Digital's PDP 11 systems are based on a compatible set of processors that use a - common architecture and a common instruction set. 104 MB MFM 5,25" systems offer the - widest selection of operating systems, languages, data management, communi- cations, and applications software in the industry. In addition, they can easily be connected to our larger VAX systems, to personal computers, to other vendors' mainframes, and into an Ethernet local area network. The Systems and Software chapters of this catalog give you quick and easy-to- use information about the hardware and software that will meet your require- ments. (As not all hardware options are supported by all operating systems, Soft- ware Product Descriptions should be consulted to verify support). The Processor Selection Chart on the following page compares Digital 104 MB MFM 5,25" systems-. - This chapter is divided into three parts: Q-bus systems, UNIBUS systems, and the Professional. The major differences between these systems are in the bus structure and the type and variety of peripheral devices they support. The Q-bus supports small, inexpensive computer systems including the MicroPDP 11/83, the 104 MB MFM 5,25", the MicroPDP 11/53, and the - - - MicroPDP 11/23. The UNIBUS for 104 MB MFM 5,25" supports the PDP-11/84, the PDP 11/44, and - - the PDP 11/24. And the Professional 380 has its own private bus. -