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IHARDWARE REVIEW
QL Delta Disk
Ray Elder goes to sunny Staines to
investigate Technology Research's new
interface.
'Hello?'
'Hello,' said a voice. 'It's
been a long time.'
'Yes,' I said, not having any
idea what had been a long time
and wondering which of my sins
had found me out.
'John Rutherford speaking,
TRL.' the voice said, I breathed
easy knowing we weren't going
to go through the 'Bet you don't
know who this is' routine.
'Why don't you come down
and see our new QL disk interface?'
John continued, and so, a
year after I last travelled to
Staines I found myself ambling
west to visit Technology
Research once again.
On arrival, nothing had
changed outwardly, but inside
the building the company had
changed rooms and I once
more wandered the maze that is
Unit 1 8, When I arrived, the first
thing that struck me was the
neatness and comfort compared
to their previous abode.
I was ushered into the main
office where it was pleasant to
renew the acquaintance of
John, Steve Tam and Steve
Mok. Also to meet C. Tang the
production manager and Y.
Cheuk the marketing director.
Many happy moments passed
discussing the state of computing
in general, the QL in particular,
and their interface in
brief. I left with not only the
Delta interface for the QL but
also a new version of the Spectrum
disk interface, the Beta
Plus. 'There are a few surprises
in that one for you,' said Steve
with a glint in his eye.
I took the Delta manual home
to read, because by the time I
got to the office it was well past
6,00pm (overtime accountant
please note) and anyway I prefer
to read instruction manuals
before trying things out, it can
save a lot of frustration and even
expense!
It took about twenty minutes
to read the whole thing, I liked
the simple informative manner
in which it had been written —
no previous knowledge is
assumed — and not only are
connecting and operating in-
structions given, but also an
outline of disk handling and disk
drive types. Although it helps if
you have a little computing
knowledge I felt that someone
who had bought a QL to use for
business and had no knowledge
of BASIC would be able to
operate this system without too
many problems.
After reading the manual,
even without access to a
machine to try things out, 1 felt I
could operate the system.
Theory
The Delta Interface in basic form
contains the Disk Operating
System (DOS), a parallel printer
port (Centronics) and a RAM
Disk system. Extra on board
memory of 64K or 1 28K can be
supplied as an optional feature.
The DOS was written by one
of the QDOS (the QL's operating
system) authors and is therefore
fully compatible with both
QDOS and the microdrive operations.
Any choice of disk drive,
5.25", 3.5", 3", single or double
sided, 40 or 80 track, and
any combination of up to four
drives can be used. The interface
automatically determines
which type is being used and
performs accordingly.
Provided that the disk size is
the same, many disk drive files
are compatible, ie. a file written
on a 40T SS drive can be read on
an 80T DS drive. And, an auto
boot facility is also provided.
Most of the operating com
mands, except for a few special
functions, are the same as the
existing microdrive commands.
All you have to do to use the disk
drive is to use 'flp' instead of
'mdv' in SAVE/LOAD commands.
If you are using the
printer port or the RAM disk then
use 'par' or 'ram' instead of
'mdv',
These commands are mixable,
so COPY-mdv 1-file TO
flp 1 -file will copy 'file' from
microdrive 1 to disk drive 1. The
names of these devices can be
swapped around so that built in
SAVE/LOAD functions may
operate without program
modification, ie. FLP-USE mdv
will output everything to disk
when a microdrive command is
issued. Clever!
Practice
The interface is a neat unit
designed in the same style as the
QL, once plugged in it looks like
part of the machine. On the left
hand side of the case is the connector
for the cable from the
disk drive and at the back is the
connector for the printer cable.
The whole lot was assembled in
less than ten minutes.
Although the printer inter
face is one of the lesser functions
of the l/F it is very important
as most printers on the
market use this format, RS232
systems are available but usual
ly cost extra to fit.
This worked a treat and a par
ticularly useful function was the
ability to specify the size of the
print buffer. This can be to any
size, memory permitting (and
here the extra 128K was
useful), and the result is that a
lot of text can be held ready
while the printer is operating,
but the QL is left Iree for other
purposes,
The documentation was a lit
tie sparse on information here,
and a bit of trial and error was
needed to get all the operations I
wanted, but finally everything
came together.
Bought separately, such an
interface is priced at around
£39.95.
RAM disk
Another extra, but again a very
powerful one, is the ability to
use a RAM disk. If a program is
going to make many accesses to
disk files during its operation
then an area of memory (again
the extra 1 28K was useful) can
be used instead of the disk. This
is created by giving it a number
from 1 to 8 and specifying its
size in sectors. All the disk information
is transferred, altered,
deleted or created in this area
until the program is finished, at
which point the whole lot can
then be transferred back to disk.
This has two main advantages,
first an incredible increase
in speed, access is vir
tually instanianeous, and
secondly less disk use means
less wear and less chance of cor
rupted files. A little more
sophisticated knowledge is required
to use this and it's an op
lion that is probably only really
usable by accomplished pro
grammers. Of course, it's a
valuable facility for commercial
software houses to use in their
programs.
Disk drive
The amazing versatility in the
tolerance of drive types is handy
if you already own a drive. The
only thing that is not too clearly
stated is that the drive MUST
have its own power supply.
Using this was as easy as the
manual led me to believe, the increase
in speed and reliability
was comforting. Although we
have not tested it for a long
period of time, I have been using
TR's Spectrum interface for a
year now and it has not failed
once, therefore 1 have every
reason to trust in the reliability of
their QL interface.
In fact it was a joy to use, and
if this had been used instead of
microdrives when the QL was
first launched, Sinclair Research
would have had a hard time
keeping up with the orders. Now
that it is here it should make a
great difference to the
machine's potential.
I hope software houses will
make use of the facilities provided
when designing their programs,
and all users should consider
this unit as being an important
purchase. At the back of
the manual is a wealth of
technical information which
hard/software experts will find
invaluable. I may even abandon
the Spectrum and Tasword II
now that I have a reliable
medium for storing text on the
QL.
The QL plus the Delta Disk
drive means business!
Delta Disk Interface
£129.50: with 64K RAM ex
tension, £199.00: with 128K
extension £249.50, All prices
are inclusive of VAT, but add
£4.00 for p&p.
Technology Research Ltd, Unit
18, Central Trading Estate,
Staines, Middlesex TW1 8 4XE. •
16 ZX COMPUTING DECEMBER,JANUARY 1985