!
116
Flags The
Flags
subsection lists flags that are affected by execution of an instruction.
These flags include the following Auxiliary Area flags.
Abbreviation Name Bit
ER Instruction Execution Error Flag A50003
CY Carry Flag A50004
GR Greater Than Flag A50005
EQ Equals Flag A50006
LE Less Than Flag A50007
N Negative Flag A50008
ER is the flag most commonly used for monitoring an instruction’s execution.
When ER goes ON, it indicates that an error has occurred in attempting to
execute an instruction. The
Flags
subsection of each instruction lists possible
reasons for ER going ON. ER will turn ON if operands are not entered correctly.
Caution Most instructions are not executed when ER is ON. A table of instructions and
the flags they affect is provided in
Appendix B Error and Arithmetic Flag Opera-
tion
.
Indirect Addressing
The DM or EM Area can be used to indirectly address an operand. Indirect DM or
EM addressing is specified by placing an asterisk before the D or E: *D or *E.
(EM Area is available as an option for the CV1000, CV2000, or
CVM1-CPU21-EV2 only.)
The operation of indirect addressing is affected by the PC Setup specified from
the CVSS. The PC Setup can be used to specify whether the content of a word
containing an indirect address contains the BCD data area address or contains
the binary (hexadecimal) PC memory address.
BCD Addressing When indirect DM data is designated as BCD, the address of the desired word
must be in BCD and it must specify the data area address of a word within the
DM or EM Area. The content of the operand word containing the indirect address
(e.g., *D00000) has to be in BCD and has to be between 0000 and 8191 for the
CV500 or CVM1-CPU01-EV2 and between 0000 and 9999 for the CV1000,
CV2000, CVM1-CPU11-EV2, or CVM1-CPU21-EV2. Although CV1000,
CV2000, and CVM1-CPU21-EV2 DM and EM Area addresses go to D24575
and E32765, only the first 10,000 words can be indirectly addressed when indi-
rect DM data is designated as BCD.
When an indirect DM or EM address is specified in BCD, the DM or EM word
specified for the operand will contain the address of the DM or EM word that con-
tains the data that will be used as the operand of the instruction. If, for example,
*D00001 was designated as the first operand of MOV(030), the contents of
D00001 was 2222, and D02222 contained 5555, the value 5555 would be
moved to the word specified for the second operand.
Word Content
D00000 4C59
D00001 2222
D00002 F35A
D02222 5555
D02223 2506
D02224 D541
5555 moved
to A001.
Indicates
D02222.
Indirect
address
(030)
MOV *D00001 A001
Data Areas, Definer Values, and Flags Section 5-3
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