MC68EC000EI12 Freescale Semiconductor, MC68EC000EI12 Datasheet - Page 404

• 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: -

Floating Point Instructions
FNOP
Operation:
Assembler
Syntax:
Attributes:
Description: This instruction does not perform any explicit operation. However, it is useful
Floating-Point Status Register: Not Affected.
5-102
to force synchronization of the floating- point unit with an integer unit or to force
processing of pending exceptions. For most floating-point instructions, the integer unit
is allowed to continue with the execution of the next instruction once the floating-point
unit has any operands needed for an operation, thus supporting concurrent execution
of floating-point and integer instructions. The FNOP instruction synchronizes the
floating-point unit and the integer unit by causing the integer unit to wait until all
previous floating-point instructions have completed. Execution of FNOP also forces
any exceptions pending from the execution of a previous floating-point instruction to be
processed as a preinstruction exception.
The MC68882 may not wait to begin execution of another floating- point instruction until
it has completed execution of the current instruction. The FNOP instruction synchro-
nizes the coprocessor and microprocessor unit by causing the microprocessor unit to
wait until the current instruction (or both instructions) have completed.
The FNOP instruction also forces the processing of exceptions pending from the exe-
cution of previous instructions. This is also inherent in the way that the floating-point
coprocessor utilizes the M68000 family coprocessor interface. Once the floating-point
coprocessor has received the input operand for an arithmetic instruction, it always
releases the main processor to execute the next instruction (regardless of whether or
not concurrent execution is prevented for the instruction due to tracing) without report-
ing the exception during the execution of that instruction. Then, when the main proces-
sor attempts to initiate the execution of the next floating-point coprocessor instruction,
a preinstruction exception may be reported to initiate exception processing for an
exception that occurred during a previous instruction. By using the FNOP instruction,
the user can force any pending exceptions to be processed without performing any
other operations.
M68000 FAMILY PROGRAMMER’S REFERENCE MANUAL
None
FNOP
Unsized
(MC6888X, MC68040)
No Operation
FNOP
MOTOROLA