Fujitsu reed keyboard switches
Fujitsu produced numerous series of keyboard reed switch. The known reed switch series are FES-1/2/3, FES-4, FES-5, FES-8 and FES-9. Although the series names appear to have been mostly assigned in ascending numeric order, the DIN-compliant FES-4 was most likely the final type to be introduced.
FES-1 and FES-2 is the oldest-known Fujitsu reed design, and the lowest numerically. FES-2 is the illuminated version. These switches appear to be linear only, and are extremely rare. FES-3 is related to FES-1 and FES-2, but no details about it have been discovered.
FES-5 is a magnetic separation click-tactile reed switch apparently introduced in 1972. It was specifically designed for terminals with a focus on providing good operator feedback.
FES-9 is a reduced-height version of FES-8, being around 25% shorter. The product features and characteristics otherwise remain the same as FES-8.
FES-4 is a low-profile reed switch, possibly introduced to meet German ergonomic standardisation.