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2. CCM
INITIALIZATION
CONSIDERATIONS
CCM MEMORY
INITIALIZATION
OF THE LINE
STATUS WORDS
• The CCM control memory contains 512 wordso This 512-word memory
is divided into 48 sets of line status words and 64 operational word pairs.
(See Section 3.) The line status sets are composed of six line status words,
A through F, while operational words are two-word sets. Each word in
both of these classifications contains 18 bits including parity.
When the LSWs (line status words) and OWs (operational words) have
been established for any COM, they are placed in processor memory and
transferred to the CCM as shown in the following diagram:
In Processor Memory
In CCM Memory
Byte 1
Byte 2
Byte 3
Byte 3
Byte 2
Byte 1
2
5
2°
2
5
2°
24
2°
24 20
2
5
2°
2
5 2°
LSW s must be transferred to the CCM memory in the particular sequence
of their device addresses o OWs will be placed into the specific memory
positions determined by the CCM installation specialists. These locations
are determined after reviewing the OW requirements as specified by the
programmer for each individual CCMo
Standard RCA EDP Procedures
contain the necessary instructions and other pertinent data for determin-
ing and documenting these requirementso
•
Six line status words must be initialized for each active line on the CCM.
However, since parity (17th bit) is generated by hardware, the programmer
need concern himself only with initializing bits ° through 16. Each LSW is
loaded, a byte at a time, as shown below. The least Significant bit in pro-
cessor memory is the least significant bit position in CCM memory.
First Byte in bit positions ° through 5
Second Byte in bit positions 6 through
11
Third Byte in bit positions 12 through 16
For control of remote communication systems, the LSWs are initialized
by the user as follows:
All LSW s are set to ° except:
Bit
A15
co
:hru C7
C13
2-1
Function
Buffer Neutral Status
System Classification
In Data Block
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