C161U
Architectural Overview
Preliminary Data Sheet
34
02.2000
PRELIMINARY
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The high performance offered by the hardware implementation of the CPU can efficiently
be utilized by a programmer via the highly functional C161U instruction set which
includes the following instruction classes:
Arithmetic Instructions
Logical Instructions
Boolean Bit Manipulation Instructions
Compare and Loop Control Instructions
Shift and Rotate Instructions
Prioritize Instruction
Data Movement Instructions
System Stack Instructions
Jump and Call Instructions
Return Instructions
System Control Instructions
Miscellaneous Instructions
Possible operand types are bits, bytes and words. Specific instruction support the
conversion (extension) of bytes to words. A variety of direct, indirect or immediate
addressing modes are provided to specify the required operands.
Programmable Multiple Priority Interrupt System
The following enhancements have been included to allow processing of a large number
of interrupt sources:
1)Peripheral Event Controller (PEC): This processor is used to off-load many interrupt
requests from the CPU. It avoids the overhead of entering and exiting interrupt or trap
routines by performing single-cycle interrupt-driven byte or word data transfers with an
optional increment of either the PEC source or the destination pointer. Just one cycle is
'stolen' from the current CPU activity to perform a PEC service.
2)Multiple Priority Interrupt Controller: This controller allows all interrupts to be placed at
any specified priority. Interrupts may also be grouped, which provides the user with the
ability to prevent similar priority tasks from interrupting each other. For each of the
possible interrupt sources there is a separate control register, which contains an interrupt
request flag, an interrupt enable flag and an interrupt priority bitfield. Once having been
accepted by the CPU, an interrupt service can only be interrupted by a higher prioritized
service request. For standard interrupt processing, each of the possible interrupt sources
has a dedicated vector location.