
Chapter 1. Overview
1-5
The signal groupings in Figure 1-2 are described in Table 1-1.
The evolution of the processors and the target market for the processors dictated that some
of these signals are not supported on some processors, have different pin counts, or may
operate differently on some processors. Those differences are described in Section 2.12,
“Summary of Signal Differences.”
Table 1-2 briefly describes each signal function and provides a reference to the detailed
description of the signal state meanings and timing considerations in Chapter 2, “Signal
Descriptions.”
Table 1-1. 60x Signal Groupings
Signal Group
Functionality
Address bus arbitration
Used to arbitrate for the address bus
Address transfer start
Indicate that the bus master has begun a transaction on the address bus
Address transfer
Used to transfer the address and to ensure the integrity of the transfer
Address transfer attribute
Provide information about the type of transfer
Address transfer termination
Indicate the end of the address phase or the need to repeat the address phase
Data bus arbitration
Used to arbitrate for the data bus mastership
Data transfer
Used to transfer the data and ensure the integrity of the transfer
Data transfer termination
Indicate the end of a data transfer or that the data phase should be repeated
System status
Indicate interrupts and system resets
Processor state
Used to manage the processor state
Power management
Provide a means for a processor and system to cooperate in power management
operations. The specific signals for each processor are identified in Table 1-2.
Table 1-2. Use and Reference for Bus Signals
Signal
I
O
Function
Application
Section
Basic L2 MP Opt.
Address Bus Arbitration Signals
Bus request (BR)
√
Requests mastership of the bus
√
2.1.1
Bus grant (BG)
√
Indicates bus ownership if properly qualified
√
2.1.2
Address bus busy (ABB)
√ √
Indicates whether the address bus is busy
√
2.1.3
2.1.4
Address Transfer Start Signals
Transfer start (TS)
√ √
Indicates that the master has begun a
transaction to memory
√
2.2.1
2.2.2
Extended transfer start
(XATS)
√ √
Indicates that the master has begun a
transaction to a direct-store address
√
2.2.3
2.2.4