Practice makes perfect - if you're any in doubt about the above procedure try tearing off a few strips
of blank first.
Cleaning
After you've been through a whole reel, you'll find that some of the black material has been scraped
off the paper. Whilst you have the reel carrier out, the printer should be cleaned. The black deposit
should be removed from the recess where the reel carrier goes especially around the slot just
underneath the serrations, and from the rubber drive roller. Use only tissues or a soft brush -
chemicals are definitely out. Some of them will attack the plastic and may reduce your printer to a
shapeless black blob...
Also, don't poke anything into any of the apertures, as the electronics or mechanics may be damaged,
and don't try to take the printer apart. Dismantling is easy, reassembly may be more difficult...
ZX printer technical appendix
This section is written for people who wish to use their printer with machine code programs to do
things like high resolution graph plotting, alternative character sets, etc, and it assumes a knowledge
of Z80 hardware and software. For printing out ZX81 characters from a BASIC program you don't
need to understand this section at all.
General principle of operation
The printer functions in rather the same was as a TV, i.e. by scanning from left to right. A
conductive stylus is pulled across the paper at high speed, and where a black dot is wanted a pulse of
current is passed though the stylus. This evaporates the aluminium coating on the paper, and allows
the black backing to show through. To avoid the need to return the stylus quickly to the left hand
edge of the paper, there are in fact two styli, mounted on a moving belt, which follow each other in
quick succession. The belt and the paper feed roller are both driven continuously whilst printing; so
that when the next stylus comes round the paper has been moved up ready for the next line.
In order that the styli always stop off the paper, the BASIC commands slow the motor down for the
last two scans before stopping - this makes sure that graphicsalways "join up" if done in several
goes, and this feature should be put in any machine code program that requires the printer to stop
whilst the computer thinks about the next line. At full speed, each pen is on the paper for about
Use the feed button to get a manageable length of paper and/or to
make sure that the rinting is clear of the serrations. Less thant 2 or
3 inches of paper may be difficult to tear off properly.
(If you're right handed). Hold the printer steady with your left
hand; with your right, pull the paper across the serrations at a
farily steep angle. Don't try to pull the paper squarely across the
edge all at once.
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