eZ80
®
CPU
User Manual
UM007714-0908 Glossary
384
Bit Error Ratio Tester (BERT). A testing device that compares a received data pattern with a known
transmitted pattern to determine the level of transmission quality.
bit configuration. The sequence of bits used to encode a character.
bit inversion. The changing of the state of a bit to the opposite state. The changing of the state that
represents a given bit, i.e., a 0 or a 1, to the opposite state.
bit rate (BR). In a bit stream, the number of bits occurring per unit time, usually expressed in bits per
second.
bit string. A sequence of bits. In a bit stream, individual bit strings may be separated by data delimiters.
bps. bits per second—the number of binary digits transmitted every second during a data-transfer
procedure.
BR. See Bit Rate.
BRG. Baud Rate Generator.
BUSACK. Bus Acknowledge—a message granting permission for a device to transfer data on the bus.
BUSREQ. Bus Request—a message from a device requesting permission to transfer data on the bus.
byte (B). A sequence of adjacent bits (usually 8) considered as a unit. A collection of four sequential bits
of memory. Two sequential bytes (8 bits) comprise one word.
C. Carry.
CALL. Call Subroutine; a program control instruction.
CALL cc. Conditional Call Subroutine; a program control instruction.
Carry Flag. The Carry Flag bit is set or reset depending on the operation performed, such as an
ADD
, which can generate a carry, or a
SUBTRACT
, which can generate a borrow. CCF. Clear
Carry Flag. Complement Carry Flag; a processor control instruction.
CE. Chip Enable.
C.
See Carry Flag.
check bit.
A bit, such as a parity bit, derived from and appended to a bit string for later use in error
detection and possibly error correction.
checksum. A field of one or more bytes appended to a block of n words that contain a truncated binary
sum formed from the contents of that block. The sum is used to verify the integrity of data in a ROM or on
a tape.
CIEF. Clear IE Flag.
clock rate. The rate at which a clock issues timing pulses.
CLR. Clear.
comparator. In analog computing, a functional unit that compares two analog variables and indicates the
result of that comparison. A device that compares two items of data and indicates the result of that
comparison. A device for determining the dissimilarity of two items such as two pulse patterns or words.
CP. Compare with Accumulator; an arithmetic instruction.
CPD (CPDR). Compare and Decrement (with Repeat); a compare instruction.
CPI (CPIR). Compare and Increment (with Repeat); a compare instruction.
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