Specifications

Glossary
D-3 Glossary
C
C bit: See carry bit.
CALU: See central arithmetic logic unit (CALU).
carry bit: Bit 9 of status register ST1; used by the CALU for extended
arithmetic operations and accumulator shifts and rotates. The carry bit
can be tested by conditional instructions.
central arithmetic logic unit (CALU): The 32-bit wide main arithmetic logic
unit for the ’24x CPU that performs arithmetic and logic operations. It
accepts 32-bit values for operations, and its 32-bit output is held in the
accumulator.
CLKIN:
Input clock signal . A clock source signal supplied to the on-chip
clock generator at the CLKIN/X2 pin or generated internally by the
on-chip oscillator. The clock generator divides or multiplies CLKIN to
produce the CPU clock signal, CLKOUT.
CLKOUT:
Master clock output signal . The output signal of the on-chip clock
generator. The CLKOUT high pulse signifies the CPU’s logic phase
(when internal values are changed), and the CLKOUT low pulse signifies
the CPU’s latch phase (when the values are held constant).
CNF bit: DARAM configuration bit . Bit 12 in status register ST1. CNF is used
to determine whether the on-chip RAM block B0 is mapped to program
space or data space.
codec: A device that codes in one direction of transmission and decodes in
another direction of transmission.
COFF:
Common object file format. A system of files configured according to
a standard developed by AT&T. These files are relocatable in memory
space.
context saving/restoring: Saving the system status when the device
enters a subroutine (such as an interrupt service routine) and restoring
the system status when exiting the subroutine. On the ’24x, only the pro-
gram counter value is saved and restored automatically; other context
saving and restoring must be performed by the subroutine.
CPU:
Central processing unit . The ’24x CPU is the portion of the processor
involved in arithmetic, shifting, and Boolean logic operations, as well as
the generation of data- and program-memory addresses. The CPU
includes the central arithmetic logic unit (CALU), the multiplier, and the
auxiliary register arithmetic unit (ARAU).