US-based firm Disk/Trend expects the worldwide market for removable storage devices to hit around $3.9 billion this year and grow to in excess of $5 billion by the year 2001. Breaking the market up into five segments, magnetic rigid disk cartridge drives, PC Card rigid disk drives, floppy disk drives, small optical disk drives, and cards using flash memory technology. Demand for the different technologies is, according to Disk/Trend, dependent upon demand for devices such as digital cameras - which will drive the demand for flash memory cards. Sales of high capacity floppy drives are increasing, but there is confusion as to which flavour users should adopt - Iomega, Syquest, 120Mb LS-120 and so on - Disk/Trends claims. Other manufacturers are readying themselves to break into this market, including Sony, Swan Instruments and Caleb Technology. Disk/Trends estimates the market will grow to accommodate sales of 33.4 million of this type of drive by 2001. This growth will suppress the market for standard 3.5 inch floppy drives, although the format will be around for the foreseeable future, the research company said. Shipments of flash cards are expected to rise from 4.5 million in 1997 to 19.6 million in 2001. Magnetic rigid disk cartridges are expanding into new markets such as video editing and multimedia mastering as the technology improves to give higher capacities at lower prices. One sector of the market expected to suffer over the next three years is the market for PC Card drives. Disk/Trends claims the market for PDAs and other sub-notebook devices has turned out to be significantly smaller than had been expected and this will impact on the PC Card drive manufacturers.