MC68EC000EI12 Freescale Semiconductor, MC68EC000EI12 Datasheet - Page 26

• Manufacturer Part Number: MC68EC000EI12
• Description: IC MPU 32BIT 12MHZ 68-PLCC
• Manufacturer: Freescale Semiconductor
• Series: 68K - M680X0r

Specifications of MC68EC000EI12

• Processor Type: M680x0 32-Bit
• Speed: 12MHz
• Voltage: 3.3V, 5V
• Mounting Type: Surface Mount
• Package / Case: 68-PLCC
• Core Size: 32 Bit
• Cpu Speed: 12MHz
• Digital Ic Case Style: PLCC
• No. Of Pins: 68
• Supply Voltage Range: 3V To 3.6V
• Operating Temperature Range: 0°C To +70°C
• Filter Terminals: SMD
• Rohs Compliant: Yes
• Clock Frequency: 12MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -

1.5 FLOATING-POINT DATA FORMATS
The following paragraphs describe the FPU’s operand data formats. The FPU supports
seven data formats. There are three signed binary integer formats (byte, word, and long
word) that are identical to those supported by the integer unit. The FPU supports the use of
the packed decimal real format. The MC68881 and MC68882 support this format in
hardware and the processors starting with the MC68040 support it in software. The FPU
also supports three binary floating- point formats (single, double, and extended precision)
that fully comply with the IEEE 754 standard. All references in this manual to extended-
precision format imply the double-extended-precision format defined by the IEEE 754
standard.
1.5.1 Packed Decimal Real Format
Figure 1-11 illustrates the packed decimal real format which is three long words consisting
of a 3-digit base 10 exponent and a 17-digit base 10 mantissa. The first two long words,
digits 15 – 0, are 64 bits and map directly to bit positions 63 – 0 of the extended-precision
real format. There are two separate sign bits, one for the exponent, the other for the
mantissa. An extra exponent (EXP3) is defined for overflows that can occur when converting
from the extended-precision real format to the packed decimal real format.
MOTOROLA
Bit
Bit Field
Binary-Coded Decimal
(BCD)
Byte Integer
Word Integer
Long-Word Integer
Quad-Word Integer
16-Byte
Operand Data Format
M68000 FAMILY PROGRAMMER’S REFERENCE MANUAL
Table 1-3. Integer Data Formats
1 – 32 Bits
128 Bits
16 Bits
32 Bits
64 Bits
8 Bits
8 Bits
Size
1 Bit
Field of Consecutive Bit
Packed: 2 Digits/Byte; Unpacked: 1 Digit/Byte
Any Two Data Registers
Memory Only, Aligned to 16- Byte Boundary
Notes
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Introduction
1-15