MC68030CRC25C Freescale Semiconductor, MC68030CRC25C Datasheet - Page 471

• Manufacturer Part Number: MC68030CRC25C
• Description: IC MPU 32BIT ENHANCED 128-PGA
• Manufacturer: Freescale Semiconductor

Specifications of MC68030CRC25C

• Processor Type: M680x0 32-Bit
• Speed: 25MHz
• Voltage: 5V
• Mounting Type: Surface Mount
• Package / Case: 128-PGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -

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11-8
11.3.3 Average No-Cache Case
The nature of the instruction overlap and the fact that the heads of some
The average no-cache-case (NCC) time for an instruction takes into account
the time required for the microcode to execute plus the time required for all
external bus activity. This time is calculated assuming both caches miss and
the associated instruction prefetches require one external bus cycle per two
case time also assumes no overlap..All bus cycles are assumed to take two
clock periods. Average no-cache-case times for instructions and effective
address calculations are listed in 11.6 INSTRUCTION TIMING TABLES. Be-
cause the no-cache-case times assume no overlap, the head and tail values
listed in these tables do not apply to the no-cache-case values.
the value shown in the table is the average of the odd-word-aligned case
instructions equal the total instruction-cache-case time for those instructions
makes a zero net execution time possible. The execution time of an instruction
is completely absorbed by overlap with the previous instruction.
instruction prefetches. Refer to 11.2.2 Instruction Pipe. The average no-cache-
Since the actual no-cache-case time depends on the alignment of prefetches
associated with an instruction, both alignment cases were considered, and
and the even-word-aligned case (rounded up to an integral number of clocks).
Similarly, the number of prefetch bus cycles is the average of these two cases
rounded up to an integral number of bus cycles.
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HEAD
Figure 11-3. Derivation of Instruction Overlap Time
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MC68030 USER'S MANUAL
READ/WRITE BUS
TIME OR SYNC
/zC0DE TIME
CACHE CASE
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BEST CASE
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WRITE BUS TIME
TAIL
MOTOROLA
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