Control Data Cyber 170 State Hardware Reference Manual page 181

Programming Information
This chapter contains special programming information about the CP, CM, PPs,
system console, real-time clock, two-port multiplexer, and maintenance channel.
CP Programming
CYBER 170 Exchange Jump
The CP operates in either CYBER 170 job mode, which is interruptable, or CYBER
170 monitor mode, which is not interruptable.
A hardware flag called the CYBER
170 monitor flag (MF) indicates the mode in which the CP is executing a job.
The CP uses a CYBER 170 exchange jump operation to switch from CYBER 170 job
mode to CYBER 170 monitor mode and back again.
The
execution of a CYBER 170
exchange jump permits the
CP
to send pertinent information from the operating
and control registers to CM and permits CM to send new information to the same
registers. The information that flows from and into the operating and control
registers during a CYBER 170 exchange jump is called a CYBER 170 exchange
package (figure 5 - 1 ) .
The CP 013 instruction and the PP 2600, 2610, and 2620 instructions initiate a
CYBER 170 exchange jump operation. A CYBER 170 exchange jump instruction
starts or interrupts the CP and provides CM with the first address of a 16-word
exchange package. For the 013 instruction with MF set (CP in monitor mode),
the starting address of the CYBER 170 exchange package is Bj plus K. With MF
clear (CP in job mode), the address is the monitor address (MA).
For the 2600
instruction, the CYBER 170 exchange package address is
A
plus R when bit 17 of
the A
register is set. When this bit is clear, the address is A.
For the 2610
instruction with MF set, the instruction is a pass. With MI? clear, the CYBER
170 exchange package address is A plus R when bit 17 of the A
register is set.
When this bit is clear, the address is A. For the 2620 instruction with MF
set, the instruction is a pass. With
MF
clear, the CYBER 170 exchange package
address is MA of the outgoing CYBER 170 exchange package.