Peripherals
Several new Apple-produced peripherals were developed for the Apple III. The original Apple III came with a built-in real-time clock, which was recognized by Apple SOS. The clock was later removed from the "revised" model, and instead was made available as an add-on.
Along with the built-in floppy drive, the Apple III could also handle up to three additional external Disk III floppy disk drives. The Disk III was only officially compatible with the Apple III, although the Apple III was able to use the Apple II's modified Disk II disk drive and vice-versa.
With the introduction of the revised Apple III a year after launch Apple began offering the ProFile external hard disk system. Costing US$3499 for 5MB, it also required a peripheral slot for the ProFile controller card.
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