M68ICS08GR datasheet(396/408 Pages) FREESCALE

396 / 408 page

Glossary

Technical Data

MC68HC908GR8 — Rev 4.0

396

Glossary

MOTOROLA

branch instruction — An instruction that causes the CPU to continue processing at a memory

location other than the next sequential address.

break module — A module in the M68HC08 Family. The break module allows software to halt

program execution at a programmable point in order to enter a background routine.

breakpoint — A number written into the break address registers of the break module. When a

number appears on the internal address bus that is the same as the number in the break

address registers, the CPU executes the software interrupt instruction (SWI).

break interrupt — A software interrupt caused by the appearance on the internal address bus

of the same value that is written in the break address registers.

bus — A set of wires that transfers logic signals.

bus clock — The bus clock is derived from the CGMOUT output from the CGM. The bus clock

frequency, fop, is equal to the frequency of the oscillator output, CGMXCLK, divided by

four.

byte — A set of eight bits.

C — The carry/borrow bit in the condition code register. The CPU08 sets the carry/borrow bit

when an addition operation produces a carry out of bit 7 of the accumulator or when a

subtraction operation requires a borrow. Some logical operations and data manipulation

instructions also clear or set the carry/borrow bit (as in bit test and branch instructions and

shifts and rotates).

CCR — See “condition code register.”

central processor unit (CPU) — The primary functioning unit of any computer system. The

CPU controls the execution of instructions.

CGM — See “clock generator module (CGM).”

clear — To change a bit from logic 1 to logic 0; the opposite of set.

clock — A square wave signal used to synchronize events in a computer.

clock generator module (CGM) — A module in the M68HC08 Family. The CGM generates a

base clock signal from which the system clocks are derived. The CGM may include a

crystal oscillator circuit and or phase-locked loop (PLL) circuit.

comparator — A device that compares the magnitude of two inputs. A digital comparator defines

the equality or relative differences between two binary numbers.

computer operating properly module (COP) — A counter module in the M68HC08 Family that

resets the MCU if allowed to overflow.

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M68ICS08GR Datasheet(PDF) 396 Page - Freescale Semiconductor, Inc