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•
Interrupt area
Restart text save area
•
SIE instruction work area
Two internal records for the TEST BLOCK instruction
•
Instruction tracing area
•
Engineering/ scientific assist table
•
Program event recording area
•
Control storage link information
•
K-addressable auxiliary storage area of lK bytes. The contents of this area
varies slightly for System/370-XA and System/370 modes.
Storage Control Function
Each storage control function operates under the control of its associated
instruction processing function to handle all access to processor storage. The
following components are part of each storage control function:
•
High-speed buffer storage and its directory
•
The TLB for translating virtual storage addresses in instructions to real storage
addresses for both System/370 and System/370-XA modes (discussed in
Section 50)
•
The key stack that contains the 7-bit keys for the processor storage installed.
Each key consists of four access control (store protection) bits, one fetch
protection bit, one reference bit, and one change bit.
•
The ECC logic for processor storage - only in the storage control function for
instruction processing function 0 (see Section 60)
Data flow control
•
The input/output
(1/0)
data register that is used to transfer data
(1)
among
the components of the storage control function and (2) between processor
storage and the instruction processing function
The
1/0
data register is 64 bytes wide to improve instruction execution speed.
For fetches/stores involving the instruction processing function (including
those done for the channels), only 8 bytes of the 64-byte 1/0 data register are
used, while 16 bytes are used for fetches/ stores involving processor storage.
70
A Guide
to
the
IBM
4381 Processor
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