Glossary
Technical Data
MC68HC908AZ60A — Rev 2.0
446
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, f
op
, 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.
F
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
.