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1.1 How Does a Workstation Work?
• PCI ports – PCI ports (SBus ports on systems with SBus) are used for optional
peripherals (such as low-end and third party graphics controllers), a second SCSI
interface (also fast/wide SCSI is available), a second Ethernet interface, extra serial
and parallel I/O ports, and ISDN ports. Even PC coprocessors are available on SBus
or PCI cards. Most systems come with several such expansion ports.
• ISDN port – An ISDN port is included on SPARCstation 10 systems only, for data
connections over digital telephone networks.
EBus
On current Ultra workstations, lower- and medium-speed I/O is done via dedicated EBus
(external bus) interface, which connects several facilities built into the CPU board. On
SPARCstations, these facilities are connected to the SBus as well.
• EIDE disk controller – Lower end Ultra workstations (Ultra 5, Ultra 10) are equipped
with 1 or 2 EIDE disks.
• Floppy disk controller – Needed for an optional internal floppy disk drive (1.44 MB).
• Parallel I/O controller with Centronics port – Typically used for printers/plotters.
• Serial I/O controller – Used with two RS-423 (RS-232 compatible) serial ports for
external peripherals, such as printers and plotters, plus two internal ports used for the
keyboard and the mouse.
• Audio I/O controller – For driving the built-in loudspeaker (optional on some systems)
and taking input from a microphone port.
• NVRAM, TOD – On Ultra workstations, nonvolatile RAM (NVRAM; EEPROMS on
earlier workstations) and the real-time clock (TOD) are accessed via the EBus.
Other CPU Board Components
The CPU board contains additional components less visible to the user, such as PROMs
containing diagnostics software and system bootup utilities, an EEPROM (nonvolatile
memory, NVRAM) for storing system configuration parameters, and quartz oscillators that
generate the operating frequencies for some of the components. Unless the CPU box is
open, the user can usually only access the connectors for the peripherals on the front of the
CPU board.
On some systems, there is not enough space for all the connections along the front of the
CPU board. In these cases, some connectors combine two ports, in which case one of the
two functions is only available via a special “V-shaped” branch cable. Some SPARCstation
models have two serial ports combined in one V.24 connector, and some combine the AUI
Ethernet and audio ports in a single connector.
SCSI Bus
The SCSI bus is a linear chain that has a maximum total length of about 5 meters by its
electrical definition, including all internal cabling. The SCSI bus must be terminated at the
remote end to work properly. With desktop storage modules, a terminator plug must be
plugged into the second connector of the last module in the chain. The newer Unipack
modules are self-terminating—a termination plug is no longer necessary. SCSI devices can
be connected in any order (with certain very specific exceptions as discussed below).
01-999166-00 C0503
System Administration
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