Ccu Environment - IBM 3745 Maintenance Information Reference

CCU Environment
The figure below shows all interconnections to the CCU.
Storag
Contra
Osci 11
(TCM a
Power
Suppli
e
1
ator
nly)
es
~
~
To Storage
via SCTl
1
High-
Speed
Buffer
MIOC
I
10C1
I I
IOC2
I
1 1
To Adapters
via IOC Switch
• Storage Control Interconnection (SCTL)
•
~
To MOSS
Writing data to main storage is performed through the write storage data
register (this register is 27 bits wide; 24 data bits
+
3 parity bits). Data
read from storage is written directly into one or more CCU registers and/or
in local storage. Main storage is read and written across the storage data
bus (bidirectional, 36 bits wide) which is the only port to/from main storage
for the whole machine.
• MIOC Interconnection
Through the MIOC interface, the MOSS will be able to obtain/alter the state
of 3745.
• 10 Buses
These are multipurpose compatible buses that are used as the base attach-
ment interface for all channel adapters, 10 Switch, and LAs to the CCU.
• SCTL Oscillator Interconnection
The SCTL 53.1914 MHz quartz oscillator signals are used by the TeM to
generate its timings.
The PUC 80.9824 MHz quartz oscillator signals are used by the PUC and
SCTL2 to generate their timings.
• Power Interface
The power interface provides the CCU with all necessary power voltage
requirements needed
~o
operate all 3745 functions.
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IBM 3745 Maintenance Information Reference (MIR)