SUMMARY—FUNDAMENTALS AND OPERATIONS OF COMPUTERS

tests and operating practices for EMI reduction. MIL-STD-1310 entitled Shipboard Bonding, Grounding, and Other Techniques for Electromagnetic Compatibility and Safety, is a military standard for the proper instruction of bonding straps and grounding cables. It is the reference for all shipboard electromagnetic capability (EMC) installations. It contains drawings that depict the proper shape of and lists materials required to construct bonding straps and grounding leads for shipboard electrical/electronics installation. The Naval Shore Electronics Criteria handbook, Electromagnetic Radiation Hazards, NAVSEA OP 3565 Volumes 1 and 2, (parts 1 and 2) (NAVELEX 0967-LP-624-6010) has information on the reduction of EMI at shorebased facilities. All facets of grounding, shielding, and equipment bonding are contained in this highly informative handbook. The Handbook of Shipboard Electromagnetic Shielding Practices, NAVSEA S9407-AB-HBK-010, provides specifications for cable spacing/shielding requirements and installation procedures that will minimize the effects of electromagnetic interference (EMI) on electronic equipment installed in naval vessels. It is intended for use by ship designers, planning engineers, personnel engaged in the installation of electronic equipment, overhaul and repair shipyards, tenders, and other repair and installation activities. SUMMARY—FUNDAMENTALS AND OPERATIONS OF COMPUTERS This chapter has introduced you to computer functions, types of computers (mainframe computers, minicomputers, and microcomputers), operational uses, modes of operation, capabilities and limitations, and operational requirements. The following information summarizes important points you should have learned: COMPUTER FUNCTIONS —Computers gather, process, store, disseminate, and display data. Data may be gathered manually or automatically or by a combination of both. Once processed, it can be stored either internally in memory banks or extemally on disk or tape. Data maybe disseminated and stored, or it may be sent to a display device. MAINFRAME COMPUTERS —Mainframe computers are large computers. Those used aboard Navy vessels are designed for ruggedness and are general-purpose, digital data computers with multiprocessing capability. They usually have operator and remote consoles and a maintenance panel/display control unit (DCU). They have specific power and cooling requirements. MINICOMPUTERS —Minicomputers are mid- range computers. They are capable of stand-alone (self-contained) operation, or they maybe an embedded processor in a system or other type of digital device. They usually have a control and maintenance panel (CMP) or computer control panel. Like the mainframe, they have a rugged frame when used aboard ship, and they have specific power and cooling requirements. MICROCOMPUTERS —Microcomputers (per- sonal computers) are small, lightweight computers. Their central processing unit is contained on a single integrated chip (IC) and the entire computer system is contained on a handful of printed circuit boards in a small compact frame or cabinet. FUNCTIONAL OPERATION OF COM- PUTERS —Computers exchange data with other computers, peripherals, and subsystems through a coordinated series of interrupts, requests, and acknowledges. The signal flow is coordinated by the operational program. INTERFACING —Interfacing between the computer and other systems, subsystems, and equipment includes cabling and associated connectors. Methods of interfacing include both parallel and serial data transfers. OPERATIONAL USES —Operational uses of computers include tactical and Naval Tactical Command Support Systems. COMPUTER SYSTEM CONFIGURA- TIONS —Each system must be configured for operation and maintenance. The hardware and software must be compatible and must be set up to work together. MODES OF OPERATION —Computer systems may be operated in online, offline, and battle short modes. Maintenance may be performed online if there is enough memory; otherwise it will be performed offline. Battle short mode is used when it is necessary to run the system continuously even though an overtemperature condition exists. OPERATIONAL SYSTEM REQUIRE- MENTS —The operational capabilities and limitations can be controlled at the equipment, or through switchboards, control panels, or commands to the software. Effective operation depends on adherence to 1-16