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ZX81SCENE<br />
ZX81 Chatterbox<br />
Julian Chappel and his ZX81 ride again!<br />
Greetings to all ZX8 1 owners<br />
once again!<br />
I am very pleased to be able<br />
to report that, following the first<br />
appearance of ZX CHATTER-<br />
BOX in the last issue of ZXC<br />
your letters have been flooding<br />
in. Both of them! At this rate we<br />
shall be completely bogged<br />
down with the sheer weight of<br />
correspondence by the year two<br />
thousand one hundred and ten.<br />
Er . . . 1 have a very embarrassing<br />
admission to make, so I<br />
am writing this extremely quiet<br />
ly in the hope that this column<br />
has put in an appearance on<br />
these hallowed pages. I already<br />
have to apologise for a glaring<br />
'boo boo' in theJirst article.<br />
m very, very sorry.<br />
Right, having got the<br />
apologies out of the way we can<br />
get on with all the good bits.<br />
Don't listen to the owners of<br />
Spectrums and other lesser<br />
machines when they say that all<br />
the good points about the ZX8 1<br />
can be written on the back of a<br />
postage stamp in large capital<br />
letters. They knoweth not what<br />
they are talkething about. After<br />
all, we knoweth different, don't<br />
we? Even with the advent of<br />
machines capable of printing<br />
256 colours in an area the size of<br />
a flea's brain and sound good<br />
enough to put the London<br />
Philharmonic Orchestra to<br />
shame, the ZX81 still<br />
represents an excellent introduction<br />
to computing. It is no<br />
secret that the use of home<br />
computers is no longer the<br />
domain of the whizzkid. Many a<br />
whizzdad and whizzmum take<br />
an interest these days, but tend<br />
to be a little more cautious when<br />
entering the world of BASIC,<br />
binary and bugs than their offspring.<br />
Probably because it is<br />
their own money they are spen<br />
ding! It stands to reason<br />
therefore, that a ZX81 will have<br />
'em programming like a good'un<br />
76<br />
in less time that it takes to paint<br />
the Severn Bridge with a toothbrush<br />
and give a good indication<br />
whether or not further delving<br />
into the realms of computers<br />
seems attractive, all without<br />
parting with hundreds of pounds<br />
of hard-to-come-by cash. This<br />
brings us (ratherneatly I think! to<br />
the first letter this comes from a<br />
newcomer to the ZX81 who<br />
was presented with it as a 70th<br />
birthday present 1 Beats woolly<br />
socks doesn't it?<br />
(There will be a short delay<br />
before this letterdue toa second<br />
apology. I am very sorry that I<br />
didn't tell you what the first<br />
apology was all about J<br />
Now back to the letter. . .<br />
'Dear ZX Chatterbox<br />
As per the Oct .November issue<br />
of ZX Computing magazine, I<br />
would like details of the S.F.S.C.<br />
having been a recipient of a<br />
ZX81 on my 70th birthday! Not<br />
used as much as expected as yet<br />
but winter is coming.<br />
I have trouble (not unusual I<br />
understand?) with the LOADing<br />
program of various lengths both<br />
from commercial tapes and my<br />
own programs. What occurs is<br />
that apparently correct loading<br />
takes place as seen by the<br />
power meter, running to end but<br />
with no Report Code; as far as I<br />
know I have tried all ways of correction<br />
but to no avail.<br />
Yours<br />
W J Huggins, Slough'<br />
At a time when the ZX81 is<br />
regarded as something akin to<br />
the Dodo it may seem strange<br />
that there are still a substantial<br />
number of people acquiring new<br />
ones. (Don't be silly I mean new<br />
ZX81s not new Dodos!). This<br />
means that there are many<br />
ZX81 users who missed the<br />
press coverage this little black<br />
wedge received during its heyday,<br />
and as a result are blissfully<br />
unaware of certain facts that us<br />
old hands simply take for<br />
granted.<br />
Loading<br />
One such fact is that theZX81 is<br />
highly temperamental when it<br />
comes to SAVEing and<br />
LOADing programs. Another is<br />
that swearing at a ZX81 in a par<br />
ticularly obstinate mood has no<br />
effect whatsoever. (Except may<br />
be making it worse!) Hitting it<br />
with a hammer gives the advantage<br />
of relieving the user's pent<br />
up frustration with the offending<br />
machine, but also has the side<br />
effect of smashing it into little<br />
pieces. Not to be recommended.<br />
Here are some less drastic hints<br />
and tips towards reliable<br />
LOADing:<br />
Setting up the machine<br />
1 . The ZX81 was designed for<br />
use with an everyday portable,<br />
mono tape recorder. A<br />
dedicated data recorder will be<br />
little or no better unless the<br />
facility to adjust the azimuth set<br />
ting is incorporated. A stereo<br />
recorder (even a portable one)<br />
should be avoided, these may<br />
work but reliability will seriously<br />
suffer.<br />
2 . Clean the heads, rubber pinch<br />
wheels and drive spindle of your<br />
tape recorder thoroughly and<br />
regularly with cleaning fluid.<br />
Thoroughly dry and polish all<br />
areas with which the fluid<br />
comes into contact before reinserting<br />
the tape.<br />
3. Some recorders produce a<br />
feedback loop around the<br />
ear/mic sockets. Always<br />
remove the 'mic' lead when<br />
LOADing or the 'ear' lead when<br />
SAVEing. Make sure that the<br />
'ear' and 'mic' leads do not<br />
cross lor are crossed by) either<br />
the mains cable to the tape<br />
recorder or power supply<br />
transformer, or the lead from the<br />
power supply. Separate all leads<br />
as much as possible.<br />
4. Set the TREBLE control on<br />
your recorder to maximum and<br />
BASS to minimum (or TONE to<br />
high).<br />
5. For reasons best known to<br />
Uncle Clive, the ZX81 is less<br />
temperamental when the pro-<br />
gram name is used. Avoid using<br />
LOAD" " whenever possible.<br />
The signal<br />
When LOADing, the ZX81<br />
repeats all data read into<br />
memory out to the screen, giv<br />
ing those characteristic horizontal<br />
lines. This LOADing pattern<br />
can therefore give a useful indication<br />
of how the LOAD is progressing<br />
(but no more than that.<br />
It is by no stretch of the imagina -<br />
tion an accurate or infallible<br />
pointer).<br />
The black horizontal lines<br />
should be bold and clearly defined.<br />
They will be about 1 -2 inches<br />
wide Ion a portable TV) and<br />
the gap between each should be<br />
roughly equal to the width of the<br />
lines themselves. The width of<br />
the spacing will decrease with<br />
any increase of volume level. It is<br />
the definition of the lines<br />
themselves that gives an indication<br />
of uncertain LOADing. If<br />
they appear thin and straggly, or<br />
have a snowy effect (i.e. are<br />
flecked with a large number of<br />
little white dashes) and refuse to<br />
become clearly defined no mat<br />
ter what volume level, this is an<br />
indication of azimuth mis<br />
alignment.<br />
The 'business' part ol the<br />
playback head is a microscopic<br />
slot, the angle of which in relation<br />
to the passing tape is<br />
critical. The ZX81 is probably<br />
the most sensitive to mis<br />
alignment of any make of home<br />
computer. A good data recorder<br />
will have the facility to adjust<br />
this angle, usually in the form of<br />
a small hole positioned over the<br />
head into which an electrician's<br />
screwdriver can be inserted.<br />
Simply adjust the setting while a<br />
LOAD is taking place until the<br />
horizontal lines become bold and<br />
clearly defined.<br />
volume setting<br />
Once again the ZX81 can be<br />
very sensitive to the volume<br />
level used when LOADing. Too<br />
low and the LOAD will fail. Too<br />
high and the computer can<br />
mistake the normal operating<br />
noise of the recorder as part of<br />
ZX COMPUTING DECEMBER/JANUARY 1985
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