The 1800HD is an older portable laptop/notebook computer with a 286 processor, serial & parallel ports, and a 3.5" disk drive. The Radio Shack web site indicates that its memory can be upgraded to as much as three megabytes, and an external 5.25" disk drive can be connected. Without any upgrades, it meets the system requirements for Windows 3.11 or earlier. Several web sites continue to offer compatible batteries for it.