MOTOROLA

MC68341 USER’S MANUAL ADDENDUM

9

25. Additional Note on PORTA/B Output Timing

Add to the External Bus Interface Operation description on page 4-17: The Port A and Port B output pins tran-

sition after the S4 falling edge for the internal write to the respective data register. This places port pin transi-

tions at roughly the same time DS negates for the data register write - note this output delay is not currently

specified in the Electrical Specifications.

26. RTC Memory Map

The RTC register offsets shown on page 4-21 are incorrect - a corrected memory map is shown below. Ad-

dresses within the RTC can be accessed as either bytes or words, with the exception of the reserved byte at

offset $0CE. Note that RTC registers marked S/U are read/write in supervisor mode, but can only be read in

user mode.

27. MBAR Register Reset Values

On page 4-22, the reset values for MBAR bits 31-12 are undefined.

28. MBAR AS7 Bit and IACK Cycles

On page 4-23, the second code sequence initializes the MBAR register with AS7 set. This prevents the ad-

dress decode for the internal 4K register block from responding to CPU space accesses. In particular, it pre-

vents the register block decode of $FFFFFxxx from interfering with IACK cycles (address $FFFFFFFx), and

possibly corrupting the vector number returned. Normal interrupt acknowledge operation for the internal mod-

ules is not affected by this change.

Early versions of the MC68330 User’s Manual (original release) and MC68340 User’s Manual (original and

Rev. 1 releases) did not show AS7 set. Code which was developed based on these manual revisions should

be checked for this problem when porting to the MC68341 - this change should also be applied back to the

MC68330 and/or MC68340.

29. Additional Note on VCO Overshoot

On page 4-30 place the following note under the Y-bits description:

ADDR

FC

15

8

ADDR

FC

7

0

0C0

S

RTC INTERRUPT CONTROL (RICR)

0C2

S/U

MINUTES (MIN)

0C3

S/U

SECONDS (SEC)

0C4

S/U

DATE

0C5

S/U

HOUR

0C6

S/U

MONTH

0C7

S/U

YEAR

0C8

S

RTC CONTROL/STATUS (RCR)

0C9

S/U

DAY

0CA

S/U

MINUTES ALARM (MINA)

0CB

S/U

SECONDS ALARM (SECA)

0CC

S/U

DATE ALARM (DATEA)

0CD

S/U

HOURS ALARM (HOURA)

0CE

-

RESERVED

0CF

S

RTC CALIBRATION (RCCR)