1 The PCW
Range
1.1
Models
1.1.1 -
8256 & 8512
The
first PCW to appear was the 8256 in 1984/5 at an initial rrp of £399 ex VAT. This comprised a green screen
monitor in a grey plastic case, 256k of RAM memory, one 3" floppy disc
drive and a 9 pin dot matrix printer. The disc drive, mounted vertically beside the
screen, had just one read/write head so the double-sided "CF2"
discs had to be turned over to use the second side. Each side accommodated 40
data tracks (numbered 0 to 39) giving a total formatted space of 180k, of which 173k was available
for user data storage (the balance being used for the system track and
directory). This disc format is variously known as Single Density (SD),
180k or 173k.
The
limitations of the 8256's RAM memory and disc capacity soon became evident so it was joined
within two years by its 'bigger' brother,
the 8512. Though equipped with 512k memory, the only discernable difference in
appearance was the second disc drive fitted beneath the
first. Unlike the upper (A) drive, the lower (B) drive was fitted with two read/ write
heads enabling both sides of the disc to be accessed simultaneously. It also
worked at double the A's data packing density - 80 tracks per side - to give 720k
total capacity and 706k available for data storage. This disc format is
variously known as Double Density (DD), 720k or 706k, the 160 tracks (numbered 0
to 159) being arranged with odd numbered tracks on one side and evens the other
in order to minimise disc drive head movement.
Both
the 8256 and 8512 were supplied with two single density master program discs, one
containing the LocoScript 1 WP program and CP/M operating system, the other
additional CP/M programs, help files and the DrLogo graphics package.
Unlike
PC printers, the PCW's printer took its power from the monitor and featured no
buttons to press, all controls being from the PCW's keyboard when in 'Printer
Control' state courtesy of the PTR key. Both the 8256 and 8512 were initially
supplied with 'A' series printers (an A on a sticker underneath and blue
paper-thickness lever inside) thence 'C' series (C on the sticker and red lever),
the C's featuring an arguably better print head but decidedly inferior bail arm
springs (which is why one sees so many C's ingeniously equipped with rubber
bands to keep the bail arm against the paper !).
An
elderly 8256 and a typically cluttered 8512
External
printers were not directly supported but by fitting a CPS8256 unit to the rear
expansion port, both a serial and a parallel port could be added. As the
supplied Loco 1 didn't support external printers, this was only relevant for
those who upgraded to Loco 2 or purchased other software which did eg Desk Top
Publishers.
The
PCW's success was not confined to the UK - they were sold abroad in considerable
numbers, some even being manufactured in Spain and Germany as well as the far
east, the German models assembled by Schneider in particular differing in the way the printer was
connected to the monitor.
Largely
thanks to the bundled LocoScript word processor and the Mallard basic
programming language, both of which were developed by Locomotive Systems of
Dorking, the PCW 8256 was way ahead of its time in so many respects. It took
Bill Gates a further ten years to borrow the Limbo principle and re-christen it
'the Recycle Bin' and over 20 years to come up with anything in Word which
approached the flexibility of LocoScript's multiple Copy and Paste facilities.
1.1.2
The 9512 and 9512+
Although
the 8000 series' dot matrix printers were flexible - allowing bold and italic in
variety of type sizes not to mention supporting Greek and Cyrillic - the print
quality was hardly suitable for professional use ... and Amstrad wanted to break
into the small office market. The answer was the 9512 in a more stylish cream
case and a daisy wheel printer. Fitted still with 512k RAM, the 9512 had a
single 720k floppy drive mounted horizontally beneath the monitor screen, the
latter featuring white type on black background rather than the green of the
8000 series.
The
print quality of the daisy wheel made it eminently suitable for many offices,
notably solicitors and accountants for whom the lack of italic and variable type
sizes was outweighed by the printer being able to take A4 paper sideways
(landscape) for large spreadsheets. Many writers also found the 9512 a better tool than an electric
typewriter but, particularly when inspiration came late at night, the noise
akin to canon-fire of the daisy wheel printer in action was not always popular with their partners vainly
trying to sleep.
Another
printer-related problem was the inability of the 9512's power supply unit to
handle the power surge caused by connecting or disconnecting the printer whilst
the PCW was switched on. This almost invariably killed the PCW's main
processor chip. A warning label was affixed to the printer but this was all too
easily removed or ignored so many a 9512 suffered a swiftly truncated life from
this cause.
Recognising
that the supplied daisy wheel may not be the answer to every maiden's prayer,
Amstrad fitted the 9512 with a conventional PC-type parallel port from the
outset and the ensemble was bundled with an early version of LocoScript 2 which did support a
limited range of external printers. The second 720k master program disc
contained all the CP/M and Dr Logo programs etc.
By the
early 1990's, 3.5" floppy drives had become the norm for PC's (until this
time they had mostly been 5.25") and 3.5" discs were not only becoming
widely available but also decreasing in price whereas both the now non-standard
3" drives and their CF2 discs were becoming more difficult to source as
manufacturers switched production. Amstrad's next move was therefore to fit the
9512 with a 3.5" drive and, for reasons known only to their marketing
department, called it the 9512+. As will be described in more detail later,
although physically the 3.5" 720k discs were the same as those used on
PC's, the disc format used was still CP/M so were not readily readable
on a PC.
The
9512+'s daisy wheel printer was identical to the 9512's but a sheet feeder
attachment option was made available to make it more suitable for office use and
Loco 2 was upgraded accordingly to support this feature. A more innovative 9512+
option was a Canon BJ10e Bubble Jet printer instead of the daisy wheel - a
radical departure for Amstrad as all hardware hitherto supplied with their PC's
and PCW's had been re-badged as Amstrad, and is all the more surprising as the
Canon BJ10 print engine was being used by other manufacturers in their own-badge
products.
The
original BJ10e only supported the Canon/IBM printer emulation so italic was
still unavailable and the difference between normal type and bold was not great
but at least it offered faster, quieter and better quality print than the daisy
wheel from a much smaller unit, albeit at a considerably increased price. The
BJ10e was soon superceded by the BJ10ex then BJ10sx, both of which also
supported the Epson printer emulation courtesy of a dip switch setting. At last,
italic type was possible on a 9512 plus a wider range of symbols and accents.
1.1.3
The 9256
Computer
pundits had been forecasting the imminent demise of the PCW from almost as soon
as they came out in the mid 80's but, from this time (early 1990's) onwards,
Amstrad now seemed hell bent on proving them right. Given that the 9512+,
particularly with BJ10e option, was far too expensive for many home users, the 9256
was seen as fitting the bill. It didn't. Why ? Despite it's re-styled looks, it
was really only an 8256 in disguise with white on black screen and 3.5"
disc drive. Despite the printer's sexy curved case, it was equally an old C series in
disguise. Worse, the 9256 was bundled with LocoScript 1 rather than 2 so no
external printer support and its 256k of RAM made it too restrictive for those
who wanted to upgrade to Loco 2 or later. Not surprisingly, most of the production went
to the remaindered merchants and were sold at knock-down prices just as had the
8256's after the 8512 and 9512 came along.
1.1.4
The PCW10
The
PCW press of the time eagerly anticipated the new model as having all sorts of
new features and so be the salvation of the PCW. It didn't and it wasn't.
Effectively just a 9256 with 512k RAM, its dot matrix printer could not compete
with the print quality being offered by stand-alone word processors from the
likes of Canon and Brother whilst, for pure computer use, it's incompatibility
with PC's (through using CP/M rather than DOS) and slow speed made it
unattractive. Equally, its limitations meant that it was not a viable or
realistic upgrade route either for existing 8000 or 9512 users so most
of those instead chose to
upgrade their existing kit by adding RAM and 3.5" drives from 3rd party
suppliers .... or switch to a PC. Few PCW10's were made and, again, most ended up with the remaindered merchants. Quite
why Amstrad decided to call it the 10 and persevere with the by then very dated
Loco 1.5 (instead of 2 as per the 9512) will become clear one day, but it was a
sad end to a ground-breaking range which had introduced hundreds of thousands of
people to the delights of computing and word processing.
1.1.5
The PcW16
This
model is mentioned here for completeness of the story but it was a PCW in name
only - or mis-name to be more accurate. Incompatibility with PC's was addressed
by using a DOS-based disc format while the bundled word processor was by Arnor
rather than Locomotive Systems so it was really more of an NC100 notepad with a
monitor than any development of the PCW range. Indeed, it could not be run as a
computer in the same was a 'proper' PCW so it was not an upgrade route for those
with ageing or failing PCW's whether they were used for word processing or as a
computer. As such - Amstrad's 3rd blunder in a row - few were sold via
registered dealers so most found their way on to the
remaindered market, a sad not to mention confusing end to the PCW range.
1.2
- Floppy Disc Drives and Floppy Discs
1.2.1
The drives
As
mentioned above, the 8256, 8512 and 9512 were supplied with 3" drives
which took CF2 discs whereas the 9512+, 9256 and 10 were fitted with 3.5"
drives and used standard PC type MF2DD 720k discs (reformatted, of course, to
suit the CP/M operating system). Note - some 3.5" drives will also accept MF2HD
1.44mb high density discs (and use them as per 720k's), others will not.
The
1st drive (the one the PCW is booted from) is drive A and any second drive is B.
Where a hard disc has been added, the 1st partition is generally C (as on a PC).
On single drive machines, addressing the drive as B is permissible as CP/M
supports a means of identifying two discs which need to be swapped back and
forth as being in
drive A or B.
Note
that whilst 3" 720k drives can read from (but not write to) 180k format
discs, single density drives cannot read 720k discs so programs will report them
as "not formatted or faulty".
All
the 3" and most of the 3.5" drives are belt driven - the Achilles Heel
of the PCW. The drive belts - glorified rubber bands - perish with the passage
of time and tend to set in one shape if not used for some time. "It worked
when I put it up in the loft 5 years ago" is an oft heard boast, but more
often than not it won't when subsequently retrieved and an attempt made to start
it. Merely fitting a new belt is not the panacea for all ills claimed by many
because rotational speed of the disc is crucial for correct reading &
writing and the belt may well have failed because of partial or total seizure of
the main bearing. The bearings were lubricated for five year life ... but in
many cases that was 20 years ago! Moreover, fitting a new belt can destroy the
head alignment. Alignment to the concentric disc tracks is equally important for
successful operation; misalignment generally arising from worn sled motor
bearings (the motor which moves the read head across the tracks) or physical
damage arising from trying to load a damaged disc or withdrawing a disc before
the motor has stopped turning.
1.2.2
- The Discs
3.5" discs only fit into their drives
one way up but 3" CF2's will fit either
way because the same physical discs are designed to suit all PCW models.
Care must therefore be taken as they may be used in two different ways:
-
Single density
180k format - PCW 8256 & 8512's 'A' drives - have just one read/write head so you have to turn the
disc over to access the other side. By convention, these are
called the 'A' and 'B' sides and each can hold 173k of data after
formatting. The 40 tracks per side are numbered 0 to 39.
-
Double density
720k format - 9512 and 8512 'B' drives - not only pack double the data into the same space but also read
BOTH sides at once so the capacity is four times as much - 720k (706k for data after formatting). Once a
3" disc has been formatted as double density,
the whole of the disc has been used so DO NOT turn it over in the hope of another 720k on the other side!
If you do, you'll wipe the lot so
make a habit of using the side marked 'A' (or '1') uppermost (9512)/to the left
(8512) and mark the spine label accordingly by barring out the B or 2. The 160
tracks are numbered 0 to 159.
Some early manuals recommended
using only of 'CF2DD' discs for the 720k Double Density format. Don't
worry - any 'decent' CF2 should be able to be successfully DD formatted but,
as with any disc formatting, it is wise to Verify the disc before use.
However,
beware relying on
sub-standard discs! When the leading disc manufacturers ceased
production of CF2's, a mass of horrid discs were imported from
southern Europe and sold under a variety of names, including (wrongly &
illegally) Amsoft. These are prone to sudden and complete failure and
can be recognised by having criss-cross hatchings on the disc case
and white write-protect levers in the leading edge of the disc (white
showing through the two smaller holes when the disc is laid flat).
Maxell discs are plain surfaced (no hatching) with red levers whilst
proper genuine Amsoft ones are hatched but write protection is by a white
slider tab on the rear left of the upper surface of the disc (so when
laid flat, there's a hole showing white on the right but a
rectangular slider tab on the left).
Whilst
talking of write protection, it is worth noting that most program master discs
were manufactured without write-permit tabs so their complete absence does not
indicate a damaged disc.
1.3
Disc Format
180k
discs have 40 tracks and 720k's have 160. Each track is divided into 8 sectors,
the sector being the unit of transfer to/from the disc.
-
The
first track of the disc - track 0 - is devoted to system information,
notably the format type and number of tracks. On boot (start-up) discs this
is followed by the boot program - the one which starts the snowball of
intelligence gathering in motion by loading an embryo operating system and
telling it to go looking for the next stage - the loading of an EMS program
(or EMT on 3.5" models), eg CP/M or LocoScript.
-
Track
1 contains the all-important directory, or in 720k format, the first part of
it. Each 32 character entry contains details of the name of the file, the
group it is in, it's size and the location on the disc of the constituent
parts of the file. As on PC's, the constituent parts may not be consecutive
data 'blocks' - on well-used discs they may be scattered all over the
(fragmented) disc. A single directory entry can only accommodate files up to
16k so, for files larger than this, 'continuation' entries are needed for
each 16k of data. Each sector of the directory contains 16 entries so, if a
disc read error occurs here, up to 16 files may be 'lost'.
-
The
rest of the disc is available for data storage and is addressed by means of
a unique 'block' number. On 173k discs these blocks are 1k in size but on
larger discs (720k and drive M) these are 2k in order to keep the block
number within the permitted numerical range. This explains why files copied
from 173k to 720k (or drive M) can apparently increase in size to the next
even number of k and, conversely, files copied to 173k may appear to reduce
in size.
1.3.1 -
Formatting Quirk - Upside down & mixed formats
It was
stated above that turning a 720k disc upside down and formatting the B side in
the hope of gaining a further 720k of space on the disc would result in loss of
the initial formatting, and therefore all the data. This is not quite totally
true.
A 'naked' disc in fact has space for around 168 tracks, not 160, and due
to the slight offset of the read/write heads, the first 8 tracks of the 'upside
down' (B side) format will use space not used by the A side formatting and, by the same
token, leave the last 8 tracks untouched. When turned back over to the A side,
these untouched tracks are its tracks 0 to 7, which includes the directory.
Hence, when inspected in (say) LocoScript, all the original files of the A side
format will be listed and the attempt to gain a further 720k will appear to have
been successful. Wrong! Any attempt to access any of the listed files will be
met with "Disc Address Mark Missing" unless the whole file happens to
reside within tracks 2-7.
So do
be careful when formatting -
-
Don't
be greedy by trying to get 1440k out of a 720k disc !
-
Smell
a rat if a disc verifies perfectly up to track 7 then collapses in a heap
with Disc Address Mark Missing on every single sector of Track 8 onwards.
-
The
same formatting quirk applies when re-formatting a former 180k disc as 720k
- the first 8 tracks of the B side won't be touched so loading it B side up
will give the appearance that it is a 180k disc at the same time as the A
side reports it as 720 !
-
Don't
mix formats if you have confidential or sensitive info you want to get rid
of because, if you do mix, some files from the previous format may still be
readable.
-
If
you have both 180k and 720k drives, always load discs of unknown type into
the latter and, if apparently conflicting formatting info appears, use
Disckit to determine which is the complete format.
-
If
the B drive of your 8512 has given up the ghost but you are still
soldiering on with just drive A, beware that 720k formatted discs loaded
into drive A will report that they are "not formatted or faulty"
so tempt you to overwrite potentially valuable data.
-
Don't
rely on what the disc label says is on the disc !
1.4
- Drive M
Drive
M (or simply M:) is the 'Memory Drive' - part of the PCW's RAM memory given over
to acting just like a physical disc drive. Anyone who has ever tried copying a
file from one disc to another on a single floppy drive PC will readily
appreciate this PCW concept - just copy A to M, switch discs then copy back M to
A.
Two
other important facets of this are speed and flexibility. Speed because drive M
works at electronic speeds rather than the mechanical speed of a revolving disc,
flexibility because copying frequently used files or programs to M at the start
of a session saves much disc swapping later on. Hence, when loading, Loco loads
printer driver files, templates and the LocoSpell dictionary into M so that they
are available whatever disc is loaded and, similarly, the standard CP/M start-up
loads several useful programs into M. The downside of this that Start-up is
prolonged and/or valuable working space is taken on M by files that are not
required during the session.
HEALTH
WARNING
The
contents of Drive M are lost when you switch off the computer or re-boot or
there's a power cut .... so always save valuable work on a physical disc
as soon as practicable ! (this is not an idle warning - I have both the postcard
and T-shirt to prove it!)
Continue
to Part 2 - LocoScript - Continue
to Part 3 - CP/M
On
to part 4 - How to Run Disckit
