Gap appears in market which needs to be filled

I TOOK the slightly unusual step of buying your magazine before buying a computer. Despite my lack of knowledge, I found the articles interesting and informative.

Due to your recent special offer, I was able to purchase a ZX-81 kit, which I put together easily. Sadly, it doesn't work. It was then that I realised that kit builders have very few information sources on which to draw. Is this a gap Sinclair User could fill?

I wrote to Sinclair describing the problems and the company replied within a few days to the effect that most faults are caused by poor soldering. It made me wonder how many people, as myself, may not know what a correctly soldered component looks like and, presented with a machine which does not work, either give up or poke around causing real problems.

Perhaps an illustrated article showing the correct methods for handling components and building the ZX would help the would-be kit builder; no doubt mistakes occur in the same areas repeatedly and they would be highlighted.

Before learning to debug programs some of us would like to learn to debug the computer. Perhaps it is possible to return the unit to Sinclair, of course, but how much better it would be to finish the job oneself.

G Williams

We have published a new magazine, Sinclair Projects, to deal with problems like this.

Copyright worries

I AM very concerned about the topic of program copyrights. One of the reasons for buying a home computer as powerful as the Spectrum is to play faithful copies of arcade games hour after hour economically, and in the comfort of one's own home.

I would like to feel confident that if a new arcade game is invented one of the better software houses would produce a copy for the Spectrum without being hounded into changing it beyond recognition by a company which would not think of producing a copy itself.

Paul Edson

Cassette for 1983 tax

WE WERE delighted that the November issue of Sinclair User contained favourable reviews of our ZX-81 software products Comp-U-Share and Comp-U-Tax (Income Tax). I would like to make one point clear to your readers. Your reviewer refers to Comp-U-Tax being valid for the year to April 5, 1982, which was correct for the product provided to him for review.

We have, however, now released the annual update for the year to April, 1983 - the current tax year - which incorporates some improvements but should at the same time be familiar to existing users of the earlier product.

This confusion arose because we do not release for review, or any other purpose, products until they are fully operational and we are confident that we can supply them from stock.

R E Cooke-Hurle, Managing director, Micromega

Growth in 'Vapourware'

I WAS pleased to see your editorial in the November issue on the subject of what can be termed 'vapourware'. There is plenty of it about and anything magazines can do to help readers know what is really available when advertised would be a boon to them, although a curse to the advertisers.

Apart from the chain promises on my Spectrum, the last one being given to me as 'another two weeks' by telephone as the postman rang the doorbell to deliver the parcel, I have suffered from Microl Spectrum USE & LEARN, non-delivery and cancelled after one month; R&R Software, Golf delivered by return post; Adda Computers, printer interface ordered five weeks ago and I cannot get a word from the company; Hewson Consultants, 20 programs for Spectrum - I cancelled after 14 days; Bug-Byte, Spectral Invaders, delivered by return; Harris & Lochyer Associates, Spectrum keyboard did not get into production.

Apart from the two software firms, it frustrates one and makes one doubt the promises given to one by suppliers who are probably truthful. I feel that my best way of getting add-ons will be through a local shop, Microware in Leicester - where if it is in stock I can have it, but it restricts my choice not being able to rely on advertisers in the computer press.

May I be permitted to make two comments about Sinclair User. Some of the printouts are of such poor quality that they are no advertisement for the Sinclair printer, let alone being tantamount to unreadable. Of course, as you say, they should be computer printouts but you ought not to pay good money for inadequate printing. The alternative would be for submissions to be on cassette and you do the printouts which we could then read.

Second, I was delighted to see that an EPROM blower had won a competition. To give it two pages without any construction data for hardware buffs was a waste of paper. We would be well served if it had been a constructor article.

Keep up the good work.

Alan Batch

To answer your problem about the EPROM blower we have started a new magazine called Sinclair Projects intended for people who enjoy building hardware items for their machines. In the first issue, which appeared in November, we included an article giving details of the blower.

Basic video version

ON READING the August edition of Sinclair User, I noticed an advertisement and subsequent article promoting various pieces of hardware designed to give the ZX-81 an inverse video option.

Although inexpensive, the devices require that the owner drills holes in or re-wires his/her machine in a manner many users would consider to constitute mis-treatment of what may well be their best friend. The function can, of course, be performed by a Basic routine, though you would need an alternative equally absorbing pastime to occupy your mind during its execution.

There is nothing simpler in machine code programming than to provide yourself with just such a facility. I offer a routine which could sit neatly in a one-line REM statement at the beginning of the program, i.e., 5 REM 1234567890123456789.

The sequence would then be POKEd into addresses 16514-16532. This may then be called whenever required from within the Basic program with an instruction such as:

LET A=USER 16514

Much better than defacing a friend.

Phil Lester

Courage needed for machine code

YOU SEEM to be serious about trying to make sense out of that shambles of a series on machine code. Where do you get such courage? After a full page of the wonders you were going to offer us you said:

"When the program (figure one) is in, then type POKE 16514,128." It took dozens of attempts and restarts to discover that it should have read. "... is in, do not run it, but instead type ..." which was the only way I could get it to work as described.

Then came the gem: "Then we can enter our first machine code program but previously we call a machine code program."

Apart from the logic of "Then - but previously," I was still under the impression that I would find what a machine code program looked like, and "enter" and "call" it later but I understood 10 LET A=USR (16514) and entered that.

Was there now a machine code routine at address 16514 or was I supposed to put one there? and did line 10 tell the "program flow" to execute it there and then or later? Had I given a value to W, whatever W happens to be; were the 'B' and 'C' register alike now and, if so, how could I use it 'to advantage'?

The next two items of comprehensible information proved to be a table of instructions and a paragraph of instructions. On closer study they proved to be one item of information written two ways. I have given up long ago on explanations but I can understand the 'instruction,' '1 NEWLINE' and when I type it half the program vanishes, never to be seen again.

I am a ZX-81 owner with a few weeks' experience. Half a million ZX-81 s have been sold within the last year or so. That works out - on a ZX-81 if you own one - that nearly all those half million Sinclair users have also only a few weeks' experience, or months at the most,because the ZX-81 is essentially a first-time buyers' computer, the only really suitable computer for a first-time buyer, in fact.

What we are doing is learning the particular delights of presenting precisely-defined instructions in a strictly logical manner - to our computers and to one another. What a pity Sinclair User cannot share that pleasure.

Norman Gale

Printout welcomed

WITH ALL the people who complain about the printing in the program printout, I feel I must say a few words of praise for you. I have bought Sinclair User since April with the exception of June, and in all my copies I can find only five programs spoiled by the methods of printing. I think it makes the layout look better and I like it.

Also I have a hint for RAM wobble. I cured mine by using the point of a pair of scissors to press in the connectors to make the connection stronger with the ZX-81 edge connector. This makes it more difficult to take off and put the RAM pack on, but stops wobble. Also type this in with 16K:

10 LET LINE 20=USR 12345
20 RUN USR 5

A reader

Penfriend corner

I WOULD like a pen-friend who has a ZX-81 with whom I can exchange programs and other things.

Han Loke Su

I WOULD like a pen-friend of about 14 who owns a Spectrum so that we could swap ideas and programs.

Steve Kaul

Praise for Sinclair

HAVING READ page iii of Spectrum User, November, 1982, I felt compelled to redress the balance. I had to wait 15 weeks for delivery but was rewarded for my patience with an excellent microcomputer, a free cassette and a £10 voucher. After a few days' use the power supply unit failed. I was crestfallen.

I telephoned 0276 685311 (See John Catherall's letter) and three-and-a-half days later received a replacement power supply unit. If one works out the logistics I think it would be impossible to reduce that time. Good going, Sinclair.

As an innovator myself - recipient of more than one official award for my work - I can understand how unforeseeable difficulties can upset delivery promises and a good deal of innovation certainly went into the Spectrum. Undue modesty can also upset delivery by demand far exceeding expectation - see Inside Sinclair, pages 26, 27.

I am already looking forward to replacing Spectrum with Son of Spectrum, probably by early 1984.

Ronald Edge

Dry paper advice

USERS of the Sinclair printer who have been having difficulty getting a solid black print might like to try baking the paper very gently in an oven.

Aluminised paper is hygroscopic and will absorb any available moisture, making it difficult for the stylus to burn through the aluminised surface in the time allowed.

Always store your spare rolls of paper in their original sealed packages to keep them dry.

B Wigglesworth

Spectrum noise annoys

DO YOU or any of your readers know whether it is possible to get rid of the noise the Spectrum makes? If so, how?

P Bankes

So far as we are aware it is impossible to stop the low buzzing once the Spectrum is switched on.

Clean printer runs better

THE FOLLOWING tips may be of use to owners of Sinclair printers. After some time in use, and particularly after putting on a new roll of paper, the feed mechanism operates weakly, causing printing to be compressed vertically. Wiping the rubber drive roller with an acetone-moistened cloth removes a deposit of carbon from it and the paper then feeds properly.

On two occasions, with different printers, the mechanism has jammed.

The symptoms are rather like a jammed car starter; there is no response to LPRINT or COPY commands and if the feed button is pressed there is a subdued click but no movement.

If the bottom of the printer is removed, you will see a large nylon gear. Rocking it gently frees the mechanism - on one occasion a large lump of carbon fell out and I suspect that is the usual cause of jamming. Remember, however, that attempting your own repairs will probably invalidate the guarantee. I would certainly not recommend attempting to disassemble the printer any further.

I find also that the same printer operates differently on different ZX-81s; on some it seems very tired. On the Spectrum, it fairly thrashes away and I suppose that is due to a difference in the current available from the computers.

Colin Dickinson