80960CF-40 Datasheet, PDF (14/77 Pages) Intel Corporation – 80960CF-40, -33, -25, -16 32-BIT HIGH-PERFORMANCE SUPERSCALAR EMBEDDED MICROPROCESSOR

80960CF-40, -33, -25, -16
A
Name
HOLDA
BREQ
D/C
DMA
SUP
Table 2. 80960CF Pin Description — External Bus Signals (Sheet 3 of 3)
Type
O
S
H(1)
R(Q)
O
S
H(Q)
R(0)
O
S
H(Z)
R(Z)
O
S
H(Z)
R(Z)
O
S
H(Z)
R(Z)
Description
HOLD ACKNOWLEDGE indicates to a bus requestor that the processor has relin-
quished control of the external bus. When HOLDA is asserted, the external address
bus, data bus and bus control signals are floated. HOLD, BOFF, HOLDA and BREQ are
used together to arbitrate access to the processor’s external bus by external bus
agents. Since the processor grants HOLD requests and enters the Hold Acknowledge
state even while RESET is asserted, the state of the HOLDA pin is independent of the
RESET pin.
BUS REQUEST is asserted when the bus controller has a request pending. BREQ can
be used by external bus arbitration logic in conjunction with HOLD and HOLDA to deter-
mine when to return mastership of the external bus to the processor.
DATA OR CODE is asserted for a data request and deasserted for instruction requests.
D/C has the same timing as W/R.
DMA ACCESS indicates whether the bus request was initiated by the DMA controller.
DMA is asserted for any DMA request. DMA is deasserted for all other requests.
SUPERVISOR ACCESS indicates whether the bus request is issued while in super-
visor mode. SUP is asserted when the request has supervisor privileges and is
deasserted otherwise. SUP can be used to isolate supervisor code and data structures
from non-supervisor requests.
8
PRELIMINARY