Introduction.

Workshop PG5
Instructionlist
Word Instructions:
Word Instructions work with registers, counters, timers, constants, texts, and
db's. Although there are some instructions which depend on the state of the
ACCU, the ACCU isn't that important here. ( see Instruction set booklet ).
Not all the instructions allow you to use all the possible elements ( register
counter ect) as parameters. Please refer to the booklet or the online help.
A lot of the instructions not only write a result to the element ( register, counter
ect), but they also note some general information about the result into four
special flags called arithmetic flags. The flags are:
1. Zero flag ( Example: Z flag is set if the copy instruction copies an empty
register )
2. Error flag (Example: The Error (E) flag is set if the definition text of a
SASI instruction is missing or invalid). SASI=SAIA Assigned Serial Interface.
3. Negative flag ( Example: is set if the result of a calculation was negative )
4. Positive flag ( always inverse to the negative flag )
Example:
ADD R 1
R 33
R 46
The values of register R 1 and register R 33 are
added. The result is in register R 46.
The flags N,P , Z are set according to the value in
register R 46
ACCU
Register
Constant
Timer
Counter
Register
Constant
Timer
Counter
?
COPY
ADD…
..
Word
Instructions:
ALU
32Bit
?
JR
ACC…
Register
Constant
Timer
Counter
E Z N P
Error
Arithmetic Flags
Other Instructions (mainly the Control instruction family) are only executed, if
the mentioned Arithmetic flag is set to high.
Example: JR Z Label ;The Jump is only done, if the Zero flag is
high.
Most Word-Instructions are executed unconditionally.
Zero
Negative
Positive
PG5-07-E © Saia-Burgess Controls Ltd. Page 7-11