MC68EC000EI8 Freescale Semiconductor, MC68EC000EI8 Datasheet - Page 27

• Manufacturer Part Number: MC68EC000EI8
• Description: IC MPU 32BIT 85MHZ 68-PLCC
• Manufacturer: Freescale Semiconductor
• Series: M68000r

Specifications of MC68EC000EI8

• Processor Type: M680x0 32-Bit
• Speed: 8MHz
• Voltage: 3.3V, 5V
• Mounting Type: Surface Mount
• Package / Case: 68-PLCC
• Core Size: 32 Bit
• Cpu Speed: 8MHz
• 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: 8MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -

Introduction
1.5.2 Binary Floating-Point Formats
Figure 1-12 illustrates the three binary floating-point data formats. The exponent in the three
binary floating-point formats is an unsigned binary integer with an implied bias added to it.
When subtracting the bias from the exponent’s value, the result represents a signed twos
complement power of two. This yields the magnitude of a normalized floating-point number
when multiplied by the mantissa. A program can execute a CMP instruction that compares
floating-point numbers in memory using biased exponents, despite the absolute magnitude
of the exponents.
Data formats for single- and double-precision numbers differ slightly from those for
extended-precision numbers in the representation of the mantissa. For all three precisions,
a normalized mantissa is always in the range (1.0...2.0). The extended-precision data format
represents the entire mantissa, including the explicit integer part bit. Single- and double-
precision data formats represent only a fractional portion of the mantissa (the fraction) and
always imply the integer part as one.
1-16
S
94
EXPONENT
SIGN OF MANTISSA
15-BIT
NOTE: XXXX indicates “don't care", which is zero when written and ignored when
96
SM
32
DIGIT 15
DIGIT 7
SE
80
M68000 FAMILY PROGRAMMER’S REFERENCE MANUAL
Figure 1-12. Binary Floating-Point Data Formats
Y Y
read.
ZERO
Figure 1-11. Packed Decimal Real Format
DIGIT 14
DIGIT 6
EXP 0
SIGN OF MANTISSA
SIGN OF EXPONENT
USED ONLY FOR ± INFINITY OR NANS
63
S
62
DIGIT 13
DIGIT 5
EXPONENT
EXP 1
EXPLICIT INTEGER PART BIT
SIGN OF FRACTION
11-BIT
DIGIT 12
DIGIT 4
EXP 0
51
.
.
DIGIT 11
DIGIT 3
(EXP 3)
MANTISSA
64-BIT
S
30
FRACTION
EXPONENT
IMPLICIT DECIMAL POINT
52-BIT
DIGIT 10
DIGIT 2
SIGN OF FRACTION
XXXX
8-BIT
22
DIGIT 9
DIGIT 1
XXXX
FRACTION
23-BIT
DIGIT 16
DIGIT 8
DIGIT 0
0
0
0
SINGLE REAL
DOUBLE REAL
EXTENDED REAL
65
0
MOTOROLA