Function
Call
(FC)
General
Description
Format
(51)
Condition Code
Interrupt
Action
Notes
Privileged
Instructions
• This
instruction
is used to execute
Elementary
Operation
(EO)
routines
contained
in
Read Only Memory
(ROM).
The I field is used
to
specify
one
of
128 possible EO routines.
The
address
field specifies
the
address
of
the
parameters
used by
the
specified EO routine.
9A
o
7 8
15 16 19 20
31
• Unchanged by
this
instruction, however,
the
routine
called
may
modify
the
condition codes.
• Op Code
Trap.
Power
Failure.
Machine
Check.
Privileged Operation.
Addressing.
Paging
Error.
Paging
Queue.
Others
as
defined by
the
specifications
of
the
routine
called.
• 1. The I field specifies one
of
128 possible EO routines, called Special
Functions. All 8-bit codes in which
the
24
bit
is zero
are
available
for
Special Functions. This
instruction
is only
incorporated
on
the
70/46 Processor. The routine specified by
the
I field
must
be incorpo-
rated
in
the
ROM. Otherwise,
an
Op Code
Trap
Interrupt
condi-
tion occurs.
2.
This
instruction
is available to 70/46
programs
only.
If
it
is executed
in the
70/45 mode,
an
Op Code
Trap
Interrupt
condition occurs.
3.
If
a location outside
the
available memory is addressed,
an
Address-
ing
Interrupt
condition occurs.
4.
If
this
instruction
is
attempted
under
any
of
the
following conditions,
a
Paging
Error
Interrupt
condition occurs
and
the
instruction
is
terminated
with
unpredictable
results:
a. A nonexistent
Translation
Table element is
addressed
(i.e.,
the
two unused bits
of
a segment field of a
virtual
address
are
not
zero) .
b.
A 2,048-byte page is addressed
in
the
high-order
address
half
of
a 4,096-byte page.
c.
A
write
operation into a location
within
a non-writable page is
attempted.
90
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