Operation Operand Description
Table 9-8 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
Error reaction
If the calculated address of the memory location is not between
0 0000H and E FFFFH, the CPU detects a load/transfer error (TRAF)
and calls OB 32. If OB 32 is not loaded, the CPU changes to the stop
mode with the error code TRAF (ISTACK).
9.4.3
Accessing the Global
Memory
Application
This section describes the operations you can use with absolute
memory addresses to access the global memory organized in bytes or
words. The absolute address is the sum of the contents of the BR
register and the constants contained in the operation (-32768 to 32767).
Testing and setting an
"occupied" register in
the global area
You can control access of individual CPUs to commonly used memory
areas by using an "occupied" register. An "occupied" register is assigned
to each commonly used memory area. Each participating CPU must test
this register before accessing the memory area. The "occupied" register
contains either the value ’0’ or the slot ID of the CPU that is presently
using the memory area. When the CPU is finished using the memory
area, it writes ’0’ to the "occupied" register to re-enable the memory
area. (Note the explanations for the operations "set semaphore/SED" and
"enable semaphore/SEE" in Section 3.5.5.)
The TSG operation enables testing and setting of "occupied" registers.
Operation Operand Description
TSG -32768 to
+32767
Add the specified constant to the content
of the BR register and test and set the
location addressed in this way.
Operations with the Base Address Register (BR Register)
CPU 948 Programming Guide
C79000-G8576-C848-04
9 - 25
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