User`s guide

SET UB

(UB)

Sets the UB handler that supports UNIBUS mapping registers (UMR) hardware in

UNIBUS processors.

Format

SET UB condition

Condition

[NO]INSTAL

INSTAL, the default, allows installation of the UB handler with valid UNIBUS

conﬁgurations.

NOINSTAL prevents installation of the UB handler with valid UNIBUS

conﬁgurations.

PERM=decimal-value

Sets the number of permanent UMRs to reserve for handlers that are not

installed during the boot process.

[NO]SERIAL=octal-value

SERIAL=octal-value forces serial satisfaction of outstanding I/O requests for the

speciﬁed job, where octal-value is the job number. Determine the job number

by issuing the SHOW JOBS command. Serial satisfaction goes into effect at the

next installation of UB (at system boot).

Serialized I/O request satisfaction is often slower than nonserialized satisfaction

for the following reasons:

• UB satisﬁes I/O requests for jobs set to serialized satisfaction at a lower

priority than I/O requests for jobs set to nonserialized satisfaction.

• A request that is queued because of insufﬁcient free UMRs is satisﬁed before

any subsequent request is satisﬁed; I/O requests are always satisﬁed in the

order that they are received. For example, assume UB receives a request

requiring three UMRs and only two UMRs are available. That request is

queued. Assume the next request received requires only two UMRs. The

second request is queued until enough UMRs (three) are free to satisfy the

previous request. With nonserialized satisfaction, the second request would

have been satisﬁed when received.

NOSERIAL=octal-value, the default, satisﬁes outstanding I/O requests for the

speciﬁed job, where octal-value is the job number, as required UMRs are free.

I/O requests are satisﬁed as quickly as possible and not necessarily in serial

order.

RT–11 Command Descriptions 273