These pics were scanned from this japanese magazine by me.
Please feel free to take 'em and use 'em for whatever you like, but a link back would be appreciated.
None of this hardware was released, although as you can see the CD ROM and Monitor devices
at least made prototype stage. Both of these were actually released in very different form
as the CD ROM and Duo Monitor.

pc engine CD ROM prototype
pc engine CD ROM prototype pc engine keyboard prototype pc engine duo monitor prototype
pc engine computer link module adaptor pc engine modem prototype
pc engine duo monitor prototype