I shall take this from the beginning because there are,I know, people around who have been given or otherwise obtained a PCW without any software. They contact me to ask how to make the darned thing work!.
When the PCW was bought new it would have been provided with two discs to load either Locoscript or CP/M. CP/M is the operating system which runs all programs except Locoscript; Locoscript has an integral operating system based closely on CP/M.
Machines with 3" drives
3" discs come formatted in two ways; CF2 format which is nominally 180K each side (These discs can be turned over in the drive to access each side separately), and CF2DD format which is formatted 720K nominal and can only be used one way in the drive. When the first 720K 3" drives appeared, special CF2DD discs were sold at about double the price of the ordinary discs, but the standard discs proved to be of such a high standard that they formatted to 720K and the disks sold as CF2DD disappeared. Was it an attempted con? Unfortunately some new discs being made today are of inferior quality and will only format to 180K. You can only tell by trying them as in a 10-pack, some will and some won't.
The two formats came about because the first machine, the PCW8256, has one single-sided drive only, following the style of earlier Amstrad machines such as the CPC6128 and the Spectrum+3. However these machines format discs differently although the CPC6128 and PCW formats are partially compatible. The B: drive of the PCW8512 is 720K which can be confusing at first. Whereas 180K discs can be read on either side, 720K discs must always be put in the same way so should be clearly marked one side. Failure to observe this will result in a complaint from your machine but won't do any harm.
Machines can only be booted from the A: drive, so boot discs for the PCW8256 and PCW8512 are 180K and for other machines 720K. Although the PCW9512 has a 720K A: drive, software on 3" disc, apart from boot discs, is usually supplied on single-sided 180K format discs. The 720K drive can read 180K format discs, and the PCW9512 is supplied with a utility program, 8000COPY.COM, which can copy 180K format discs to 720K format discs.
Two boot discs were provided for the PCW8256 and PCW8512. The first disc has Locoscript version 1 on one side and CP/M on the other. The other disc contains utilities for CP/M, two programming languages, Mallard Basic and DR LOGO, plus some help files.
Later machines with 720K 3" or 3.5" drives, were also supplied with two discs, Locoscript on one and CP/M with utilities on the other.
Machines with 3.5" drives
Later PcWs (note the small "c"),
the PcW9512+,PcW9256 and PcW10 all have single 3.5" drives, although second
drives can be fitted as drive B:. They use only 720K discs for all purposes,
but many of the earlier machines, PCW8256, PCW8512 and PCW9512 have been fitted
with 3.5" drives, sometimes in place of, sometimes in addition to, the original
3" drives.
A favourite upgrade was to use a 3.5" drive as a B: drive for a PCW8256 or PCW8512
but these machines could also use a 3.5" drive as the A: drive. The disc can
be formatted to 180K each side without turning it over by using a switch.
These machines can be booted from a 720K 3.5" disc using special boot discs,
but a special file has to be included with a .FIB extent, presumably fooling
the machine into booting by telling a FIB.
Another popular arrangement was to use a 3.5" 720K drive as the A: drive and
transfer the single-sided 180K 3" drive as the B: drive. In this case .FIB files
would be needed for both drives, both different of course. They would have names
such as A35.FIB or B35.FIB.
Locoscript boot discs
The PCW8256/8512 was supplied with Locoscript version 1 but later machines were supplied with Locoscript 2 except for the PcW9256 which reverted back to Locoscript 1.
Locoscript 2 is an improvement on Locoscript 1 in several ways; it is faster, supports external printers and includes the facility to copy, format and verify discs. Locoscript 3 introduces scaleable fonts to enable different sizes of characters and Locoscript 4 enables graphic images to be imported and limited colour printing.
Within the various versions there are many sub-versions, and there is often a problem with compatibility between machines. Some versions run on one machine, a different version may be needed for another machine. It's not good enough to say "I want Locoscript 2 on a 3.5" disc"; the model must be quoted also. A typical name for a Locoscript boot file is J228LOCO.EMS where the 228 stands for version 2.28 which is one version among many for the PCW8256/8512. The file extent .EMT is also used on occasion.
CP/M boot discs
Similar problems occur with compatibility between versions of CP/M for the different models. A typical name for a CP/M boot file is J14CPM3.EMS which is CP/M 3 version 1.4, used with the PCW8256/8512. CP/M 3 is more often known as CP/M PLUS. The file extent .EMT is also used for some other versions. To make a boot disc, the file J14CPM3.EMS can be copied to any other disc and this is the only file needed to boot CP/M, but in other cases this won't work and the boot file has to occupy a special place on the disc, as in MSDos. The most sure way to do this is to make a copy of the entire boot disc then delete all files except the J??CPM3.EM? file.
Ron King
Andover, England
Email.......ron@king27.freeserve.co.uk