MC68HC908MR8 Datasheet, PDF (360/372 Pages) Motorola, Inc – Microcontrollers

bit — A binary digit. A bit has a value of either logic 0 or logic 1.
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 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 clocks — There are two bus clocks, IT12 and IT23. These clocks are generated by the CGM
and distributed throughout the MCU by the SIM. The frequency of the bus clocks, or operating
frequency, is f_OP. While the frequency of these two clocks is the same, the phase is different.
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.
Technical Data
360
MC68HC908MR8 — Rev 4.1
Freescale Semiconductor