in september 1998, ibm japan demonstrated a wearable pc. its components included a lightweight monocular head-mounted display with a monochrome resolution, headphones for sound and video, a controller / microphone for control and a control unit. it ran windows 98 and featured a 233 mhz pentium mmx, 64 mb of ram, a 340 mb ibm microdrive and usb interface. it could be controlled by voice commands or through a hand-held tracker ball. it was intended to be marketed for maintenance, repair and system installation staff by allowing the user to call up information from reference manuals and reference books on the eye level display, keeping their hands free.