Compaq AlphaServer GS60 Operation Manual page 23

The TLSB bus is a synchronous bus (with a 256-bit data bus and a 40-bit
command/address bus) that interconnects processors, memory modules, and the I/O
port. The I/O port (KFTHA or KFTIA) module connects the TLSB bus to I/O buses
through separate I/O adapter modules.
The TLSB bus uses the concept of a node. The TLSB bus has three types of nodes:
processors, memories, and I/O port controllers.
A processor node is a single module. It consists of one or two scalar processors, the
shared TLSB bus interface, separate cache, and support logic.
In a multiprocessing system, one processor becomes the boot processor during power-
up, and that boot processor loads the operating system and handles communication
with the operator console. The other processors become secondary processors and
receive system information from the boot processor. The AlphaServer 8200 can have
up to three processor modules for a total of six CPUs. The AlphaServer 8400 can have
up to seven processor modules for a total of 14 CPUs.
A memory node is one memory module. Memory is a global resource equally
accessible by all processors on the TLSB. Memory modules can have 128, 256, or 512
Mbytes or 1, 2, or 4 Gbytes of memory with ECC and associated control logic. The
memories are automatically interleaved when the system is configured with multiple
memory banks. The 8200 system supports up to three memory modules; the 8400
supports up to seven.
The I/O port module (KFTHA) or integrated I/O module (KFTIA) provides the
interface between the TLSB and the I/O subsystem. The KFTHA provides
connections for up to four I/O buses using cables called hoses. For OpenVMS and
DIGITAL UNIX systems, these buses include the PCI/EISA, Futurebus+, or XMI
buses. For Windows NT, only PCI buses are supported. The KFTIA provides a
connection to one I/O subsystem, with the same possibilities for the operating system
as were noted for a KFTHA. In an 8200, only PCI buses are supported, regardless of
operating system.
In Figure 1–3, the I/O bus adapter can be the DWLPA/DWLPB module for the PCI,
the DWLAA module for the Futurebus+, and the DWLMA module for the XMI.
NOTE: The DWLPA is not supported with the Windows NT operating system; you
must have a DWLPB in this case.
The PCI I/O bus adapter module connects to various interconnects such as SCSI,
FDDI, Ethernet, NVRAM, and, with OpenVMS and DIGITAL UNIX systems, EISA
bus interfaces.
The Futurebus+ I/O bus adapter module connects to various interconnects such as
SCSI and FDDI.
The XMI I/O bus adapter module connects to various interconnects such as CI,
SDI/STI, SCSI, FDDI, and Ethernet..
Introduction 1-7