Signal Description
2-2
M68060 USER’S MANUAL
MOTOROLA
Transfer Retry Acknowl-
edge
TRA
Indicates the need to rerun the bus cycle.
Transfer Error Acknowl-
edge
TEA
Indicates an error condition exists for a bus transfer.
Transfer Cycle Burst In-
hibit
TBI
Indicates the slave cannot handle a line burst access.
Transfer Cache Inhibit
TCI
Indicates the current bus transfer should not be cached.
Snoop Control
SNOOP
Indicates the MC68060 should snoop bus activity while it is not the bus master.
Bus Request
BR
Asserted by the processor to request bus mastership.
Bus Grant
BG
Asserted by an arbiter to grant bus mastership privileges to the processor.
Bus Grant Relinquish
Control
BGR
Qualifies BG by indicating the degree of necessity for relinquishing bus owner-
ship when BG is negated.
Bus Tenure Termination
BTT
Indicates the MC68060 has relinquished the bus in response to the external ar-
biter’s negation of BG.
Bus Busy
BB
Asserted by the current bus master to indicate it has assumed ownership of the
bus.
Cache Disable
CDIS
Dynamically disables the internal caches to assist emulator support.
MMU Disable
MDIS
Disables the translation mechanism of the MMUs.
Reset In
RSTI
Processor reset.
Reset Out
RSTO
Asserted during execution of a RESET instruction to reset external devices.
Interrupt Priority Level
IPL2–IPL0
Provides an encoded interrupt level to the processor.
Interrupt Pending
IPEND
Indicates an interrupt is pending.
Autovector
AVEC
Used during an interrupt acknowledge transfer to request internal generation of
the vector number.
Processor Status
PST4–PST0 Indicates internal processor status.
Processor Clock
CLK
Clock input used for all internal logic timing.
Clock Enable
CLKEN
Defines the speed of the system bus clock to be full, 1/2, or 1/4 the speed of the
processor clock.
JTAG Enable
JTAG
Selects between IEEE 1149.1 compliance operation and emulation mode oper-
ation.
Test Clock
TCK
Clock signal for the IEEE P1149.1 test access port (TAP).
Test Mode Select
TMS
Selects the principal operations of the test-support circuitry.
Test Data Input
TDI
Serial data input for the TAP.
Test Data Output
TDO
Serial data output for the TAP.
Test Reset
TRST
Provides an asynchronous reset of the TAP controller.
Thermal Resistor Con-
nections
THERM1,
THERM0
Provides thermal sensing information.
Power Supply
VCC
Power supply.
Ground
GND
Ground connection.
Table 2-1. Signal Index (Continued)
Signal Name
Mnemonic
Function