilly cope with
ZX81 machine-code programs
providing they do not alter the
screen display or define new

The Slowloader will cost
about £11] and will be available
from the beginning of Septem-
ber,

Further information from
East London Robotics, Fin-
landia House. 14 Darnell
Close, East Ham, London E6.
(Tel: 01-471 3308).

Computer grant
double boost

Information Technoloj
Minister. Kenneth Bake
annouacing a £13m plan, sa
thai Che need for such inve
Under tt

lemc. up to
.t of such t

Laserbug tackles
its problems

LASERBUG, i
South-East BBC microcompu-
ter user group has appointed
its first full-lime co-ordina(oi
Paul Barbour is to be the

duce the group's monthly

He will replace Trevor Shar-
pies who has resigned from
editorship of the newsletter,

Trevor Sharpies told Popu-
lar Computing Weekly that he

with the group having been
"forced to give up the club
because of time considerations
and personnel difficulties".

Only two of the monthly
issues — April and May —

the group's 2000 members,
Paul Barbour explained that a
joint June/July issue was being
sent out. A joint August/
September issue is to follow.
He said that every member
would have their subscription

eilended by two months to
compensate for the delay,

operate from its mailing
address — 4 Station Bridge.
Woodgrange Road. Forest
Gate. London E7, There are
no plans for Laserbug to have
a telephone installed.

Sinclair gets going

SINCLAIR Re'

financial help to a campaign to

help create jobs from private

enterprise.

The company is contributing
£lDOa of the £lU,(Xn prize

of the Daily Star newspaper's
'Get Going' competition.

The 'Get Going' winner wiil
be the individual who comes
up with (he best idea which
could lead to the setting up of
a successful smalt business and
the creation of job opponuni-

going', and the n

ve£20a.

five-figure prize money in-
clude British Petroleum, The
Confederation of British In
dustry. National Westminstci
Hank, Plessey. Sainsbury'i
and the Science and Engmeer
ing Research Council.

The competition closed or
August 31 and the wirmers wil

The first prize w

will

Commodore In

copyright

contest

COMMODORE is to contest
the Atari claim of infringe-
ment of the Pae-iWaa copy-
right.

The statement from Com-
modore Business Machines
(UK) Ltd says: "Thetf
several grounc^ which are
troversia! in the Atari claim
and Commodore is conlesting
the case."

In an independent si
recently conducted on behalf
of Commodore, the reactions
of potential purchaser, under
17 years of age. to the Vic20
Jellymonsrers and Atari
Pac-Maa were compared.

A Commodore spokesman
said: "Initial results suggest
that on several parameters,
including graphics, sound and
enjoyment, there is an 80 per-
cent preference amongst con-
sumers towards Jellyaionsteis.

"TTiis tends to conflict with
the claim of Atari Internation-
al (UK) Inc thai Commodore
Business Machines (UK) Ltd
IS in conflict with cons

Atari is pressing ahead with
its claim for an injunclion
against Commodore to stop
sales of Jellymonslers.

A spokeswoman for Atari's
advisers said: "Tliere will be a
hearing in October, when
Atari will claim injunctive re-
lief against Commodore."

Change In Vic
software poHcy

COMMODORE has adopted
policy of linking its Vic car
tridge software to well-knowi
personalities or institutions.

The first of these avaiJable i
Mastermind, marketed by
arrangement with the BBC
and with questions set by the
BBC Mastermind co-
ordinator, Bosweli Taylor.

Next month will see a cook-
ery package from Robert Car-
rier and a personality testing
program from Professor

sion of Ask the Family, again
by arrangement with the BBC,
and a link-up to produce edu-
cational software in conjunc-
tion with the publishers. Hod-

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POPULAR COMPUTING WEEKLY

Letters

write to Letters, Popular Computing Weekly, HobhouM Court, 19 Whitcomb Street, London WC2

Wash a matter
with you baby?

ihe BBC micro and the ZX
Spectrum . He implies that the

Some people may piefcr the

ideas being "re-hashed" and
submitted. In thai very issue
there is a mastermind prt)g-
tam. Now. if there is a ZX81
owner in the world who has
not already seen 20 master-
mind programs i

pie who consider il wonhwh
paymg more for the BBC mic-
ro's adaptability and extra

I had not thought of controll-
ing a washing machine by my
BBC, but Michael Vale has
just given me a good idea,

RLober

Rivendell

13 Pwll-Y-min Crescent

/Vrertf iin-.vuper- Elv

Cardiff CF5 6L'R

Mown down
by moans?

I am wnting with a moan or
two about the Screen S func-
tion on the Spectrum.

This function is not satisfac-
torily explained in the manual.
When used, it will yield a null
string for any graphic symbol,
including user defined ones.

bols in games almost poinlles.s.
There is also a bug with the
fallowing program :

nswer. But, if you change line

your editorial. Docs the per-

your magazine'? The poinis
raised are \ety interesting a
I agree with many of them. 1
you do not follow your o

In PCM' July :« your edi
Z SEPTEMBER 1962

Id tike tc

On page 19 of thai issue
there is a maths quiz program.
Again, this is a (yawn) well
tried program. On page 15
there is a program to define
Spectrum graphics. An almost
identical program appeared in

In your defence, you have
published some excellent
routines for the Spectrum (eg
the 3D graphics in issue 12)
but 1 feel you do tend lo

PS.

would I

t for

other PCW. Twice they have

which your magazine had
already reviewed ie Spectrum
and now the Dragon,

Stephen Kelly

SO Hialon Cieiceni

Appleton

Warnngmn WA4JDF

Yon are quile right, we da doI

pie. but we da try. In (he case
of Open Forum pn^rams we
have been encourBglng readers

few of these types of garner
together with as many new and
interesting pn^rams as possi-

Or ]u8t a white
elephant at lar^e?

T ike many microcomputer

aware that both the ceefax and
oracle services broadcast telc-
saftwace. Unfortunately, it is
limited to that overpriced
never delivered BBC compu-

tributed (a fact verified by the
computer newsletter published
on page 705 of ceefax). Surely
such a piffiing amount is not
enough to ensure a monopoly
in the telcsoftware output.

pies of pages i '

The general public's re-
sponse to our ne* computer
has far ejiceeded our expecta-

'swamped' with orders. This,
and some small initial produc-

considerable delays in deliv-

n the

widely used languague
home computing world. After
all, half a million ZX81 com-
puters and more than ^U.OUO
Sped rums have been sold
already in this country.

1 am quite sure the BBC will
say that they do not have
enough pages on their teletext
service to cater for any other
software. The real reason
being that they are unable to
admit Ihat their computer is
rapidly becoming a while
elephant in the light of the

ters being produced, and
under development.

Could you not ask your
readers to pester the BBC with
a vie* to getting such prog-
rams broadcast. After all, we
are missing out on a fantasti-
cally useful service. The prog-
rams which I have painstak-
ingly transposed to Sinclair
Basic seem to be of very high

NigeJ Cummings
4S6 High Sireel
Wesi Bromwich

If vou read PCW Jul) 29 you
will see thai Sinclair are de-
veloping a Prestd adaptor for
the Spectrum. It will cost loss

able in the first half of next
ye»r. Consequently, there will
also be a range of Spectrum
telesaftware available next

SoRware manufacturers can
sell their programs through
Prestel by cunlacllng British
Telecom on Fmphone 2(R),

Log Jam brills
cash rewards

In response to the many
queries which, I understand,
your Diagazine has received, 1
would like personally to ex-

lo 12 weeks, from our receipt
of their order, for delivery of
their Spectrum, We are writ-
ing to them all to apologise for
the inconvenience and lo offer
them the chance of im immedi-

For those customers who
continue lo wait, we shall be
sending out with each Spec-
trum, in compensation for the
delay, a £10 voucher, which
can be used in part-paymenl
for a ZX Printer or to buy a
complete pack of five rolls of
printer paper.

We are also providing cus-

Finally, 1 would like to
assure you and all oui custom-
ers that the initial problems
with the Spectrum have now

Producfion is running smooth-
ly at 5,000 units pet week and
will rise sharply over the com-
ing months. We ate conBdenl
that our present backlog will
be cleared by the end of
September and hope that you
will see current delays in the
context of our successful deliv-
ery of more than 500000 com-
puters in the last two years.

Clive Siadaii

Sinclair Research Lid

2} Moicomb Sireel

London SWIX SLB

Popular Computing Wceklv.
Hobfiouse Courr. 19 Whh-
comb Street. London WC2.

J5SS0

f*^ Underpressure

Y Itie Yoshima oil rig ir

main lask is Id carry □'
inspection and maintenance of Ihe pic
lines carrying the oil from the rig lo
refinery in Scotland.

It the main pipe line has sprung
»ul 1000 melres away from If
.i^ni,..a rig. YoL are despatched in
propeHer-driven Oiving bell lo mvesttgat

tie pipe line, looking
VIS OS that denote a
e ol

Cruising just at

,. you suddenly Iwcome
strong smell of smoke. Turning round you
t your engine has caught tire.
Grabbing the chemical tire extinguisher
from under your seat, you douse the
engine in a mass of loam.

ut, the immediate danger

ngine is a hwsted heap of
bumt-DLit wire and meial. You are trapped

Fortunalaiy, the diving bell is equipped
with an aqualung and a wel-suit. However,
as you are putting on the aqualung you
notice thai the air cylinder seems slrar)gely
light. On checliing the cylirrfer's gauge.
,. . . ..._. .. Is virtually empty.

ie diving bell starling

Entering thi

attempt to swim lo the surface before your
is out. But, if you rise too fast you will
sutler from "the bends" and die from
decompression.

When you have loaded arid run the
program, a man inawel-suilwill appear on
lefi. Two dials will also appear on
of Ihe display, indicating your depth

Type'(

' 10 use your flippers. This uses

jt doubles your speed.

it watch out lor shoals of fish

and clumps ol seaweed on your way up.

Hitting either ol them will delay your

ihing square appears beside the
oxygen dial when your air supply is almost
exhausted. The key to the game is to keep
rising slightly faster than your air supply
diminishes.

e compute I

a percentage 5<

and your remaining air My

far is 63 percent. Can you bi

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396 JAMES RECKITT AVENUE,
HULL. N. HUMBERSIDE. HU8 OJA

POPULAR COMPUTING '

s

treetLif

e

'

Born in a pub

pany can easily spend more than E1500
per month on, say, six hall-page ads. To
recoup that cost, you woukl r>eed lo sell

J

\

i

brewed in

1

"Then there are hidden costs like rent,
rates, eledrictty and telephone. Finally

a kitchen

1

there is kit. We have hvo ZX81s, two

David Kelly talks to David

Jl'^'^^l

I

reconaers. We bum them up Ifke they're
going out of fashion — you have got to

Paterson, a founding

■

partner of Silversoft.

I

"So far we haven't begun to consJder

David Paterson is a voluble Glaswegian

profit.

wtm a wrisl walch Ihal plays Scotland the

"At any lime we have a considerable

Brave. Ha is also one ol the partnerB in the

investment in tapes and, in a market that

sotlwarB company, Silversoft.

changes aS quickly as this one, it Is quite

After leaving the University ol Strath-

easy to burn your fingers. When the

dyde t\e worked firsi lor a shipyard and

Spednim came out all our ZX81 atock

died.-

The Silversoft venture began as a hob-

Drop-out

by, "A buddy and 1 ware sitting in a pub."

The games that Silversoft now pnjduce

he explained, "thinking we musi get a

compirter and trying to work out how lo pay

for H. So we thought we'd write some
programs for the ZX81 '
TTiis was in the summer of 1 9B1 . "Some

sell — people always go for the devil Ihey
know. "We had a great game called
Drop-ou(. " said David, "and it did just that

3flvW PalB'son

o( the sotlware at that time was abysmal

and we thought we might be able to do

have all got the same problems. Our single

Now Ihal Atan are beginning to take

better, ■■

biggest worry is piracy. There is not a lo

action over alleged copyright inlringo-

The Hrst game they wrote was a 16K

you can do about it either — apart from

ments. sotlware companies may be forced

version of Slar Trek. "The big day came

keeping your eyes open. It is particularly

to produce more material based on th«r

We made the tapes, placed the adverts

annoying to look in the classified ads and

own original ideas. "If that happens," says

and sat back biting our nails, waiting lo see

see the program you spent six weel<s

David, "marketing will become the big

what would happen.

wnling being sold under a new name a

problem.

"And then the money started rolling in

half the price.

"The law in this area is very contused.

— WB were staggered by the response '

■Recently we have been noticing the

We even had one guy who said we

They recovered the cost of their advertis-

effect ol software libraries. They buy ou

ripped'Off his program by using Ihe com-

ing in the first week.

apes and then rent them out. All perfectly

mands Back. Forward, Left and Right.

"At first we recorded all the tapes in my

egal, but, in the end, the user loses out

What are we supposed to use — Retreat,

kitchen at home. 1 was working all through

What is the point in trying lo write a good

Advance, Port and Starboard?

Ihe night knocking the things out and then

program only to have it bought by the

"Vou have to accept that the copyrighl

doing s ful[-lime job in the daytime. We

brartes and loaned out? "

soon realised that the tapes would have to

Another major concern at the moment Is

Ihal It is OK providing the program is not

be manufactured professionally. 1 was

he prolileralion of machines. "All the main

an exact copy — it is the nature ol the

down to six and a half stone and couldn't

electronics companies are jumping on the

industry.

goon."

"There are lots ol different versions ol

Slversoft had 500 tapes made. The

often with no software back-up. A machine

tapes sold quicldy and the business has

never looked back

^Dst software companies will not have Ihe

ours are some of the superior progranw."

The company specialises in games

esources to cope with all these new

tapes lor the home consumer. David does

micros.

not think that there is a business market for
Ihe ZX machines and thinks most utility

■■Everyone thinks there are big profits to
be made in software — one magazine

What's happening

programs are a waste of lime. "Theydont

do anything you couldn't do Quicker on a

costs 22p to produce a tape. This just isn'

Thaitiei Valley ZX81 and Spectrum

piece of paper. That's why we make

User Group is being formed 10 cover

games — besides, it is fun."

■■Suppose the pnce of the cassette is CS

Slough, Reading. Windsor and Bracknell,

Davkl reckons there are three types of

Post and packing — about 40p — and VAT

Those inie rested should contact Richard

— 7Sp — coma ofl first The tape probably

Shepherd, 22 Green Leys, Maidenhead,

costs 60p to produce, including the cost o

Berkshire [Tel. 0628 21 107)

amateurs out lo spread Ihe word about

he insert and Inslmctions. And one can

computers, and egotislic technocrats who

expect to pay 20-25 percent royalties —

think it Is tiasny.

say El .35.

"I'll let you guess which 1 think 1 am." he

"That only leaves £2. From that comes

Contact Mrs K Bacon, 26 Mays Road,

grinned.

handling charges and advertising. A com

Wokingham. Berks (Tel: 0734 792569),

SSEPTEMBERIiBa

11

Reviews

Peter Qerrard takes a
comprehensive look at ttie
Commodore 64.

■ n appearance ihe Commodore 64 is very

sHohtly layered keyboard seen on the new

Vice. The lour funclion keys are also there.

Similarly, Ihe by-now familiar and ofl-

Imitated Pel graphics symbols are all

Most micros thai have been announced
over Iha last lew months, and there have
been many newcomers on the scene
lately, have been remarkably similar in
perJormance and price. No new outstand-
ing features have emerged in any ot them.
Even the Speclrum. subject o( sjch furore
around the Induslry when It first appeared.
has now lost some of rts Initial glamour.

The Commodore 64 has a number of
capabilities that maKe it stand out. but In
the long njn the deciding factor will be the
price. The reason why the ZX81 did so well
was its extremely low cost.

Commodore will be pncing the 64 at
around £299 plus VAT, maKirig a total
ol E350. This compares with a pnce of
£199 plus VAT for Commodore's Vic20,

No computer, other than the BBC micro,
has atlerrpted to come to grips with
musical synthesis on a big scale. Even on
the BBC machine, envelope shaping is not
the easiest of tasks. Admittedly you could
pay £15000 and acquire an amazing
purpose-built machine, but the home mar-
ket has been lacking such features, until

The VIC20 started the trend, with three
voices and a white noise generator. Clive
Sinclair look a step backward with the
Spectrum's Be^, but the Commodore 64
redresses the balance.

Inside the 64 is a chip known affec-
tionately as Sid (Sound Ir^terface Device?).
It is this chip that controls all sound output

able powers. Basically, you have control
over three independer^t voices, each of
wtiich has the following capabilities:

1) A nine octave range from 0.059Hz to
3.9Hz, in steps ot 0.059Hz.

2) Four different wavefonns (sawtooth,
triangle, variable pulse and noise).

3) Amplitude modulation and ring moOula-

4) Programmable addressable envelope
getierator.

5) Oscillator synchronisation.

There is a programmable filter, indi-
vidually selectable for each voice, and. as
on the Vic20, volume control from within
the software!

Will you sti
me now I'm

looks very good, control ot the sound is
guile easy. Certainly tnje synthesis is not
at all difficult You will soon have Ihe
living-room reverberating to the Branden-
burg Concerto, or Goody-Goody Two
Shoes for mat matter.

You can achieve very close api
tion to the timbre of a whole

be played at once, I suspect that I
be too long before Commodore, or some-
one else, comes out with a superb piece i
software to facilitate the production i
musical pieces. Our News Clesk will keep
you informed of any developments
Most micros coming on to the
make great play aCiout their graphit

from wllhin a Basic

I, both ir

add-on packages to enhance existing fea-

counts. The Commodore 64 has an im-
pressive performance in this lield.

Full resolution Is 320 by 200 pixels,
using a 40 column by 25 row screen. Thus
teletext is now at your command, providing
someone brings out the appropnate inter-

aid of data St

program. Y

matrii gnd ot 24 by 2i pixels. The charac-

On any given horizontal line you can
have up to eight sprites displayed. But. by
careful use of the interrupt capabilities of
trie video controller, you can have as many
as 256 spntes displayed simultaneously

Quite superb graphical displays can be
produced. To list just some of the capabili-
ties of the video controller. positionir>g of a
sprite is done by specifying an X — Y
regester, there are routines for expanding
sprites and filling in the background.
routines for collision detection, and so on
No longer need Tempest be restricted to

can be displayed per B x 8 pixel
I half resolution |160 x 200), you

per 8 X 4 pixel area.

it was impossible lo

Comnrotforo Co/rrputw S}jow, June 3-5
POPULAR COMPUTING WEEKLY

Reviews

II love
64?

pul the 64 through lis full paces. Cut we did
discover thai it can support a large number
of peripheral devlceB. With cassetfe inter-
face, serial Interface and B-bil parallel user
ports on board, this is hardly surprising. In
addition, if has merrKiry expansion and
cartridge ports, and is capable of support-
ing two joysticlis and four paddles. It can
also handle any of the existing Vic
peripherals.

Even n^ore exciting, the 64 can run any
software written for any other 40 column
Commodore rruchine. This is done quite
Ingeniously, By allering the memo/y map-
ping system.

The 64 has 20K of Rom on board,
including BK Basic and 6K Kemal as in the
Vic, and 64K of Ram, Of this Ram, 40K <s
directly useable from Basic, with the lop
24K being accessed from within the
machine code. Even if you know no1hli>g
about machine code, 40K ts sufficient

However, the 64 does have one major
failing. Why. oh why, does it still have
Basic 2.0 on txiard?

Basic 4 has been around tor quite some
time now, and Basic 5 has been nimoured
tor almost as long. So why on eahh stck to
an old, outdated version of the language?
Admittedly, it is ivot going to make any
difference for a lot of applications, but I
thought we had said goodbye to gartoage
collection long ago. Oh well, we must
assume Commodore has its reasons.

Summary

The 6502 has been and gone. We are left
with its offspring to provide us with a quite
superb machine. Despite my one major
grievance over Basic 2, I have no real

An outstanding feature of the 64 is that it
can accept a second processor (eg a ZBO),
which allows you lo run CP'M-bas»d soff-

SoTtware advantage

There IS a vast array ot programs tor
Pet wntien in Basic. Now that we can
gain access to CP/m software as well
number of packages already in exisi
lor the Commodore 64 is enormous,
will give it significant advantages

2 SePTEtilBER 19B2

extras you gel more than make up for Ihls.
The 64 already has a rich gnsund-base
of software. It is easy to use for anyone
remotely familiar with Commodore's own
implementation of Basic, and the new
facilities are all straightforward enough.
The documwilation is adequate, and may

We were onginally told to expect a
delivery dale of January 1963, but it looks
like Commodore is mateng great efforts to
bring this forward C)y a few rnonths.

ZX-6alaxlain

Artie Computing, 396 Jt
Avenue. Hull.
ZX81. 4K. cassene.

minutes and njns automatically.

After the title and copyright message
appear, there follows a description of th"

It starts after pressing any Key, upt
which an a^ay of four rows of eig
Galaxians appear, along with your bas
The Galaxians each score 10 points in D
convoy, and 20 when Ihey dive. Unlike If
arcade version there is only one type of
Galaxian, represented by the letter V v
in convoy, or by three pixels when diving.
Your base is formed fmm several pixels, it
is moved by pressing 5 and 6 and fires.

The graphics are adequate but crude
and there appears to be no relalionship
between your score and the speed a
treouency of the diving aliens. The 'cc
Ilnuous status report' refen^d to on t
cassette inlay is jusi a Oox displaying tlie
score, hi-score, base count and Instruc-
tions. This takes up most of the righl-hi
quarter of the screen and would be be
dispensed with and replaced by m
iniaginative graphics.

Each player is given throe bases. When
hit by a Galaxian missile, the base disinte-
grates in a suitably graphic explosion,

Ttio lop scorer can input six letters oi
numbers of his choice, enabling him tc
satisfy his desire for temporary immortality.

The game is also available from W K
Smith, paired with a program called Sword
ot Peace, pnce E4.9S.

Sword of Peace is a lext-only adve
game, written in Basic and is extremely
slow, even in the Fasf mode.

which you can destroy evil monsters,
time you cast a spell, or a spell- is
against you, a certain amount of enei
lost. If your energy decreases below

Summary

ZJtGalaxians is smooth-running and diffi-
cult, despite faults. One would be '""""'
pressed lo describe it as imaginative,
though.

Sword of Peace is interesting for five or
six garrws but, with its lack of speed arKi

although it has novelty value.

The decision whether to buy one game

for E3.95 or two games for C4.9S is yours.

AE

Open Forum

Open Forum is for you to publish your programs and ideas.

It is important that your programs are bug free before you send them in. We cannot test alt of them.

Contributions should be sent to: Popular Computing Weekly, Hobhouse Court,

19 Whitcomb Street, London WC2H 7HF.

How to conMbute

Binary

ie edilor goes through ill
IB thai you »«nd to Open
lertoflnd the Program ot
the Week,
The author of that program will quaitfy
for DOUBLE the uaual tM wa pay for
pubilahed programa,
{The uaual fee is £10.)
Presentation hlnt»
Programa which are moat likely to be ^„
considered lor the Program of ttie Week 2d key

on Spectnam
For ZXai and Spedrum use's tnis prog-
ram, which gives the binary and hexade-

should be useful for both giapliics and m.'c

In the Spectrum mar^ual, chapter 14
holds a program for ir putting your own
graphics, requiring a Bin input. "
though, enter the decimal equivalent, ini
keystrokes per entry, a total
es per use' character.

Putting
and delating the input on line 30 wi
look up table. The resulting error o
screen full, may bo answered *ilh Conf

will be computer printed and
accompanied by a cassette.

The program will t>e weil documents
the documentation being typed with
double spacing between each line,
Ttw documentation should start with a Alternatively replacing the Pi
general description of the program and with Lpnrirwilt give the complete

then give some detail of how the

program haa been constructed and c'

its special features.

LIstlnga taken from a ZX Printer shoul

be cut Into convenient lengths and

carefully stuck down on to white paps

avoiding any creasing.

Please enclose a stamped,

self-add reaaed envelope.

Design of program:
1 '5 Sets up variables
10 Gosubs 300 to set up coli

80-200 Checks and acts If an
being pressed.

210-227 Checks more keys ai
change tti

Vanabies used:

on Spectrum
This program enables the ZX Spectrum
to be able to draw a picture of his own
design on the 256-1 75 pixels available lo

le controls are as follows
S: Clears the whole screen.
OWE

screen In direction Z C of key being
pressed In relation to the S key
I* Pressing this key makes the computer
jsk you for the radius of a circle around 1He

U This key when pressed allows you to
ige the colours of Border. Paper. Ir\k
while still mnning the program.
O: Allows you to move the purser around
without leaving a trail.
I: This key returns the cursei to normal

a trail.

COMPUnNO WEEKLY

,r-

upen f oruin

When this is run, a set ol concentric do not affect Ihe scroll right routine.

Fine Scrolls

circles are drawn, which then scroll lo the Compare these routines with the usual
right and off the screen. Replacing the Usr scrolling on the Speclrum. It is obvious at a
call by 2379B will make them scroll to the glance Ihal these are more elegant: what

on Speclrum

The Fine scrolls program is really a pair ol

eft. may not be so obvious is that tliey provide

machine code roulines Ihal can be used to
great etfeci m a Sas« program. Thay will

11 is possible to scroll one third ol the
screen at a lime. Here is a table ol Ihe

more power over your screen.

each scroll the whole, or part, ot Ihe screen

'■"I'yS^.=....... = = .z^.iz = ^,» =

lo either led or right.

■=ii'?5&S.«V« TO ^,^7= SE«D

To scroll to the nght. Randomize usr

; aS°f|«^i;»?i^Tg S3B«. «EBI>

23760 Is used, and Ihis will move the

urnoiilaia loea IDOI zaoa 2002

whole screen lo tHe right by one high
resolution pixel. Randomize usr 23796 will

mBecftanged. lismS IMm 1 lieinS lUime
icfoll 100 Ihira. 64 7! S4 7!

ill! SS ii,!tl!ii*i§=a^i»"

do the same, bgl moving it ail to the lelt.

sciDHiTvidaie third. 7? 9) 72 aa

IP SS" "'"^'^'^''-"^

1

When entering the program, make sure

ScroH io»e. third an 8fl 80 Ba

i%\l |K SCRO^ L=FT

t'

there are 32 characters after each Hem in

i^lii^ir^c'w'nK Km""

ISSI s;s is-,?^6nsi's§-.??4"i"

\

tines 1 and 2. Run the program, then

jifl ^sil.;Pii*l^ia?siS'""

delete lines 10 to 5004. Add these lines as

You can arrange this so thai the two

a demonstration:

outines work on different parts ol the

l||l I rlNC >^ROLLS

:|gz;zz^;r

screen, as Ihe two data changes in lines

'^" " Fine ScKrflB

1000 and 1002 do not affecl the scroll left
loutlno, and Ihe changes in 2000 and 2002

by Bill Longley

Road Raco

h tll°Hitr

5 BBND

on ZX81

This is a game lor the ZX81 with at least
SK of memory. The game incorporates

graphics. The listing is given in two parts
— the Sasic and the machine code.

6 CL5
H POKE 1641S,B

^^^^^^^^^^^^Hi^g^i^

To enter the m.c first type in line 1 as a
Rem statement oi 49 'Xs. Then type as a
direct command Poke 16510, 0. This

13 POKE I&AIB.S

makes the Rem line 0. Now enter the rrvc

y^uuuuuouuuL"juuOwu";nT r,ii;-M|

loading program given and enter the code.

4.B NEXT I

Delete lines 9000 onwards and enter the

5B PRINT AT a , B ; "uuvyyuu-jw WW

BasK program.

uvy yuuuuuuuuuuwuuw"

This IS a road-race type game, you are
Onving Ihe S on the track and can control

J iP.sl??;

its movement left or right with keys 5 and

a si's''^ ii':i::-T^'

must avoid. It you hit another car or go oti
the track you crash very spectacularly.

'^t 3i?.S!!':x,'^!!5e'?SIS*IS?S'!l

Your score and the high score is display-
ed. The display uses all 24 lines and is

li fellNj'iT'iJ.X;--,--

totally tlickerlree.

~ • •i^:z ™'" "" " '•"

Tine program uses two machine code

routines. The first, from 16514 to 16543, is

P LET G=INT IRHDtB*3!

a very simple routine which scrolls Itie

a LET 0=1

whde display down one line. This is used

i fqr'-f" TO^G "^^ ""^

lo create the moving MoOt. The second.

2 LET B=USR 16514-

Irom 16544 to 1 6562, inverts the video and

1 „i41°!j-i;*r:..»-^

Is used to create the spectacular crash.

Parts ot the Basic program are re-
peated, once lor straights, and once lor

'isi IF PEEK 'Pffgg^|g|^*iil5'^fi

comers. 1 decided lo use this method

55S LET TI=TI*1 ,

tended lo slow down the speed ol the

IIS s?=g!;o?i.'?Ag(, i»..^ -T i,»

game.

"Ki-h(,;?v .

PngrHinolu:

see GOTO lea , „ .. ■ ■• ■ ftT ii

UneD: Machine (oOe.

leeo pRit^ n^ le. -•-•-, . , . h.

iSasVoRV^iJojl^^

IJHB 1 w D««e whether a oirw

till hl^T^F^^

Urn 141 ChecHoi crash

Una 170: PsOds whgihar u Mplay cppoiiBntB an

MSmM^^^^'^"

(INV S).

Une SIO. DBtMa diracOon ol qjivb

ii1% iF^'iNKkvi^::^,. ^'i^i;^ s^jg ^

-?' i^T^"^'--' wn-xiw

Z SEPTEMBER IBM

IS

-Open Fonun-

Block Graph

ip low ot the keyboard .

C: nurrljer o( columns.
0(C): siores tne heiglil ol eai
T:For-ftte«variablB, counisl
CCfT): stores the colour ot ei

Renumlwr

on ZX81
lavejusllyped a great program inloyourcomc
1 Id send il off to a magazine. You type Uisi
<r the line numbers go in odd jumps and steps.
_ w you have no need to wo^ — just add lines 9000 to 901
to your program, type Run 9000. key In the step and start for th
imbering, wait a bit, and your program will be renumljered.

IS

5 P0KE36879,S:pRINT'*h.T

18 PRINT"!(BLOCK Gt- PH PROGRRfli

2e .^RINT")(NO. OF COLUMNS "

30 INPUT C

40 DIMHCtC)

58 PRINT'-UHflT 130 VOU WANT TO "

60 PRINT"CfiLL IT"

70 INPUT m*

75 DIM0<C3 F0RT=1 TO C

88 PRINT'THOi'i fIBNV BLOCKS HIGH"

90 PRINT"DO VOU WRNT THE "JT.: "COLUfIN

TO BE. "
100 INPUT QCT>
110 NEXT T
120 DIMCC(C)
130 FORT-1 i } C

14t PRINT":UHRT COLOUR DO VOU "
150 PRINT"WHNT THE M; "COLUMN"
160 PRINT"TO BE"

170 IHPUT cca;

175 CC<T)-CC(TJ-1

160 NEXT T

990 PRINT"W;NI1«

1000 FOR R ■ 1 TO 18

1010 POKE 7681+FW22,106

1820 POKE 38401+F)«22.1

1030 NEXT fl

1040 FOR fi - 1 TO 18

1050 POKE SeSS-' .115

106fc =OKE 39819+0.1

1078 NEXT fl

1075 N-N*l

10B0 FOR V«0TOO<N)

1090 POKE 8079+<H-l)-<VM2J,16a

1100 POKE 38798+<N-l)-CV«22>,CC(H)

1110 NEXT V

1120 IF "^^C THENie?^^^^^^

23456709111111111"

1140 PRIiJ ''inBDfliniBIWmilWCTIM^^
mniMiD 12345675"

1150 FORR-1TO15000:NEXT

1160 pRiNT": i rti i rr in nnNT tc m

ANOTHER ?"
1170 GJTR*;IFB«-""THEN1170
11S0 IFfl*-"V"THEN RUN
1198 PRI!JT"GOODBVE."

■■STEP'?, ST nf

» LET l.=L*S
L ODTO 900*

by Chris Callander

POPUU^R COMPUTING WEEKLY

Open Fonun

Equations

TMe progra

n will filinlolK quite ea

machine code call lo

scroll loutine.

s part of 3 punt slalemer

good wtiole sc

reen display is achieved

Potypen

on Vic-SO

This is a poiyphonic slylophone progr
using the Vic iigW pen. Poirl the pen i
posllion along one of Ihe '
lines. Touching Ihe sensors iimidms mo
tone, ttiowing the pen hori/ontaliy changes

HR* (U5R S + U5R S) , ■■SOLUTIONS TO
piX**2tBX+C UHERe-;CHR( (U5R 5 + U£.

R s);TRB pitPi; ■•R = ■■;

30 INPUT R

4.0 PRINT fliCMRt (USR 5*UBn 5J j
TAB PIsPI; ^'B = ";
SO I^4PUT B

6G> PRINT B;CMR* (U5R S+USR SJ ,
TRB PI*PIi "C = ■';
70 INPUT C

30 PRINT C, CHRt ( U5R S +-U5R 53 J
30 LET X=BftB-d.*R*0
100 IF X<0 THEN GOTO 130^ ,_„_
lia PRINT ■■ORE; X = '■ ; ( -B* (SOR
X> ) ^ OtR) ; CMR« <U5R 5+USR S),^^OF
X = ■■;(-B-(50R X)l/(H*nJ
120 GOTO 20

130 PRINT "ORE NOT RERL . "
14.0 GOTO E0 _

150 5ByE ■■CURDRRTICS-
160 RUN

SOLUTIONS TO fl:
R = 1

:*f2+BX+C UHERE

RRE,
OR.

.236063

SOLUTIONS TO RX**2+BX+C UHERE

5 REN POLVPEN BV ft.BFiRTON.

10 DEFFHXCX)=INTC(PEEK(36870)-43)/d)

20 PRIHT-T

38 Sl3368?4 ■■ S2-36875 ■ S3-36876 ■ S4=36£;

50 PR INT "■WBMMMP ITCHES"

€0 PRINT"mM I ! II II I II II I II I M M"

62 PRINT"«»^ICES.

63 PRINT'-f«aMaTBi-Sl

64 PRINT "fliaaTa-S2 '

65 PRIMT"aBMa't*-S3

66 PRINT "iwnaiai-S'i ■

67 PRINT"iaat»Wi"rt'«*A'rfV.^rt'fWi'W.'

63 PRINT "nWTMKILL TONE UITH FEN

RND R KEV IN THIS TAB"
70 P0KEW,4

75 uniT37137,16

76 lFFNV<V>=iaTHENP=31

77 IFFNVCy)=13THENP'=S2
7a IFFN'V<V) = ISTHENP='33
79 IFFNV<V)=>ISTHENP=>34

31 IFFNXCX>»3THENP0KEP- 133

32 IFFNX(X)=4THEWP0KEP.-147
S4 IFFNKCX3=5THajP0KEP,159

iieFFNV(V) = INT(CPeEKi.3687i;-32)-'4>

■7 -7=36373

36 IFFNX<X)=6THENP0KEP,163

38 IFFNX<>.)-7THENP0KEP.175

■" 30 IFFNXC)O-8THeNP0KES1.193

92 IFFNX':X)=STHENP0KEP.13I
94 IFFN>«X)=ieiTHENP0^:eP,135
96 IFFN>^'■X)=^ThENPOKEP..^01

93 IFFW^:;Xi=12THENPCKEP.207
lae IFFh'XfX)=13TriENPOKEP.209
192 IFFNX«)=14THENP0KEP,215
194 IFFWX«)=15THENP0KEPj219
136 IFFNX';X; = 16THENPCKE?-223
103 IF"NX'CX)=17THENP0KEP-225
lie IFFNX(X)-13THENP0KEP.228
112 IFFNX<X)siSTHENP0KcP..231
203 QETS«'IF3»-""THEN75

228 POKE3L0-PQKES2,6:POKE33..

0- POKES*- 0;QOTO7S
RERDV.

-Open Forum

Sound Explorer

on BBC Micro
With all the sopriistication of
and Envelope commands on the BBC
Micro, it is no easy task to find the exact
pBrametera which give the sound you

This program lets you instantly hear the
arlad of ctianging any Sound or Envelope

1 HEK COPYKIGHT (C) JULY 19H2 by D. GUEST

10 NODE?

20 0^=5

30 PROCMEhU

40 ON EKKOE GOTO 680

50 DATA PUch, Duration, Time-Base, fREQ-VAR l.FREQ-VAK 2,

FUElj-VAW 3.FRE0-TIME 1
52 DATA FRE(j-TlhE 2..FUE0-TIME 3 .Attack , Decay , Sustain .

Keleaae.AniD-Level i
54 DATA Atnp-Level 2

5y HEM ** A SELECTION OF INITIAL VALUES FOR ENVELOPE
60 DATA 100,50,4,4.-8.-4.16,16,32,64,64,64,64,128,0
70 DU ESC14),E5(14)

80 FOU 12-0 TO 14:SEAD ESCIZ):NEXT

'JO FO(t n-0 TO 14:READ ESCli):NEXT

95 E^iAXi=255:EKIPi^— 127

100 PrtOCTEXT

110 *fXll.lO

120 *FX!2,5

130 »FX4.I

140 FOR C2-0 TO 14:PR0CPVAL:NEXT

150 PIUNT TA6C23,0h

160 Cl=0

170 REM

180 REPEAT

190 KV^FALSE

200 GS=GET

210 IF G3;-32 THEN PROCPLAV

22U IF GS-139 THLrt PBOCUP

230 IF G%'13B THEN PROCOOWti

240 IF G2=137 TttEN PROCINC

250 IF GS=136 then PUOCUEC

260 IF NV-THUE THEN PROCPVAL

270 UNTIL Gi-81

279 REM ** TYPING '(}' WILL END PROGRAM

280 *rai2.o
290 *ra4,o

300 CLS

310 END

320 REM

330 DEFPROCOP

340 IF C% > THEN Cl-CJ-l : VOOll

350 E.

360 DEFFHOCDOWN

370 IF C% < 14 THEN CS1=CK+1:VDU10

3B0 E.

390 DEFPROCINC

400 IF £2{Cl)<EMAXl THEN

£l{CJ)=E%(CS) + l:NV-'TRi)E
410 E.

420 DEFPiiOCDEC
430 IF E2(C%)>Emi'JX TilEN

E%(C%)-EK(Ci)-l:NV=TRUE
440 E.

450 DEFPROCPLAY

460 EKV. l.E%(2).EI(3),E!:(4),EK(5),E%(6),
EK(7).El(8),E3,X9).E%{10).Ei(in,E2(12),
ES<13),E%(14)

470 SOtINO S%.1.EJ;C0),E2(1)
479 KEM ** ONE SECOND DELAY BEFORE

FURTHER KEYSTKOKES ARE ACCEPTED
4SU TIME-0:KEPEAT UNTIL TIME=100
490 *FX15,1
500 E.

510 DEFPROCPVAL
520 PRI.IT TABC28.CS)Eft(CS);

:PRINT TAB(2a,C2};
530 E.

540 DEFPHOCTEXT
550 CLS

560 FOR 1=0 TO 1;PRINT CHR$131;

"SOUHD": NEXT
570 FOR 1=2 TO 14:P«IKT CHttS129;

"EKV.": NEXT
580 FOR 1=0 TO 14:PRINT

MH(25-LEN(ES(I),I);ES(I): NEXT
590 PRINT TAB(0.16);ChKS131 ;'''SOUMD ";

CHANS;",!, Pitch, Duration"
600 PRIi'JT TAB(0,17);CHRS12g;

"EHV. l,T,Fi,F2,F3.Tl,T2,T3"

POPULAR C0I.1PUTING WEEKLY

A_.. n.

wpeu X gnun

from previous paga

610 PKIiST TA6{10,18);CHRS129;"A,D.S,H,L1,LZ"

620 PK1.\T IAB(0,20);" Use ciirsor keys - up S daun to select,'

630 PHINT TAB(0.21);" side to side to vary values."

640 PKICT TA6(0.24);CllR5684;CHKSi,9D;

650 PRINT TAB(5,24):CHR¥ia7;"PREaB SPACE bAK TO HEAR SOUW

660 E.

670 REM EKKOH ROUTINE

680 '*ra4.U

690 ^FXIZ.Q

700 CLi

710 Hi;PORT:PRINT " at line ";KKL

72C Em

730 REM

740 DEPPROCHENU

750 PRIOT "SOlIhU EXPLORER

760 PRINT "This program allows you Co explore"

770 PfilOT "the SOUWD and ENVELOPE commands."'

780 PRINT "All current parameters are displayed"

790 PRINT "on the screen and any parameter can be"

800 PRINT "selected and varied up or dowm. "

810 PRIi^T "The current sound can be played at any"

320 PHIifT "time by pressing the space bar."

630 PRINT ""Select SOUND CHANNEL or i"

640 REPEAT :GK"GET: UNTIL G%-48 OR G^=49

3^9 REM ** BYTE 2 OF CHANNEL PAKAMETER IS SET TO

PLUSH PREVIOUS SOUND

S5U CHANS = "ol"+CilRSCl:S2-Gi-32

860 £.

A GREAT NEW COMPETITION WORTH £THOUSANDS TO THE WINNER

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Ihfllcan he mafketetJ commercially.

p

a--^-

3. AUtlcetfom Popular CompullngWfHikly Th»"lnnerwMIO«theaulhorwho.ubmils Its number oleqLallv gooda

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saretubmrtted

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Spectrum

V alot various contributors eJtplqre dlffarant ■■pacta ot the ZX Spectrum.

Patterns to
swim before
your eyes

John Scriven reveals a
hidden generator
for moir^ patterns.

finding your eiact screen location. Prog-
ram 3 stiows one way of achieving reason-
able results. The controls are as toHows:

The Scisen saving re

lu choose. 16384
3n ol the start and
rajmber of bytes
imply Save "x"

baHles you. Iry Program A. This fills

the hidden pallem generator shown in the
following program (Program 1 ) Due to the
way the Draw and Plot routines ooerate,
moirfi patterns are produced on pressing
the cursor Keys. The effects are similar to
me Interference patterns you see on nal
cudalns.

It Is possible to fill the screen cornpletely
but Program 2 will do that for you. The
pleasing thing for Sinclair owners Is that
the program can t>e squashed irto one line
— I recently saw a similar program on an
Apple II that was nearly SO lines long.

If you have experience ot a ZX31 . then
you must have come across many
'Sketchpad' programs. On a Spectrum, the
results ace much betlsr though, with
45,056 put positions, it can be ditficull

(Av^

-:zO

POPUlJlR COMPUTING WEEKLY

Sound & vision

Who will compare the show?

This progiam plays ihe song A IMe
Peace, winner nt Ihls year's Eumvislon
Song Contest, on the VicH>. The ptogram
uses two pan harmony and consists
almost entirely ot data statements.

Line 10 sets the volume lo five. You cen
adjust the vniume to suit your own tastes.
Line 20 simply atUws thetuneiobeplayed

wise, or more often ft you wish.

Una 40 Is a time deley lor the besic note
'alue. Lines 50 and 60 rJetennme whethar
he tune is being played lor the Ural or

R LITTLE PEACE

f? REM

t? PCKE35S7S..5.PRINT"n"
15 P!>IHTTflB(4V»M>MraHraR LITTLE PEACE"
18 PRIHT"»(EIH BISSCHEN FPIEDENV
28 FORR^ITOZ: RESTORE
38 REHBB, H ^ P0KE36875 , B ' PnKE36376 . H
4a FOPT=lTO20e:NEXT
58 IFB=1THEHNEXT:G0T039
m IFB-2THENENI)
78 GCT039

118 BflTfil?lr8.. 191 .0r8.0.195..8..281..0

128 I!RTn28I.223,581..223,9,223..281,223,2B7,223,2Ell,2I9.212.219
138 liaTR212.. 225, 212, 225, 8,225, 212.. 225, 212, 223, 212, 225, 215, 212, S19, 212
148 DRTP219, 219, 8, 219, 219, 219, 215, 219, 212, 219, 212, 219, 287, 281, 287, 201
158 CRTog, 215, 28}, 215, 201, 215, 191, 9,8, a, 191, 8, 195, 0,281, 8
168 ?RTR281, 223, 281, 223, 0,223, 201, 223, 287, 223, 297, 223, 281, 219, 212, 219
178 ilRTR212, 225,212, 225, 0,225, 212, 225,8, 225, 212, 225, 215,212, 219, 212
188 BRTfl219, 219, 8,219,219. 219, 215, 219,223,219,223, 219, 219,201, 215,201
190 I3flTfl215, 215, 215, 215, 215,215, 8,215, 3, 213.0,9, 0,0
208 BBTfle, 281, 175, 281, 8, 281, 175, 215, 201, 215, 201, 215, 201, 0,201, 215
^ir npTFlll7 212 147 21-> a 2ia 147.201,183,201,183,201,183,291,183,9
201 a 281 14-. 219, 183, 219, 183, 219, 183, 9,183, 219
^10 223 175.201,201,201,201,281,201,291,291,0
^a 1 ^Bl I'". 223, 281, 223, 281, 223, 281, 8. 201, 223
"" 13-. 287, 175, 297, 17!;207, 175, 8, 175, 287
<• 47,223,183,223,183,223,183,219,183,219
1= ' 1'5,215, 175,8, 175, 9, 147,9, !35,9

IP 8 1 8

1-5 8 9 191 17' 9' 193,281,191

-* ioTfl-)91 1°! 9 281 191 -^ - 191,8,9,215.191,219,195,223,281

9 TiQTqo T ^81 8 9 '^v^ 01 923 297,223,207,223.201,223,201

'8 ?PTB228 '"3 228 723 "'8 "3 228,223,228,223,2,8

3 SEPTEMBER 198a

-ip pR.'O 4
^"8 DflTP17

■• 8 BP'^R -

t-fll 147 i

HRTRl

^ IRTriio

It? T'oTPi ai

Programming

From little
Acorns grow
mighty . . .

Paul Howard explains how to
add 16K Ram to the BBC
model A.

Th& BBC microcompuler has proved to De
very popular and, although besel by daliv-
efy problems, many people are now estab-
llBhed users of mis machine. Bui, Ihe
various difficulties encountered in the eariy
manufactufB and dislribulion oT the com-
puter has meant that the majonty of the
machines in use are model As This has
led many users lo think about the possi-
Dilily of a "do-it-yourself" upgrade.

One ot the major drffarences between
trie two models is the extra 16K of random
access memory available on ine model 8.
TTie model B, with 32K. not only provides
space fof larger programs but also has
tour extra modes available. Only with the
full 32K can all the features of the graphics
be exploited, to give higher resolution and
more colour fad lilies.

The upgrading ot a model A to 32K is a
relatively easy task. Only eight extra inte-
grated circuits are needed and no solder-
ing IS required. Anyone wishing lo pedorm
the upgrade themselves should have no
difficiilly. provided thai a tew simple ir-
slructlons are followed and the computer
and components are handled carelully.
However, il should be remembered that
undertaking a "do-it-yourself" upgrade
may invalidate the six monlfi guarantee
provided by Acorn.

The components requi'ed are eight
48ieA dynamic Ram chips, available by
mail-order from many ol the larger electro-
nic component retailers {eg, Watford Elec-
ttontes, Technomalic Ltd) at a cost ol
approximately £2-£3 each.

These particular integrated circuits are
susceptible to the eltects ot sialic electri-
city. The pins should not be touched as this
could damage them permanently. The
worl< surface should be clean and dry, as
should your hands. It is also a good idea lo
leave the memory chips in Iheir protective
packaging until Ihey are required, and then

cover to the base. Two screws are located

The cover can now be replaced, making

sure Ihat the three LEDs are located

at the front — they are all labelled ■'Fix .

properly in their respective holes in Ihe

The top cover can now be litted away, but

be careful with the three red LED indica-

Reconnect the lead to Ihe TV and plug the

tors. These simply push through holes in

computer into the mains supply. When you

the plastic near the keyboard opening and

switch on the screen should display

could easily be broken if forced

The eight sockets for Ihe extra memory

are located in the front right hand corner of

Ihe main printed circuit board. These

sockets can be identified by the legend

M you do not get this response then

pnnted alongside each one and are num-

there is a problem somewhere. Check Ihat

bered IC6t , IC62, etc, up to and including

the new memory chips are pushed wel

icee. Simply insert the eight memory chips

into their sockets and that all the pins are

into these sockets, making sure that the

making good contact Try removing them

small D-shaped indentation in the end of

carelully and examining the pins — if they

each chip is facing towards the tear ot the

are bent then carefully straightei] and

computer (le pin number 1 to the rear).

re -insert them into the sockets, ensuring

similar to the ones already fixed in place.

that they are the correcl way round Also

Be very careful when pushing the chips in.

check Ihat the S25 connecting plug is

as the pins can easily bend, or miss the

making good contact between the centre

holes in the sockets.

and rear pins of the connector. If you stil

The only other alteration concerns a

have no joy when switching on then the

connecting link labelled "S2E". It is located

about tOcm from the rear of the computer.

aiould be returned to the retailer.

on the right hand side ol the pnnled circuit

If everything has worked successlully

board to the left of IC4S, Pull the blacK

you now have 32K of Ram available

plastk: plug from the connector and you

giving all the software features ol a mode

will see three pins in a line. Reconnect the

6. Any programs written tor a model B

which do not use any ol Ihe extra input

connector — it was previously across Ihe

output hardware, will now run in this

centre and front pins.

upgraded version ol a model A.

Prior to starting the upgrade, make

absolutely sure that the computer is dis-

connected Irom the mains supply — unplug

it. Also remove the TV and cassette leads

unfastening the four screws secunng the

bbC

POPUU\H COMPUTING WEEKLY

Peek & poke

Peak your problems to our address. Ian Beardsmors will poke back an answer.

HELP ME TO THE
RIGHT ADDHESS

Ql hKve hMl my 7.X8I for
about nine monllG. but
(Ound Ihil il wb Iud limiled
for mj purpom. Re«nll\. 1
|ht a VklD. Bui, nunv oT
pn^nuns I HriW for Ihf
ZXBI have a \a\ at Perk and
Pake slatementi.

lale. The screen localion of
7787 can be Poked on an
unexpanded Vic with no prob-
lem. On a ZX8I thai address is
pan of Ihe dollai sign charac-
lei. As this is pan of the
ZXHl's Rom. il certainly can-
be accessed by a Poke

ncludc Ihe smidl n

a IM nr
1 »Bnl lo change

Mill Hnd U vcr>

Ah is very difficult, il not
impossible, to list Ihe
compatible addresses belween
the ZX81 and [he Vic or the
Pel, The Vie can access up to
.. givmg a potent ial max-
m of 6553S addreraes. all
ofwhichcanbePEe/led-

^ thorougb breakdown of

of Nick

Han

the ^
page

book The Vic Revealed. If you
'ant a memory map of the
'et. then look at Besi of Ihe
VK Commodore Pel news-
impilalion of volumes
two. edited by Dave
Middleton. which has 27 pages
of Pel memory maps a< the
It. This Is available for
iO from CommmJoi

SOMEBODY GIVE
ME A SIGH

ZXSItohelpm

niLogy. whkh in-

volves many cnlculBtion.'i.

I wrole to Roger Elliot of
Star Life and got a very helpful
letter back. Unforlunately, I
do nol feel (hat my knowledge
of computing Is gnnd enough.
Is (here anylhing yi

bdp.
could 1

^ 1 feel thai you, bes,
develop your ZXNl

is of yc

Irological
typical program could include
(1) Sidereal time, GMT; (2) ST.
GMT + Eastetu lime zones:
(3) ST. GMT -I- Western t

; (*) F

f Mer-

. 19

Whitcomb Slreel, London
WC2,

The ZX manual gives quite
a good breakctown of Ihe ac-

comparativelv sinlple. For ej-
ample. Membol is 1M77 on a
ZX8] and 6543(5 on a Vic, But,
Ihe two dialecH of Basic aie
very often difGcult to trans-

2 SEPTEMBER 1962

m RETURN

Lines 2U lo 45 input and
print the lime of birth. Lines
SO and 60 make the first pan of

have a ZX81 wllh 16K
>m. I am working my
ough Ihe book 30 hour
Id am doing quite well.

vith a Goto 160 which will
irintoul the results.
This program assumes you

e I

signs after line 110 which be-
comes LET S3-S1-S2.

1 have used Louis Mac-
Neice's book Astrology as a

son of calculation on a ZX81.
or a Spectrum, do not forget
that il works in radians, not

one who can help you. Have
you cotisidered looking for a
local computer club? Alterna-
tively, you tnight find a visit to
your local library or an

with tl

ZX spectrum?

A Whatever your reason?
for learning machine
code, it is a useful laitgu^e Ic
know. The Zaks book is consi-
dered by many to be the bible
of Z80 programming, though
you should note that both the
Spectrum and the ZXSl u
the Z80a chip which is a mod-
ified version of the Z80.

micros, as will the mnemc
What does change is the way
all the signals into and oi ' '
the chip are inlerpreled.

A signal going into a chip al
point A will produce a re-
sponse at point B. It will al-
ways be the same response al
the same point. However,
where one micro might inler-

Refresh the Bam, another
computer might see it as part
of a Print command.

One note about the Rodney
Zaks book is that it is
expensive, Il might he adviv
able to go on youi library's i
doubt long wailing list for the
book. As an alternative, you
might try and get hold of a
copy of Nat Wordswonh^s Z80
Innniaian Handhaok which is
published by Scelbi.

BUT* STAR
M«PISO»

ends.

aiocBl

n HUT BE
IMCOBE

Ql^

have been wailing for

more about machine code.

If a microeompuler uses a
280 processor will It have Ihe
same mnemonics and heiadc-

I have s

a program to

use in astrology. Do you I
of any limilar. Bask f
rams, for the ZX817

A The only iwo prc^rams I
know of that might be of
any use are astronomy pro-
grams. One by Hclta-S' '
Software, of Fe.rys
Tookey Road. New Romney.
Kent, deals with planetary
palhs. The other, by Bug-
Byte. 9H/lD0The Albany. Old
Hali Street, Liverpool L3. i
called Constellation and wil
'draw a map of Ihe night sky fo
anywhere on the earth, for any
lime since ITOH.

Classified

CUT-PRICE COMPANIONS

LINSAC (PC)

4tK SPECmUK
3. jutfilicabon,

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mfiMiBlttortfQTSrrO Pte. MUr^B

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SPECTHUM SOFTWARE La

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Hflin sofhvara. cofTBcHy and Int

Conlpulflr Saltware, 68

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BBC MICRO

LET YOUR BBC :

Laadm \tS6FJ.

PROGRAM (XHERATORS

sPEcnwH aou. ocwewoiu

^ fair/isv '"^ Bl cbslxfa
mns irttatg antes ana EagUi.

hs iBnVly Omvt Q mMion graded 'Ri

POPULAR COMPUTING WEEKLY

POPULARr
JWEEKLY/'

BACK
NUMBERS

MAKE SURE OF A

REAL COLLECTORS' ITEM —

THE FULL SET OF PCW

We will mail any of the numbers you're missing

from Issue 1 to tfie latest — lor just 50p an

issue, including p & p.

(We have no more copies of Issue 2)

Send cheques' Postal Orders to:

Back Numbers

Popular Computing Weekly

Hobhouse Court

19 Whitcomb Street

London

WC2 7HF

HE SAID

YOU COULDN'T DO IT

WEDIDIT

A revolution in teaching programming techniques.

Appreciate tfie real value of your computer.

READ ZXei HORIZON (with tape).

Learn to link COPY, MOVE and (WERGE.

No programmer should be without this book.

Contents:

Daiaciive File text

Billiards Ariimaled cyclist

Machine code orogrammet Load and Save
Call-bacK routine

Price £12

Cheques payable to J. tMNamsra'ZXBl .

Wb can acCBpS no responsiOilily for any illegal use at Ifiese

To urrGEVEBW WOLFKAMP

POSTBUS 7D2M
<l007Ka| AMSTERDAM — NETHERLANDS
TELEPHONE: AMSTERDAM 020278931

CLASSIFIED ADVERTISING RATES:

Here's my classified ad.

(Please write your copy in capital letters on tfie lines below.)

Pua» a>nm» on a »p.rBl« s»»< ol pap« |

2 SEPTEMBER 1982

Competitions

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'.. .^'

An exciting new Commodore
- peripheral

Own or use a Pet or a Vic?

Fed up with being ignored by all the
traditional monlhlv magaiines?

Fed up with listings, which are too simple
or simply do network?

You need Commodore Computing, the nev
monthly maga?ine. Commodore Computing
is published by Nick Hampshire, author of
The Pet Revealed, Pet Graphics. A Library of
Subroutines and The Vic Revealed.

Each issue is packed with advanced

advice on how to make the most of your
computer, whether you use a Pet or a Vic.

Each issue covers a host of application
-software, hardware, machine code, game
business use -whatever it is you'll find ilir
Cornmodore Computing.

H you want to learn more about your
computer, take out a subscription to
Commodore Computing.

That's the only way to get it, and get it
straight.

Send £12.50 for 1 year's subscription (10 iss

»s)t(

Commodore Computing.
Magsub, Oakfield House, Perrymount Road, Haywards Heath, Sussex RH16 3DH

New From Fuller
FD Syitem Sor the

ZX SPECTRUM

£39.95

- £2.50 p & p.

Professional Keyboard & Case —

ToughA BS. Plastic
the Power Supply
Our own Power =

jrKeyboi

theSpectru

ailable>9 voiis DC
ir 2'40v AC at £5.95 + 80p. p & p
The Keyboard has 43 keys with all the spectrum functions printed on
key switches have gold plated contacts and a guaranteed iile of U
INSTALLATION - Simply unscrew the ZX printed circuit board frorr
Into the FD case, plug in the keyboard and that's it No technical kn
required, ttie built unit is tested and comes with a money back gu;
Spectrum Keyboard and Case Kit £33.95

Our Mother Board tor the spectrum has 2 slots at £15.95 or 3 slots at
fixes inside the case p & p 80p

SPECTRUM SOUND AMPLIFIER £5.95+ SOp p & p.
Complete with leads, volume control and loud
speaker in tough ABS Plastic case measuring
5" X 3" K 1 " just plugs into your spectrum MIC
input
SPECTRUM PLUG PLANNER - £18.95 • £1.00 p & p

ithem.lhefuiltrawe

GUARANTEED 14 I

S DELIVERY Fl

Complete with 3 metres o1 cable, three 13

amp sockets for TV, Tape etc AND 9 voll

at 2 amp power supply with power jack to

f(l Spectrum or ZXBl

The ever popular FD42 Keyboard and case

for ZX81 £39.93 including VAT 4 Post

FDd2 as a kit £33.95 including VAT A Post

FD42 Built only £24.95 including VAT & Post

FD42 Keyboard Kit £18.95 including VAT S Post

U RECEIPT OF ORDER. OR CALLTOTHEZX CENTRE.

Mail to FULLER MICRO SYSTEMS,

The ZX Centre, Sweeting Street. Liverpool a. England. U.K.
Please Supply:-

Address

I

H

Q
to

s