Table of Contents

I/O Complete (IOC)/OP=98

Format

OP AF BF A Syllable

OP = 98

AF Unused and reserved. Can be specified as an indirect field length. A literal flag causes an invalid instruction fault (IEX=21).
BF Variant, which can be specified as an indirect field length. The following variant can be specified:

The use of other BF values causes an Invalid Instruction fault (IEX=26).

The A Syllable is the address of the 6-digit MAST number and may be indexed, indirect, or extended. The final address controller must specify UN or cause an Invalid Instruction fault (IEX=03).

Note This instruction can only be executed with the Privileged Enable toggle set, or an Invalid Instruction fault (IEX=02) occurs.

Function

IOC examines the specified MAST entry and may update certain fields based on the BF variant.

IOC is a companion instruction to the CIO instruction.

Variants

The variants are described as follows:

BF=00 (Decrement I/O in process count)

IOC decrements the I/Os in process field and reports the status, through the COMS, of the new I/Os in the in process field and the inhibited I/O memory area flag. If the CIO instruction which specifies a MAST entry is used prior to initiating an I/O request, this variant should be used after the I/O request completion has been harvested by the PIQ instruction.

The MAST number must be decimal and the value of 40 times the MAST number must be smaller than 1 million digits; otherwise, an invalid instruction fault (IEX=07) is reported.

IOC uses the MAST number as an array subscript into the MAST to locate the specified entry.

IOC obtains exclusive access rights to the specified MAST entry, and performs the following:

BF=01 (Set I/O Inhibited Memory Area)

IOC reports, through the COMS, the status of the I/Os in the process field and sets the inhibited I/O memory area flag.

The MAST number must be decimal and the value of 40 times the MAST number must be smaller than 1 million digits; otherwise, an invalid instruction fault (IEX=07) is reported.

IOC uses the MAST number as an array subscript into the MAST to locate the specified entry.

IOC obtains exclusive access rights to the specified MAST entry.

IOC sets the I/O inhibited memory area flag and checks the number of I/Os in process field of the entry.

Comparison Flags

BF=00

BF=01

Overflow Flag

The overflow flag is not changed by this instruction.