Typewriter User Manual

MOTOROLA MC68340 USER’S MANUAL 3- 37

S0 S2 S0 S2SW S4SW S4

READ RERUNHALTREAD CYCLE WITH

RETRY

DATA

IGNORED

CLKOUT

DSACKx

R/W

BERR

A31–A0

FC3–FC0

D15–D0

HALT

Figure 3-19. Retry Sequence

The MC68340 retries any read or write cycle of a read-modify-write operation separately;

RMC remains asserted during the entire retry sequence. Asserting BR along with BERR

and HALT provides a relinquish and retry operation. The MC68340 does not relinquish the

bus during a read-modify-write operation. Any device that requires the MC68340 to give

up the bus and retry a bus cycle during a read-modify-write cycle must assert only

BERR

and BR (HALT must not be included). The bus error handler software should examine the

read-modify-write bit in the special status word (see Section 5 CPU32) and take the

appropriate action to resolve this type of fault when it occurs.

Frees

cale Semiconductor,

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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