NEC POWERMATE ES 5200 - SERVICE, Service Manual

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4-12 System Board
ISA Bus
The system board uses the ISA bus for transferring data between the processor
and some I/O peripherals and expansion boards. The ISA bus supports 16-bit
data transfers and typically operates at 8 MHz.
PCI Local Bus
The 32-bit PCI local bus is the primary I/O bus for the system. The PCI bus is a
highly integrated I/O interface that offers the highest performance local bus
available for the Pentium processor. The bus supports burst modes that send
large amounts of data across the bus, allowing fast displays of high-resolution
images.
The PCI local bus is a high-performance bus that provides a processor-
independent data path between the CPU and high-speed peripherals. The PCI
bus is a robust interconnect mechanism designed specifically to accommodate
multiple high performance peripherals for graphics, full motion video, SCSI,
and LAN.
The PCI local bus supports memory transfer rates of over 100 MB per second
for reads and over 120 MB per second for writes, depending on processor
configuration.
PCI/IDE Ports
The system board supports two high-performance PCI/IDE ports: a primary port
and a secondary port (the port connectors are located on the riser board, which
plugs into the system board). Each port supports up to two devices for a total of
four IDE devices (although the number of devices the system can house depends
on how many bays there are in the chassis and the capacity of the power
supply). The primary PCI/IDE port has an enhanced IDE interface that supports
PIO Mode 4 devices with 16 MB per second 32-bit wide data transfers on the
high-performance PCI local bus. Each port supports Ultra DMA/33.
The installed hard drive is connected to the primary PCI/IDE connector with a
three-connector cable. If a CD-ROM drive is included in the system, it is
connected to the secondary PCI/IDE port with a three-connector cable. A second
device can be added to the primary PCI/IDE port.
Parallel Interface
The system has a 25-pin bi-directional parallel port on the system board. Port
specifications conform to the IBM-PC standards. The port supports Enhanced
Capabilities Port (ECP) and Enhanced Parallel Port (EPP) modes for devices
that require ECP or EPP protocols. The protocols allow high-speed bi-
directional transfer over a parallel port and increase parallel port functionality
by supporting more devices.