RCA 70/46 Reference Manual page 52

Channel Command
Word (CCW)
(Cont'd)
Input/Output Operation
mand word designates an area of main memory at which to continue
the current operation. When one channel command word has a lapsed
byte count, the next channel command word in sequence is auto-
matically fetched. The current operation is continued at the main
memory area specified by the new channel command word. The
command code of the new CCW is ignored unless it specifies a
Transfer in Channel. If any of the following channel status byte
conditions occur, the chain is terminated (see Channel Status Byte
for further definition) :
Program Check
Protection Check
Channel Control Check
Channel Data Check (if the operation is a write)
Incorrect Length Condition
When data chaining, the chain data flag in the last channel command
word must be reset. This causes the data chain to be terminated
upon completion of the operation specified by this CCW.
2. Bit position 33 is the Chain Command flag (CC). The 70/46 Proces-
sor can perform several operations to an input/output device by
executing one Start Device instruction. When command chaining is
specified by setting this bit, a chain (series of channel command
words in sequence) is used and each channel command word specifies
the operation to be performed. When the operation specified by one
channel command word is completed, the next channel command
word in sequence is automatically fetched and the operation specified
is initiated. If any of the following conditions occur, the chain is
terminated:
a. Channel status byte conditions (see channel status byte for
further definition).
Incorrect Length Condition and suppress length flag is zero.
Program Check
Protection Check
Channel Control Check
b. Standard device byte conditions (see standard device byte for
further definition).
Secondary Indicator is set
Device Inoperable is set
Device End is not set
When command chaining, the chain command flag in the last channel
command word must be reset. This causes the command chain to be
terminated upon completion of the operation specified by this CCW.
3. Bit position 34 is the Suppress Length Indication flag (SLI). Incor-
rect length occurs in the 70/46 Processor when the number of
bytes specified in the channel command word is not equal to the
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