Introduction.

Workshop PG5
Instructionlist
Index Register:
Each and every COB has an internal register which is called an index register.
The content of this register can be manipulated by five instructions:
SEI
SEt Index register
INI
INcrement Index register
DEI
DEcrement Index register
STI
STore Index register
RSI
ReStore Index register
Most of the instructions can work with the content of this register and perform
indirect commands with it. (these instructions are indicated in the booklet). If
you add an X to the command name ( Example LD =>LDX ) you tell the PCD
that you are using the index register in this program line.
Example:
COPY
Normally an instruction like COPY would work like this:
COPY R 10
R 40
The content of R 10 is COPIED into R 40
COPYX
COPYX works different:
SEI K 2
COPYX R 10
R 40
The Index register is set to 2
R 10 is not copied into R 40, but the content of
register R 12 is copied into R 42 ( add the content
of the index register to R 10 and R 40).
So now that you know the basics, we can start to write our first program.
PG5-07-E © Saia-Burgess Controls Ltd. Page 7-14