RCA Spectra 70 - Page 84

From "Servicing a Data Transfer"
Byte Count :: ~ and Data Chaining
is specified
13~ ________ ~ ________ ~
Yes
Test Standard Device
Byte for Status
Modifier Condition?
No
11r---------~--------~
12
13
Fetch the Next CCW and
Place it in the Appropriate
Channel Registers in
Scratch Pad Memory
No
Input/Output Operation
Yes
10
Increment the Next CCW
Address by 8
(See Note 1, 2)
Yes
Is Main Memory Address
in Transfer in Channel
Command on a Double-Word
Boundary?
17
No
Yes
16
Transfer Main Memory
Address in Transfer in
Channel Command in Next
CCW Address
Send Command to
Specified Devic.e
1- ____________ ... No (Data Chain)
Set Program Check Bit
in Channel Status Byte
14 __ ------~---- __
Is this a
Burst Mode Operation?
14
No
Stare Subchonnel Registers
back in Non-Addressable
Main Memory
Yes
Yes
(See Note 4)
Is this a Multiplexor
Channel Operation?
No
Continue Processing
Is this a Data
Chai n Operation
Yes
Tell Device to Set an
End Condition
Figure 10. Functional Logic of End and Chaining Servicing (Cont'd)
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