COP8-NSDEV datasheet(9/83 Pages) NSC

9 / 83 page

6.0 Architectural Overview (Continued)

examples. In many cases, the instruction set can simulta-

neously execute as many as three functions with the same

single-byte instruction.

JID: (Jump Indirect); Single byte instruction decodes exter-

nal events and jumps to corresponding service routines

(analogous to “DO CASE” statements in higher level lan-

guages).

LAID: (Load Accumulator-Indirect); Single byte look up table

instruction provides efficient data path from the program

memory to the CPU. This instruction can be used for table

lookup and to read the entire program memory for checksum

calculations.

RETSK: (Return Skip); Single byte instruction allows return

from subroutine and skips next instruction. Decision to

branch can be made in the subroutine itself, saving code.

AUTOINC/DEC: (Auto-Increment/Auto-Decrement); These

instructions use the two memory pointers B and X to effi-

ciently process a block of data (simplifying “FOR NEXT” or

other loop structures in higher level languages).

6.6.4 Bit-Level Control

Bit-level control over many of the microcontroller’s I/O ports

provides a flexible means to ease layout concerns and save

board space. All members of the COP8 family provide the

ability to set, reset and test any individual bit in the data

memory address space, including memory-mapped I/O ports

and associated registers.

6.6.5 Register Set

Three memory-mapped pointers handle register indirect ad-

dressing and software stack pointer functions. The memory

data pointers allow the option of post-incrementing or post-

decrementing with the data movement instructions (LOAD/

EXCHANGE). And 15 memory-mapped registers allow de-

signers to optimize the precise implementation of certain

specific instructions.

6.7 PACKAGING/PIN EFFICIENCY

Real estate and board configuration considerations demand

maximum space and pin efficiency, particularly given today’s

high integration and small product form factors. Microcon-

troller users try to avoid using large packages to get the I/O

needed. Large packages take valuable board space and

increases device cost, two trade-offs that microcontroller

designs can ill afford.

The COP8 family offers a wide range of packages and does

not waste pins: up to 85.7% are devoted to useful I/O.

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