MC68030 Datasheet, PDF (491/602 Pages) Motorola, Inc – ENHANCED 32-BIT MICROPROCESSOR

Instruction Execution Timing
(UNABLE TO LOCATE ART)
The following table gives some sample times obtained using the shell script. Each row of the
table indicates a translation table configuration. The identifier on each row consists of five
positions. Each position may have either an "x", meaning that there is no table at the level;
an "S", meaning that the table at the level is composed of short-format descriptors; or an "L",
meaning that the table at the level is composed of long-format descriptors. The format of the
entries is:
FUNCTION CODE TABLE
LEVEL A TABLE
LEVEL B TABLE
LEVEL C TABLE
LEVEL D TABLE
XX / XX / XX / XX / XX
Each entry in the table consists of three numbers that give the number of clock cycles, the
number of bus reads, and the number of bus writes required for a table search. An RMC
cycle to set the U bit is counted as one read and one write. The format of the entires is:
NUMBER OF CLOCK CYCLES
NUMBER OF READ BUS CYCLES
NUMBER OF WRITE BUS CYCLES
XX / XX / XX
The table is calculated based on the following assumptions:
1. Bus cycle time is two clock cycles,
2. There are no indirect descriptors,
3. There are no page descriptors encountered unexpectedly (no early termination), and
4. The memory port is 32 bits wide.
Table
Format
LLxxx
LLLxx
LLLLx
LLLLL
SSxxx
SSSxx
SSSSx
SSSSS
xSSxx
All U and M Bits
Must be Set
41/4/2
53/6/3
65/8/4
77/10/5
37/2/2
46/3/3
55/4/4
64/5/5
39/2/2
Page U and M Bits
Only Must be Set
37/4/1
45/6/1
53/8/1
61/10/1
33/2/1
38/3/1
43/4/1
48/5/1
35/2/1
No U and M Bits
Must be Set
35/4/0
43/6/0
51/8/0
59/10/0
31/2/0
36/3/0
41/4/0
46/5/0
33/2/0
11-56
MC68030 USER’S MANUAL
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