MC68EC000EI16 Freescale Semiconductor, MC68EC000EI16 Datasheet - Page 62

• Manufacturer Part Number: MC68EC000EI16
• Description: IC MPU 32BIT 16MHZ 68-PLCC
• Manufacturer: Freescale Semiconductor

Specifications of MC68EC000EI16

• Processor Type: M680x0 32-Bit
• Speed: 16MHz
• Voltage: 3.3V, 5V
• Mounting Type: Surface Mount
• Package / Case: 68-PLCC
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -

2.4 BRIEF EXTENSION WORD FORMAT COMPATIBILITY
Programs can be easily transported from one member of the M68000 family to another in
an upward-compatible fashion. The user object code of each early member of the family,
which is upward compatible with newer members, can be executed on the newer
microprocessor without change. Brief extension word formats are encoded with information
that allows the CPU32, MC68020, MC68030, and MC68040 to distinguish the basic M68000
family architecture’s new address extensions. Figure 2-3 illustrates these brief extension
word formats. The encoding for SCALE used by the CPU32, MC68020, MC68030, and
MC68040 is a compatible extension of the M68000 family architecture. A value of zero for
SCALE is the same encoding for both extension words. Software that uses this encoding is
compatible with all processors in the M68000 family. Both brief extension word formats do
not contain the other values of SCALE. Software can be easily migrated in an upward-
compatible direction, with downward support only for nonscaled addressing. If the MC68000
were to execute an instruction that encoded a scaling factor, the scaling factor would be
ignored and would not access the desired memory address. The earlier microprocessors do
not recognize the brief extension word formats implemented by newer processors. Although
they can detect illegal instructions, they do not decode invalid encodings of the brief
extension word formats as exceptions.
MOTOROLA
D/A
D/A
15
15
14
14
REGISTER
REGISTER
13
13
Figure 2-3. M68000 Family Brief Extension Word Formats
12
12
M68000 FAMILY PROGRAMMER’S REFERENCE MANUAL
(b) CPU32, MC68020, MC68030, and MC68040
W/L
W/L
11
11
(a) MC68000, MC68008, and MC68010
10
10
0
SCALE
9
0
9
8
0
8
0
7
7
6
6
DISPLACEMENT INTEGER
DISPLACEMENT INTEGER
5
5
4
4
Addressing Capabilities
3
3
2
2
1
1
2-21
0
0