The series consists of PCW 8256 and PCW 8512 (introduced in 1985), PCW 9512 (introduced in 1987), PCW 9256 and PCW 9512+ (introduced in 1991), PcW10 and PcW16 (introduced in 1995).
The PCW switched from 3inch floppy drives to 3.5inch floppy drives in 1991.
8 million units sold worldwide (over 200,000 in UK) [https://www.retroisle.com/amstrad/pcw/general.php Source].