NEC PowerMate V486 Series Service Manual

Also see for POWERMATE V486 - SERVICE: Manual

Contents

Technical Information 1-15PCI BusThe industry-standard PCI bus is a highly-integrated input/output (I/O) interface that offersthe highest performance local bus available for the 486-based processor. The PCI bus sup-ports burst modes that send large chunks of data across the bus, allowing fast displays ofhigh-resolution images.The high-bandwidth PCI local bus eliminates data bottlenecks found in traditional systems,maintains maximum performance at high clock speeds, and provides a clear upgrade pathto future technologies.The PCI bus slot is used in conjunction with an ISA bus slot. This feature allows a PCI busoption board full access to the ISA bus. For example, the PCI bus option board may utilizethe parallel port via the ISA bus, or use the ISA bus REFRESH signal. Use of the ISA busis optional, as the PCI bus has all signals needed to fully support a PCI bus option board.PARALLEL INTERFACEThe system has a 25-pin parallel port on the system board. Specifications for this port con-form to the IBM-PC standards.The BIOS has automatic ISA printer port sensing. If the BIOS detects an ISA printer portmapped to the same address, the built-in printer port is disabled. The BIOS also sets thefirst parallel interface port it finds as LPT1 and the second port it finds as LPT2. The inter-rupt is set to IRQ5 via the Setup and jumper settings.Interrupt levels for the parallel port are given in Table Section 1-13. Software selectablebase addresses are 3BCh, 378h, and 278h.NOTE: Interrupts used for the built-in parallelport are not available for ISA parallel ports.Parallel interface signals are output through the system board's 25-pin, D-subconnector.The connector is located at the rear of the system unit. Pin locations for the parallel inter-face connector are shown in Appendix A.Table Section 1-13 Parallel Port Addressing and InterruptsStarting I/O Address Interrupt Level Port378 IRQ05 LPT1278 IRQ05 LPT1 or LPT23BC IRQ05 LPT1 or LPT2*Default for parallel port