3-5
Themis Computer
3—Hardware Overview
Baseboard
Among the features of the 21154 are a programmable 2-level secondary bus arbiter,
an IEEE standard 1149.1 JTAG interface, live insertion support, a 4-pin general-pur-
pose I/O interface, individual secondary clock disables, and enhanced address
decoding. The 21154 has enough clock and arbitration pins to support nine PCI bus
master devices directly on its secondary interface.
The 21154 allows the two PCI buses to operate concurrently. This means that a mas-
ter and a target on the same PCI bus can communicate while the other PCI bus is
busy. This traffic isolation increases system performance.
3.1.4
Sun Rio I/O Controller
Sun's Rio I/O controller (SME2300) incorporates an Ethernet interface, USB, and an
Ebus interface. The Ethernet port autosenses the port speed as either 10 or 100
Mbit/sec, with no pin-jumpers required to set either rate.
The Ebus supports the NVRAM, boot flash, user flash 0, 1, and 2, system PLD, and
DUART (dual UART). The DUART controls both TTYC (RS232) and TTYD
(RS232) serial ports.
3.1.5
Symbios SCSI Controller
The Symbios SCSI Controller (SYM53C896) provides two (2) LVD UltraWide
SCSI-3 interfaces (80 MB/sec). In order to maximize speed, it is attached directly to
the 33-MHz/64-bit PCI bus connected to the Intel 21154 PCI-to-PCI bridge. A max-
imum burst rate of up to 264 MB/sec is supported.
3.1.6
Tundra Universe II
The Tundra Universe II (Tundra CA91C142B) ASIC interfaces the local 32-bit PCI
bus to the 64-bit VMEbus. The Universe II includes a 33-MHz, 32-bit PCI bus inter-
face, a fully compliant, high-performance, 64-bit VMEbus interface, as well as a
broad range of VMEbus address and data transfer modes of:
• A32/A24/A16 master and slave transfer, except for A64 and A40
• D64/D32/D16/D08 master and slave transfer, except for MD32
• MBLT, BLT, ADOH, RMW, LOCK, and location monitors
The Universe II also includes support for full VMEbus System Controller, eight
user-programmable slave images, and seven interrupt lines. For more information on
the Universe II, refer to Chapter 4, "Universe II Description" and the
Tundra Uni-
verse II User Manual
(Tundra 8091142.MD300.01).
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