Technical data

•• If the OB cannot read from the page,
-
all ACCUs: remain unchanged,
-
RLO: = 0,
-
all other bit and word
condition codes:
are cleared.
Possible errors
•• wrong length ID in ACCU-3-LH
•• source address on the page is wrong or does not exist
•• specified page number does not exist
6.21.3
OB 218: Reserving
a Page
The special function organization block transfers the number of the
CPU to a particular page, providing the contents of the memory
location addressed on this page are
zero. As long as the CPU number
is entered in this location, the page is reserved for this CPU and
cannot be used by other CPUs.
Organization block OB 218 is used to synchronize data transfer and is
particularly important when
large blocks of data must be transmitted
as one unit. In the multiprocessor mode, no more than 4 bytes are
transferred per bus allocation. Reserving a page is therefore
advantageous.
Addressing the page, reading and, if applicable, writing the slot
identifier is one
program unit that must not be interrupted.
Parameters Accus
a) ACCU-2-LL
Number of the page to be reserved,
permitted values: 0 to 255
b)
ACCU-1-L
Destination address on the page,
permitted values: 0 to 2047
(The contents of ACCU 3 and 4 are irrelevant.)
OB 216 to OB 218: Page Access
CPU 928B Programming Guide
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