l Large to medium rugged frame or cabinet — Some  frames  or  cabinets  use  a  stationary  or  sliding chassis or assemblies or stationary racks or card cages that contain individual modules or printed circuit boards. The functional and support areas include a central   processor   unit   (CPU),   memory   units, input/output controller boards for various peripherals, I/O connectors, power supply unit(s), and blower motors  for  cooling. (NOTE: Some minicomputer frames  or  cabinets  also  contain  the  peripherals-disk drive units, magnetic tape units, and paper tape units.) . Control  and  Maintenance  Panel  (CMP)  or computer  control  panel  —Controls  operation  of  the computer   and   is   used   to   perform   maintenance (preventive and corrective). l Specific power requirements (frequency and voltage). l Specific  cooling  requirements (air and/or liquid cooling). Microcomputers Microcomputers,  personal  computers  (PCs),  are small, lightweight, and portable. Some of them are more   powerful   than   some   of   the   older,   larger mainframes  and  minicomputers.  Microcomputers  are unique in that the heart of the computer (the CPU) is contained on a single integrated chip (IC) and the entire computer system is contained on a handful of printed circuit boards located inside a small compact frame or cabinet. In some cases a complete microcomputer is located on a single chip; the CPU, co-processor, and memory. Some micros/PCs are high-speed, multi-user, multi-tasking  units.  Traditionally  micros  are  used  for word processing, database management, spreadsheets, graphics, desktop publishing, and other general office applications. Currently, micros and PCs are being used  for  tactical  support  systems,  such  as  Naval Intelligence Processing Systems (NIPS) and Joint Operational Tactical System (JOTS). Micros and PCs can also be used as a SNAP system for shorebased operational   commands,   such   as   ASWOC.   The operational  programs  for  PCs  used  for  a  tactical support system are supported externally by technical teams. These operational programs are also updated as systems are added or replaced. Programs that are used for word processing, graphics, and so on are abundant and can be obtained through civilian vendors and software support teams such as Commander Naval Computer  and  Telecommunications  Command (COMNAVCOMTELCOM).  Training  for  micro- computers  is  obtained  through  formal  A  schools, civilian contractor schools, and OJT. Training for micros  is  not  NEC  producing.  Figure  1-5  is  an illustration of a typical microcomputer. The physical features of microcomputers are very different from mainframes and minis. The following is a brief description of a typical PC/desktop system. l Small  compact  frame  or  cabinet —PCs are uni- que in that the frame or cabinet contains the majority of the components for a complete system. A typical PC frame or cabinet contains the following components: Backplane or motherboard for printed circuit boards A central processor unit (CPU) and memory printed circuit board(s) (pcb) (NOTE: In some cases the CPU and memory are located on the same pcb.) Input/output  pcb Disk controller pcb Video  controller  pcb Data storage devices: Hard disk drive units, floppy disk drive units, and/or tape cassette units I/O connector: Parallel or serial communica- tions A small fan: No special cooling require- ments; the unit relies on ambient temperature of the room or space Power supply: No special requirements Display monitors are output l Display  monitor — devices for visual displays of data, and may have monochrome or color displays. Figure  1-5.—Example  of  a  microcomputer. 1-6