How to Use DiscKit, by Malcolm Surl

This article is an extract from Malcolm Surl's website - thank you Malcolm for your many years of contributing to the Amstrad PCW community!

How to use Disckit

The Disc Verify, Format & Copy Program for Amstrad PCW Word Processors     



    PCW 8256                                                    PCW9512        



This program, supplied as standard with all PCW's on the CP/M utilities disc, is a very useful tool  not only for formatting and copying discs but also verifying that discs are fully readable - very important these days with so many poor quality discs in circulation, not to mention the fallibilities of the disc drives themselves. 

It is broadly comparable to the similar facilities built into LocoScript 2, 3 and 4 but it gives more useful details about disc problems (notably the names of the files suffering from errors) and is normally far quicker & easier to use for disc copying.

Users of the 8256/8512/9256/10 still using the originally supplied version of LocoScript 1 will have come across Disckit before because it is the only way of formatting discs. However, 9512 users who have been brought up from the outset on Loco 2 (which supports disc formatting, copying and verifying on the f2 Disc menu), are often unaware of it.

The crowning advantage of Disckit for 9512 users and others with high density drives is that copying a disc is a much less tedious task on a standard 512k m/c because a full 720k disc can be copied in just two parts rather than ten or more under LocoScript. This is because less of the computer's RAM memory is occupied by the program itself so more of the RAM is available for holding the disc information being copied ... so it can do it in fewer parts (disc swaps).

For those with two disc drives (an A and a B), Disckit has the facility to read from a disc in one drive and write to a disc in the other. This means that copying can be done in one go without disc swapping. Moreover, for those with both 3" and 3.5" drives, this means that you can take a back up copy of valuable data from one drive to the other (eg from the more fallible 3" discs to the more secure 3.5" species) but, as with LocoScript, not all add-on drive combinations are catered for.

Disckit is designed to prevent incomplete / unsuccessful target discs from being used, whether from a fresh format or a copy. It does this (a) by offering only Cancel or Re-try as options when an error is found during formatting or copying (whereas when verifying, Ignore is also an option) and (b) by removing the format info in track 0 at the outset and only reinstating it upon successful conclusion. Hence, hitting C to Cancel during the format / copy results in an unusable disc ("disc not formatted, format not recognised" etc). Best plan is therefore to Verify all discs involved before embarking on a copy or re-format session.   


CAUTION . . . . . & Disc Types

  • Whenever copying or verifying discs using Disckit, ALWAYS write protect the disc you are copying FROM or that you are verifying .... just in case you make a mistake when swapping discs or hit Format instead of Verify! 

    The design of 3" disc write protect tabs varies by brand so may be a slider at the rear of the top surface or a lever within the leading edge of the disc. Whichever, if the write protect hole is open (so that you can see right through the round hole), it's protected; if you can see a red or white disc it is NOT. 

    On 3.5" 720k double density discs, write protecting is always by means of a slider tab (over a rectangular hole) on the under side of the disc - again an open hole = protected, blocked = NOT. High Density 1.44mb 3.5" discs, which can be used on a 9256/9512+/PCW10 without adaptation, have a second rectangular hole in them (to denote they are HD discs) without a tab and must not be confused with the write protect hole. 

    NB. Many manufacturer's original program discs are intentionally made without write protect tab sliders or levers - to stop accidental over-writing - so this does not signify that the disc is damaged.


  • 3.5" discs only fit into the drive one way up but 3" CF2's will fit either way because the same physical discs are designed to suit all PCW's. Care must 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.

    • Double density 720k format - the drives fitted to the 8512 as drive 'B' & all 9512 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' uppermost (9512)/to the left (8512) and mark the spine label accordingly.

  • 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 DD formatted.

  • 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) 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 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).


To Start Disckit

  • Switch on your PCW and insert your CP/M utilities disc (or preferably a copy of it) into drive 'A'

  • As soon as the initial "lines going down the screen" display switches to the CP/M start-up screen, hit the STOP key a couple of times. This aborts any automatic copying of files from drive A to M which is not only unnecessary for Disckit but also reduces the amount of RAM available for storing disc images when copying.

  • At the ensuing A> prompt, type in DISCKIT then hit the Enter key. Note the spelling but it may be entered in either upper or lower case (as with all CP/M commands).

  • When prompted to do so, remove the CP/M disc from Drive A

  • The main menu screen appears with a representation of the f1/3/5 function and Exit keys


  • Once in Disckit, all commands are by single keystroke ie no "Enter" is required to confirm an action.

  • The following descriptions relate to the most common program version (1.2 - as shown on the initial screen display). Earlier versions are similar in operation but the screen prompts are less "user friendly". 


To Verify a Disc

  • Hit the f1 key.

  • On two drive m/cs, an extra menu appears asking for the drive letter so hit f1 or f3 as appropriate. This display is geared to look like an 8512 so the upper of the function keys, f3, is used to signify the upper drive (A:) and the lower, f1, the lower drive (B:) so is a bit confusing on a twin drive 9512 where they are side by side! On an 8512, if you are not sure whether the disc is single or double density, choose drive B as this can read both single and double whereas the A can only read singles so will report a double as 'not formatted'.

  • A screen appears asking you to confirm that this is what you want to do. Insert the disc and respond with Y as prompted.

  • The display will show progress by an incrementing track number - there are 40 tracks on a single density disc ('CF2 format' - 0 to 39) and 160 on a double density disc ('CF2DD' - 0 to 159).

  • If problems do arise, the track number, sector number and name of the file involved will appear followed by the entreat to Retry, Ignore or Cancel. Initially try hitting R to re-try in case the problem can be overcome by a further 10 attempts to re-read, during which the disc drive will emit the characteristic "eee-awe" ("donkeying") sound as the head retracts and re-positions in an attempt to re-read the affected sector. If failure still results on the same sector, note the track, sector and file name then hit I to ignore and continue then, upon completion, try the disc in a different drive (if possible) to determine whether the problem is with the disc or the drive alignment/slipping belt. On really hopeless cases, hit C to cancel the verification and return to the main menu.

Note: If a CF2 format disc verifies fine until track 8 then fails on every sector, this is a sign that it has been reformatted as double (CF2DD) with the other side uppermost .... so try it that way up in a DD drive. For technical reasons, the later DD formatting does not quite obliterate the original CF2 format. The original directory is left intact thereby giving the misleading impression (eg in LocoScript) that the disc is a valid CF2 and the data is retrievable. This is not so unless a complete file resides totally within the first half dozen data tracks.

  • When complete, remove the disc from the drive as prompted then either hit "Y" to verify another or any other key to return to the main menu.


To Format a Disc

  • Hit the f3 key

  • The prompts and action from hereon are the same as for verifying above except that, when a disc problem arises, the only options proffered are Retry and Cancel. Note that if you do Cancel a format, the disc will not be useable because the system and directory tracks (0 and 1) are only written at the end of the process if the rest has been successful.

  • When you first insert a freshly formatted disc into LocoScript, the Disc Manager screen will report the drive as having 173 or 706k free, but there will be NO columns for it in the lower (files) part of the screen. Don't panic! With no files on the disc there's nothing to display .... so LocoScript omits the file columns and the cursor left/right keys have no effect. The trick is to use the SHIFT+Cursor keys to move the upper Group cursor (highlight). A good way of initialising a new disc is to select TEMPLATE.STD on drive M, select Copy file (f3 in Loco1 or f3 menu in Loco2/3/4) then hit SHIFT+Cursor Left until the highlight reaches Group 0 of the new disc then hit Enter twice. Once the file has been copied, the disc manager screen will refresh and a column for this group will magically appear! 


To Copy a Disc

  • A wise precaution here, especially on 3" discs, is to verify the 'source' disc ('disc to Read') and to format the 'destination' or 'target' disc ('disc to Write') before undertaking the copy so as to prove that both discs are fully OK (or that any problems on the source are confined to an unused area ("fortunately this does not matter" report).

  • Having write protected the source disc, place it on the left hand side of the top of your PCW and the destination disc on the right (so that you are working naturally left to right and feed the discs in the correct sequence).

  • Hit the f5 key

  • On single drive machines, where you can only read from a disc in A and write to a disc in A, simply insert the source disc and respond Y to the "Are you sure?" prompt.

  • On twin drive machines, select the drive of the source disc (with f1/f3 as described under Verify) then choose the destination (again with f1/f3). Note that on an 8512 you can copy a 180k format disc by placing the source in B and the target in A, but not vice versa as 720k discs cannot be read in a single density drive. Insert the discs, re-check that they're the right way around then hit "Y".

  • When reading from and writing to the same drive, respond to the "Load disc" prompts as necessary (switch discs then hit a key). 180k discs will copy in one hit, 720's will take two (tracks 0 to 79 first time then 80 to 159) except on a 9256 when it will need four swaps.

  • When complete, a wise move is now to Verify the destination disc.


To Quit the program

  • From the main menu, hit the Exit key to return to the CP/M A> prompt.

  • If you have now finished with the PCW for this session, just switch off. If you now want to start up LocoScript, hit Shift+Extra+Exit altogether to re-start the PCW then insert your Loco Start of Day Disc (SOD disc).