Specifications

D-1
Appendix A
Glossary
A
A0–A15: Collectively, the external address bus; the 16 pins are used in par-
allel to address external data memory, program memory, or I/O space.
ACC: See accumulator.
ACCH: Accumulator high word. The upper 16 bits of the accumulator. See
also accumulator .
ACCL: Accumulator low word. The lower 16 bits of the accumulator. See
also accumulator .
accumulator: A 32-bit register that stores the results of operations in the
central arithmetic logic unit (CALU) and provides an input for subsequent
CALU operations. The accumulator also performs shift and rotate opera-
tions.
address: The location of program code or data stored in memory.
addressing mode: A method by which an instruction interprets its operands
to acquire the data it needs. See also
direct addressing ; immediate
addressing ; indirect addressing .
analog-to-digital (A/D) converter: A circuit that translates an analog signal
to a digital signal.
AR: See
auxiliary register .
AR0–AR7: Auxiliary registers 0 through 7. See auxiliary register .
ARAU: See auxiliary register arithmetic unit (ARAU).
ARB: See auxiliary register pointer buffer (ARB) .
ARP: See auxiliary register pointer (ARP).
auxiliary register: One of eight 16-bit registers (AR7–AR0) used as point-
ers to addresses in data space. The registers are operated on by the aux-
iliary register arithmetic unit (ARAU) and are selected by the auxiliary
register pointer (ARP).
Appendix D