Processor Storage - IBM 4381 Manual

Processor Storage
Processor storage is available for 4381 Processor uniprocessor model groups as
follows:
Processor Storage Sizes Storage
4381 Model Group
in Megabytes (Mb)
Model
11
4 Lil
8 Mll
16 Pll
12
8
M12
16 P12
24 Q12
32 R12
13
8 M13
16 P13
24
Q13
32 Rl3
1
4 LI
8 Ml
16
Pl
2 4 L2
8 M2
16
P2
24
Q2
32 R2
Field upgrades from one processor storage model to another in the same 4381
model group are supported for all uniprocessor model groups. A portion of the
installed processor storage is reserved for processor use and is called auxiliary
storage.
Access to processor storage is made via the storage control function, which
operates under the control of the instruction processing function. The path to and
from processor storage is 16 bytes wide (two doublewords). Data that
enters/leaves processor storage is aligned on a doubleword boundary.
Error checking and correction (ECC) hardware provides automatic detection and
correction of all single-bit processor storage errors and detection of all double-bit
and many multiple-bit errors. Certain double-bit errors can also be corrected by
microcode. ECC logic is contained in the storage control function and performs
checking on a doubleword basis. The ECC feature and double-bit error correction
are discussed in Section 60.
Store and fetch protection are standard. For 4381 uniprocessor configurations
with up to 16Mb of processor storage, one 7-bit storage protection key is provided
Section 20: 4381 Processor Uniprocessor Model Groups
35