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** SAVE MV1 - a Z80 c o m p u t e r
The MV1 computer kit uses the ubiquitous Nascom 1 Pcband the Z8Q C PU interfaces are included for television, printer and cassette 2K memory, Gemini power supply (drives up to 3 extra boards) Cherry full ASCII keyboard and Quantum Graphics are also
included. Available with either an ASCII version of the Nas-Sys 3 monitor, or a Tiny BASIC.
MV1 is expandable to Gemini BO-BUS specification.
M i c r o V a l u e p r i c e
£105 MicroValue's
' N a s c o m Spec ia l '
+VAT
SAVE ^ OVER £65
We've put together a microcomputer kit containing the Nascom 2, Nas-Sys 3. Graphics ROM. Bits & RC.'s programmers aid. Gemini 3 APSU, 16K RAM Board and mini motherboard. The result is a powerful micro using market proven boards and components.
RRP O V E R £ 4 0 5 +VAT
£ 3 4 0 VAT
SHARP MZ80K with Super G r a p h i c s
SAVE £200!
The 48K RAM System is offered at o rock bottom price with the Quantum Micros Hi Res Graphics which gives resolution down to a single dot a nd high res. plotting. Characters are user definable and the pixel characters actually join. Frve tree games packages are included too!
RRP £ 6 4 5 4 VAT M l c r o V a l u e p r t c e
£ 4 4 5
4 8 K M Z 8 0 K RRP £ 4 6 0 VAT M / i r M i c r o V a l u e p r i c e
(f£30 w o r t h o f a c c e s s o r i e s
F R E E w i t h e v e r y
v
Epson Printer M l c r o V a i u « p r t c e
E p s o n M X 8 0 T . £ 3 5 9 - VAT E p s o n M X 8 U F T 1 £ 3 9 9 „ VAT Epson MX8UFT2 £465 - VAT E p s o n M X 1 Q 0 . £ 5 7 5 . V A T
Buy one ol tne above Epsons from MicroValue ana we'll give you o Pack of rantoid paper, Interfacing Doc jmen t a nd Connecting Cora for Multiboard or Nascom. The accessories a.c worth £20 but you can have them absolutely f-Kcc
N a s c o m IMP + G r a p h i c s SAVE Only £ 1 9 9 + V A T £ 1 5 6
MicroValue has stashed the price of the 80cps 80coiur MPaot matrix printer And added imprint's high res graphic $ c a aouoie width character option. IMP has c w UAT
bt-direcfional pnnting a n a * " , ' friction/tractonfeed M.croVqlue price £ 1 9 9 SijDiec'toonlytimonllu waranty VAT
NASBUS C o m p a t i b l e DOUBLE DENSITY Disk S y s t e m -Avai lab le Ex Stock With hundreds in daily use the Gemini Disk system is now the standard for Nascom and Gemini Multiboard systems Single or twin drive configurations are available, giving 350K storage per drive. The CP/M 2.2 package supplied supports on-screen editing with either the normal Nascom or Gemini IVC screens, parallel or serial printers, and auto smgle-double density selection. An optional alternative to C P M is ovailablefor Nascom owners wishing to support existing software. Called POLYDOS 2 it includes an editor ond assembler and extends the Nascom BASIC to include disk commands
S i n g l e d r i v e s y s t e m ( G 8 0 9 , G 8 1 5 / 1 ) £ 4 5 0 VAT D o u b l e d r i v e s y s t e m ( G 8 0 9 , G 8 1 5 / 2 ) £ 6 7 5 VAT C P / M 2 , 2 p a c k a g e ( G 5 1 3 ) £ 100 * VAT
P o l y d o s 2 £ 9 0 * VAT
8 VOOK COMPUTER. PclSnUAHY 1982
MICRO.COM PUTERS
Shops N a t i o n w i d e Birmingham
19/21 Corporal ion Street. Birmingham, B2 4LP
Tel: 021 632 6303.
Manager Peler Stallard. 300 yards from Bullring Centre
Bristol 16/20 Penn Street, Bristol, 8S1 3AN. Tel. 0272 20421
Between Holiday Inn and C & A.
Chester The Forum, Northgale Street, Chester, CHI 2BZ
Tel: 0244 317667,
Manager Jeiemy Ashcroft. Next to the Town Hall.
Edinburgh 4 St. James Centre, Edinburgh, EH1 3SR. Tel: 031-556 6217.
Manager: Colin Draper.
East end of Prices Street, St. James Centre
Preston 1/4 Guildhall Arcade, Preston, PR1 1 HR
Tel: 0772 59264
Manager Jim Comisky. Directly under Guild Hall.
Manchester 12/14 St Mary's Gote, Market Street, Manchester, Ml 1 PX
Tel 061 832 6087.
Manager: Lesly Jacobs Corner of Deansgote. Manager: Lesty Jc
Glasg o w 22/24 West Nile Street, Glasgow, G7 2PF Tel: 041 -226 3349
Manager: David Livingstone.
Berween Buchannan Slreet ond Central Station
Sheffield 58 Leopold Street, Sheffield, SI 2GZ. Tel: 0742 75097)
Manager Justin Rowles. Top of the Moor, opposite Town Hall
Liverpool A p p l e II A t a r i 8 0 0 33 Dole Street, Liverpool, 12 2HF. Tel: 051-236 2828
Manager Mark Butler
8etween the Town Hall and Magistrates Courts.
London 42 Tottenham Court Road, London, W1 9RD.
Tel: 01-636 0845. Manager Vass Demo$thenis.
Official Orders ^ Q a r e welcome -with normal 30 days
credit extended to bono-fide commercial and government organisations.
Laskys. the reta i l d iv is ion o f ^ ^ tKp L a d b r o k e G r o u p o f C o m p o n i e s mmotrnmm
AT A ^ J M M M ^ M M / M M /
Thewoftcls bes' selling micro offers unmatched flexibility A t our speeml prices Apple II + 48K Nett 675 .00 Va' 1 0 1 2 5 Toiol 776.25 D>sk Drive Plus Coniro Iter [3 3)
Ne i r 3 7 5 0 0 V 0 t S 6 25 Toiol 431.25 Disk Dnve
N * t 2 9 5 0 0 Vot 44 25 Toiol: 339.25
Deservedly popular rhe MZ 80K comes wilh 48K of RAM. tv i l l in screen and eosiette. - superb value M l 80K Computer 4SK
Neil. 3 4 7 0 0 Vol 52 00 Total 399.00
A t a r i 4 0 0 Ideal for the home wilh excellent gomes ond educolion package-, This computer features co'our ond sound and is built tough la lost 400 16K Computer
Nett 300.00 Vat 45.00 Total 3 4 5 0 0 410 Tope Recorder
Nett 43 48 Vaf: 6 52 Totol 50 00
TVie big brother of the 40C shores all the star feotures and hos much mo'e os we 800 16K Computer
Nett: 5 6 0 8 ? Vai 8 4 ' 3 To'ol 6 4 5 0 0 8 1 0 Dak Drrve
Nett. 300 OC Va' 4 5 CO Total 3 4 5 0 0 822 Thermo' Pnnter
N C M 2 3 0 4 3 Vet 3 4 57 Total 2 6 5 00
H e w l e t t P a c k a r d H P 8 5 Scientific and reehn col o"Otestionals favour i h e H P 85 rhey ore b e f - g .oined b y increasing numbe'S of business arofess-enols. H P 35 Conpuier
Nerr 2 U 6 95 VAI 3 2 2 0 4 Total: 2 4 6 8 9 9 1 6 K M e m o r y M o d u l e
NBM 19d 88 VOT 29.23 Totol 224 ) 1 R O M D r a w e r
Netf 29 73 Vor 4 46 Tolol: 34 19
YOUR COMPUTER, FEBRUARY 1982 50
RESPONSE FRAME Do you have a problem? Your manual is incomprehensible or you just cannot get the hang of that programming trick you tried — whatever it is, Tim Hartnell will do his best to answer your queries. Please include only one question per letter and mark them "Response Frame". KEYBOARD FAULT • Over a period of about seven
months, my Acorn Atom has
deve l oped a f au l t wh i c h
produces double entries when
any of the keys are pressed. This
fault seems to be the result of
poor-quality contacts on the key-
board — a problem which seems
to be occurring increasingly
frequently. Acorn's solution was
to send me several new key
contacts to replace the old ones,
but I feel this is no solution to the
poor quality of the keyboard.
Could you direct me and others
in possibly the same situation to
any company which stocks a
suitable replacement keyboard?
I am quite prepared to make
alterations to the printcd-circuit
board and re-case my machine.
Andrew Taylor,
Headingley, Leeds.
Yov ARE not alone — the office
Acorn Atom tends to double-strike
the letter s, but has not yet shown a
tendency to do so with other letters.
Wc understand from Acorn that the
Atoms being dcspatchcd at present
have a much better ctuality keyboard,
based on the one for the BBC Micro-
computer. That, however, docs nor
help you. We cannot rccommcnd a
specific keyboard from a specific
supplier, but suggest any coded
keyboard is likely to prove suitable.
Hobbyist suppliers such as Maplin
or Henry's Radio have suitable
keyboards in stock. We surest that
before you go for this radical
solution, you rcplacc the keys
supplied by Acorn, and sec if a
change in your typing touch does
not diminish or completely remove
the double-strike problem.
PET LANGUAGE • I am looking for a computer
and it must cost, at most, £200. It
must also have more than IK
memory, and have the same
Basic as wc are learning at
school — wc use it on the
Commodore Pet. It must also he
able to load programs from
cassette. I f there is such a
computer , I would be very
grateful if you could tell me what
It is and how much it costs.
N Jones,
Stsansea.
THF. SIMPI.F. answer to your needs is
the Commodore Vic-20, which uses
Pet Basic, and loads and saves
reliably from the Commodore
cassette recorder. However, it will
not meet your cost criterion. It costs
around £185 to £195 for the
computer, with an extra £J5 to £40
for the special cassette recorder
which it demands. However, it may
well be worth paying the extra to
buy a computer which meets your
other needs. Otherwise, you niav like
to look at the ZX-81, which except
for certain programming demands —
such as the need for the word Let —
will work reasonably well on the
Basic you are learning. Ii costs
£69.95. The Acorn Atom, £120 to
£150, is a splendid computer for the
price, but suffers from using a very
non-standard version of' Basic.
QUIETER SHARP • Is it possible to control the
sound volume of the Sharp MZ-
80K by means of software? I f so.
can you please help and if not,
can you show me any other
method before the computer is
smashed by the neighbours?
Hassoud Am ire,
Geneiw, Switzerland.
WF. vi'F.RF. Ai.so appalled by the
volume level of the MZ-80K, and ;it
first attempted to solve the problem
by placing a book against the
speaker. There is, however, a
volume control in the MZ-80K,
although you need to unscrew four
bolts at the base to lili of! the cover.
You will have no trouble locating
this control once you remove the lid.
BOOKS ON BASIC • I have seen a number of
a d ve r t i s emen t s in Your
Computer for books wh ich
purport to teach a beginner to
p r og r am . I do not have a
computer as yet hut would like
to team to program — if such a
thing is possible — before I go
wild and spend a few hundred
pounds on a computer myself.
Can I learn to program without a
computer, and if I can, which
books would help me?
Arnold Gautvorih,
Cohoyn Bay, Ck-yd.
YF.S. YOU CAN learn to program
without a computer, but to do so is
as unsatisfying as "learning" to play
a musical instrument by just reading
a correspondence course on how to
play the piano. However, you can
certainly gain a head start in
programming, so when you finally
decide to buy a machine, you will
find ii easier to make progress. It is
difficult to recommend specific
books — there arc so many good
books on Basic programming. A few
which you may find useful are: Basic
from the ground up by David F.
S imon, Hayden; Making Basic ivork
for you by Claude J Dc Rossi,
Rcston; Beginning Basic by Paul M
Chirlian, Dilithium Press. One book
which we found particularly useful I
was Game playing tsiih Basic by
Donald D Spencer which, although
it does not attempt to teach Basic
from first principles, is capable of
doing so if you work methodically.
Once you have the basics under your
belt you may wish to look at The
Basic cookbook, by Ken Tracton,
published by Radio Shack and
available from most Tandy dealers.
ZX 81 PROBLEMS • C an you he lp w i th two
problems on my ZX-81? Having
experienced great delays and
frustrations over replacing a
faulty R A M , 1 am reluctant to
attempt to approach Sinclair
again. I have the vanishing
m e m o r y / v a n i s h i n g p r o g r a m
phenomenon. In my case, this is
a resu l t o f ed i t i ng in the
presence of a multi-dimensional
array. T he defect of the Gosub
slack is nut confined to bad
programming. With a databank
type of program, where a new
version has to be saved from
time (O time, surely the Gosub
stack accumulates every t ime,
and will eventually wreck the
program. I am having to keep
away from Gosubs at present
because of this. Am I right?
K H Sargent, Byflect, Surrey.
YIX" sot'ND AS if you have a crazy
ZX-81, or else you are simply mis-
interpreting what it is doing. We
have never encountered instabilities
due to size of arrays. The most likely
explanation for the memory dropout
is mains fluctuations which can be
solved by putting a 9V battery in
parallel across the power-supply
lines. Another possible cause is dirt
or moisture on ihe contacts. Clean
the contacts very gently with fine
emerv paper, then either put the
RAM pack on and leave it there for
ever, making sure it docs noi move
when you press a key, or — from
time to time — spray the contacts at
the back with the kind of moisture-
removing spray sold for hard-to-start
cars. The ZX-81 appears to do its
own house-cleaning on the address
which is left on the stack. Unlike
many other computers, you can
iump out of loops for ever without
the loop count clogging the works.
Why would you have a subroutine
which is not followed by a Return? If
you need a subroutine of this form,
use a Goto instead, with a variable
assigned iust before ihe Goto which
is, in effect, the return address. In
this way, the Goto can end with
another Goto taking you back to the
line after your original Goto.
TEACHER'S ADVICE • I am 12 years old, interested in
computers and have been saving
for some months to buy my own
machine. I had intended to buy a
S inc la i r ZX-81, which seems
very popular. When I told my
teacher of this, he explained that
the ZX-81 keyboard shows signs
of wear after some months of
constant use and suggested that I
consider buying another make of
computer. Unfortunately, other
machines are well beyond my
resources. I would be most
grateful if you could advise me
as to whether the ZX-81 has this
keyboard weakness.
Huw Uoteell,
Port Talbot, West Glamorgan.
YOUR TF.AOHER, we respectfully
suggesi, does not know what he is
talking about. Any keyboard
weakness lias never been mentioned
in mail to ihe National ZX-80 and
ZX-81 Users' Club, and we assure
you that if ihis were a weakness, we
would have known about it by now.
You should buy whichever com-
puter you want, and can afford,
because any computer is better than
none at all, and any computer will
help you to become computer
literate.
CHOICE IS YOURS • I am considering buying a
BBC Microcomputer which I
understand, uses a standard
form of Basic. Should I start
with a BBC machine, or perhaps
buy something cheaper first,
and then progress to the BBC
computer in due coursc?
Martin Wellwing,
Hampshire.
APART FROM the fact that demand
appears to be outstripping supply,
which could mean a considerable
wait before you receive your
machine, there is no reason —
assuming you can afford it — for not
buying a BBC or any other machine
you desire. The BBC Micro-
computer has a very flexible Basic,
very close to standard Microsoft,
which you will find easy to transfer
to other machines of your choice.
There are also a number of features
it has inherited from the Atom — the
Atom and the BBC machine are both
produced by Acorn Computer of
Cambridge. The features that the
two machines have in common
include the use of P. for Print, ? for
Peek and Poke — where the contcxt
defines which is which — and
abbreviations such as L. for List and
GOS for Gosub.
DOUBLE-SIZE R A M • I own a ZX-81 with a 16K
RAM . The pack is unreliable
and too of ten causes the
program to crash for no reason.
So I a m looking for some
a l t e r n a t i v e s . One o f the
a dve r t i s emen t s in Your
Computer claimed an expansion
module from 16K up to 128K.
However, to my knowledge, for
the Z-fiO CPU, the max imum
addressable capaci ty should
only be 64K. How can it be I28K?
C C Fung,
Koath, Cardiff.
THI-SE D E V I C E S use a paged
approach, where the memory avail-
able is switched by commands from
Ihe computer through the output
port. It is switched on to different
sections of external memory. jSffi
YOUR COMPUTER, FEBRUARY 1982 61
J R S S O F T W A R E 19 W A Y S I D E A V E N U E . W O R T H I N G , S U S S E X . B N 1 3 3 J U
T E L E P H O N E W O R T H I N G 65691 ( E v e n i n g s a n d W a « k « n d * o n l y )
2 X 8 1 - S L A L O M I 1 6 K R A M P A C K R E Q D . I S l a l o m events a l w a y s d r a w grea t c r o w d s to t h e ski resof ls a n d i h e T V . c o m u r a s are never far beh ind . N o w (he skier o n y o u r T V . sc reen d i rect ly u n d e r your c o n t r o l a n d his success in n e g o t i a t i n g the s la lom pests a n d ach iev ing a l»s l t ime relies entirety o n your skill w t h t h e Z X 8 I keys .
m^m @ d
m m
Z X 8 1 B L A C K H O L E S I 1 6 K R A M P A C K R E Q D I Y o u r starship is in a n u n k n o w n ga laxy cons is t ing ent ire ly .if b lack ho les w h i c h cont inua l ly th rea ten t o s w a l l o w y o u . Y o u r skill a t t h e c o n t r o l a n d y o u r abil i ty t o took a n d th ink m a n y m o v e s a h e a d is t h e on ly th ing tnat s t a n d s b e t w e e n y o u a n d dest ruc t ion . H o w long c a n you s u r v i v e 7
B O T H p r o g r a m s o n o n e c a s s e t t e £ 4 . 9 5
N E W - A n E S S E N T I A L a d d i t i o n t o y o u r I K R A M Z X 8 1 (Or Z X 8 0 6 K R O M > C S S D O a -vnt ten b y P A U L H O L M E S )
Prov ides the fo l low ing add i t iona l facilit ies: Line r e n u m b o t - you state s tar t ing n u m b e r a n d i n c r e m e n t va lue . S e a r c h a n d rep lace c h a n g e s every o c c u r e n c e of a charac te r as yoo reaui re . Free space tens y o u h o w m a n y f ree by tes y o u h a v e left . S P E C I A L G R A P H I C S R O U T I N E S
H y p e r yraphic& m o d e - graphics never seen o n a Z X 8 I be fore . O p e n — instant ly sets u p as m a n y e m p t y print l ines as y o u requi te . Fill - u s e d in c o n j u n c t i o n w i t h O P E N fills your screen instant ly w i t h y o u r speci f ied character . Reverse — c h a n g e s e a c h charac te r o n your screen to its inverse v ideo T A P E R O U T I N E - providus a system W A I T condition u n M a sgnal s received in the casset te ear jack — m a n y uses ' Al l these rout ines are w r i t t e n in m a c h i n e c o d e a n d togo lher take u p onty 164 B Y T E S of y o u r prec ious R A M - e n incred ib le a c h i e v e m e n t ! ! T h e pr ice i i incredib le too! O N L Y £ 3 . 9 6 for casset te , inc lud ing F U L L inst ruct ions a n d e x a m p l e p r o g r a m s . A L S O avai lable 16K vers ion O N L Y £ 4 . 9 6 w h i c h includes all t h e a b o v e P L U S : G O T O ' s a n d G O S U S ' s i n c l u d e d in lino r e n u m b e r . S e a r c h for a n d list e v e r y l ine c o n t a i n i n g spec i f ied charac te r .
Z X 8 0 - P R O G R A M M A B L E M O V I N G D I S P L A Y ( 4 K - R O M only ) N O W O N L Y € 3 96 Casset te w i t h I K , 2 K versions a n d 3 e x a m p l e p r o g r a m s plus F U L L d o c u m e n t a t i o n
16K R A M p a c k black case, ful ly t e s t e d a n d g u a t a n t e e d ip iease a l low days for d d i v e r y l Full refund if not delighted.
£35 OVERSEAS CUSTOMERS PLEASE NOTE
rrusi be m x l t n Sw-ling by IflterntKvijI M o n o Ordu 'SvoieOW m r o u ' b i i k l P i u w M s SO p r c e lotovt 'OveraaHfiHefrgo iC lRAMpaek l
COMPUTER Nascom Wicrocomct/e's
A C O R N The Acorn Atom must rank as the best introduction to computing; on the systems side because it allows you painless access to assembler and machine code; on the applications side because of its superb graphics and powerful version of Basic. Based on a 6502 the hardware is easily understood and control ot external equipment is facilitated by a readily accessible bus.
N A S C O M The ultimate for hardware and software buffs alike. A totally flexible design based on the widely accepted Nasbus. Unlimited expansion possibilities supported by numerous independent manufacturers. Your number one choice if you want to develop a disc based CPM system suitable for business applications.
P R I N T E R S E ison from £345.
C H I P S 2114 4116
£1.25 £1.25
4118 £6.00 All prices exclusive of VAT
OFF 24a A b b e v i l l e R o a d L o n d o n S W 4 9 N H
2532 £8.00 2516 £4.50 6522 £6.00
[ Tel: 01 675 4557
01 674 1205
C O M P U T E R 100 LIMITED
MZ-80K S P E C I A L OFFER! I N C L U D I N G B A S I C T A P E A N D P R O G R A M M I N G M A N U A L
A proper full size microcomputer for less than the real
cost of a toy microcomputer . The Sharp comes with
4 8 K of R A M and the screen and cassette are built in,
instead of being expensive extras.
Full range of all Sharp peripherals stocked at highly competitive prices Ring for further details
C o m p u t e r 100 L i m i t e d 7 S o u t h c o t e P a r a d e S o u t h c o t e F a r m L a n e
S o u t h c o t e R e a d i n g , R G 3 3 D 7
R e a d i n g (0734) 584545
C O M P U T E R 1 0 0 L I M I T E D N a m e : _
I I | A d d r e s s :
I
M A I L O R D E R F O R M
Price is inclusive of V A T at current rate of 15%
I I I I Card No:
M a i l T o : C o m p u t e r 1 0 0 L i m i t e d
Post Code: T e l :
I Add £7.50 carriage/insurance to Mail Orders I; S o u t h c o t e P a r a d e , S o u t h c o t e
R e a d i n g , B e r k s , R G 3 3 D 7
YC 2 .'82
76 YOUR COMPUTER. FEBRUARY 1982