Brief Description Of The Tlsb Bus; Command/Address Bus - Compaq AlphaServer GS60E Service Manual

4.1

Brief Description of the TLSB Bus

The error log entries discussed here are specific to the AlphaServer
GS60E system. Most of the errors occur during the transmission of
commands or data along the TLSB system bus or in buses or storage
internal to a particular module.
To understand some of the terms used in the error log, you should understand
how data is transferred on the TLSB system bus. The TLSB has two separate
buses: a command/address bus and a data bus. Thus, errors can refer to
transmissions on either of these buses.
A node that initiates a transaction is called a commander node. The node that
responds to the command issued by the commander is called the slave node.
CPUs or I/O nodes are always the commander on memory transactions and can
be either the commander or the slave on CSR (control and status register)
transactions. Memory nodes are never commander nodes.
4.1.1

Command/Address Bus

Table 4-1 lists the eight address bus commands.
Table 4–1 TLSB Address Bus Commands
TLSB CMD
<2:0> Command
000 No-op
001 Victim
010 Read
011 Write
100 Read Bank Lock
101 Write Bank Lock
110 CSR Read
111 CSR Write
4-2 Service Manual
Description
Device that won arbitration nulled the
command
Victim
Read memory
Memory write or write update
Read memory bank, lock
Write memory bank, unlock
Read CSR data
Write CSR data