Help, Tips & FAQ's 

for the Amstrad PCW,

LocoScript & CP/M

 

 

An introduction to the PCW range, CP/M and LocoScript 
plus tips and answers to frequently asked questions .... 

from

the PCW Disc Conversion specialists 

Click here for 'Printer Friendly' version in Rich Text Format

 

Contents :

1 - The Amstrad PCW

 

2 - LocoScript  (opens a new page)

 

3 - CP/M  (opens a new page)

 


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


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