ZiLOG System 8000 User Manual page 50

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the segmented base address is held in a
register pair and the displacement is in
the instruction.
Base Index (BX) addressing mode
Based Indexed addressing is similar to
Based addressing except that the dis-
placement (index), as well as the base,
is held in a register. In nonsegmented
mode, the base address is held in a word
register and the index is held in a word
register. In segmented mode, the seg-
mented base address is held in a regis-
ter pair and the index is held in a word
register.
BCD digit A Binary Coded Decimal digit is encoded
of the ten decimal digits into a 4-bit
code that is simply the first ten binary
numbers in the binary number system
(starting with 0). This code is used to
represent and process numbers in the
base-IO (decimal) format.
break The break is a built-in command used to
exit from loops within the control
structure of the shell. (See shell.)
breakpoint A command that interrupts or stops pro-
gram execution at a specified address in
the program. The address specified in
the breakpoint is the address of the
instruction.
byte A byte is eight contiguous bits; a byte
in memory starts on an addressable byte
boundary.
byte register An 8-bit register. The Z8000 CPU con-
tains
16
general-purpose byte registers,
designated RLn and RHn (n
=
0-7).
code The characters of an originating or
source language, each correlated with
its equivalent expression in an inter-
mediate or target language, for example,
alphanumeric characters correlated with
their equivalent 6-bit expressions in a
binary machine language.
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