80960JD datasheet(68/78 Pages) INTEL

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80960JA/JF/JD/JT 3.3 V Microprocessor

Advance Information Datasheet

5.1

Basic Bus States

The bus has five basic bus states: idle (Ti), address (Ta), wait/data (Tw/Td), recovery (Tr), and hold

(Th). During system operation, the processor continuously enters and exits different bus states.

The bus occupies the idle (Ti) state when no address/data transactions are in progress and when RESET is

asserted. When the processor needs to initiate a bus access, it enters the Ta state to transmit the address.

Following a Ta state, the bus enters the Tw/Td state to transmit or receive data on the address/data

lines. Assertion of the RDYRCV input signal indicates completion of each transfer. When data is

not ready, the processor can wait as long as necessary for the memory or I/O device to respond.

After the data transfer, the bus exits the Tw/Td state and enters the recovery (Tr) state. In the case of a

burst transaction, the bus exits the Td state and re-enters the Td/Tw state to transfer the next data word.

The processor asserts the BLAST signal during the last Tw/Td states of an access. Once all data words

transfer in a burst access (up to four), the bus enters the Tr state to allow devices on the bus to recover.

The processor remains in the Tr state until RDYRCV is deasserted. When the recovery state

completes, the bus enters the Ti state if no new accesses are required. If an access is pending, the

bus enters the Ta state to transmit the new address.

Figure 43.

Bus States with Arbitration

Ti — IDLE STATE

Ta — ADDRESS STATE

Tw / Td — WAIT/DATA STATE

Tr — RECOVERY STATE

Th — HOLD STATE

To — ONCE STATE

READY — RDYRCV ASSERTED

NOT READY — RDYRCV NOT ASSERTED

BURST — BLAST NOT ASSERTED

NO BURST — BLAST ASSERTED

RECOVERED — RDYRCV NOT ASSERTED

NOT RECOVERED — RDYRCV ASSERTED

REQUEST PENDING — NEW TRANSACTION

NO REQUEST

— NO NEW TRANSACTION

HOLD — HOLD REQUEST ASSERTED

NO HOLD — HOLD REQUEST NOT ASSERTED

LOCKED — ATOMIC EXECUTION (ATADD, ATMOD) IN PROGRESS

NOT LOCKED — NO ATOMIC EXECUTION IN PROGRESS

RESET — RESET ASSERTED

ONCE — ONCE ASSERTED

Tw/Td

HOLD AND

NOT LOCKED

HOLD

RECOVERED AND

NO REQUEST AND

(NO HOLD OR

LOCKED)

RECOVERED AND

REQUEST

PENDING AND (NO

HOLD OR LOCKED)

NO REQUEST

AND NO HOLD

RESET

NOT

RECOVERED

RECOVERED AND

HOLD AND NOT

LOCKED

READY AND NO BURST

(READY AND BURST)

OR NOT READY

REQUEST PENDING

AND (NO HOLD OR

LOCKED)

NO REQUEST

AND (NO HOLD

OR LOCKED)

ONCE & RESET

DEASSERTION

REQUEST

PENDING AND

NO HOLD

80960JD Datasheet(PDF) 68 Page - Intel Corporation

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