Technical data

Operation Operand Description
Table 9-7 continued:
TRD
Constant
(-32768 to
+32767)
add the specified constant to content
of the BR register and transfer the
content of ACCU 1 to the double word
addressed in this way
1)
ACCU 2
new
= ACCU 1
old
Permissible address area The absolute address must be as follows:
•• for LRW, TRW: between 000H and E3FFH or E800H and
EDFFH
•• for LRD, TRD: between 000H and E3FEH or E800H and
EDFEH
Error reaction If the calculated address of the memory location is not in the
permissible memory area, the CPU detects a runtime error and calls
OB 31, providing it is loaded. If OB 31 is not loaded, the CPU goes to
the stop mode.
In both cases, error IDs are entered in ACCU-1-L, that define the error
in greater detail (see Section 5.6.2).
9.4.3
Accessing the Global
Memory
Application With the following operations, you can access the global memory
organized in bytes or words using an absolute memory address. The
absolute address is the total of the BR register contents and the
constant contained in the operation (-32768 to 32767).
Testing and setting a busy
location in the global area
You can control the access of individual CPUs to common memory
areas using a busy location. Each memory area used by more than one
CPU has a busy location assigned to it that must be tested by each
CPU before it can access this area. The busy location either contains
the value "0" or the slot identifier of the CPU currently using the
memory area. This CPU releases the memory area by
writing "0" to
the busy location again when it is finished.
(Note the explanations
for the operations "set semaphore/SED" and "enable semaphore/SEE"
in Section 3.5.5.).
9
Operations with the Base Address Register (BR Register)
CPU 928B Programming Guide
C79000-B8576-C898-01
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