An apparatus and method are disclosed that can adapt off-the shelf PDA devices (90) to user input/output applications such as data entry applications and cellular phone applications. The resulting apparatus (10) may be sized and shaped to be durable and facilitate handheld operation when the user is mobile during use. The apparatus provides features required for portable data entry such as key entry, barcode scanning, radio frequency identification, and wireless local area network (LAN) as well as wide area network (WAN) communications. The apparatus may be operated (a) in a slave mode with inclusion of a PDA device (90) for use in certain input/output operations that are processor intensive as well as (b) in a stand-alone mode without inclusion of a PDA device (90) for use in certain other input/output operations that are not processor intensive.