Motorola CPU32 Bedienungsanleitung Seite 513

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Supervisor (Privileged) Instructions
MOTOROLA M68000 FAMILY PROGRAMMER’S REFERENCE MANUAL 6-59
PSAVE PMMU Save Function PSAVE
(MC68851)
Operation: If Supervisor State
Then MC68851 Internal State, Programmer
Registers State Frame
Else TRAP
Assembler
Syntax: PSAVE < ea >
Attributes: Unsized, Privileged
Description: The MC68851 suspends execution of any operation that it is performing and
saves its internal state and some programmer registers in a state frame located at the
effective address. The following registers are copied: PMMU status, control root
pointer, supervisor root pointer, current access level, valid access level, and stack
change control. If any breakpoint is enabled, all breakpoint acknowledge control and
breakpoint acknowledge data registers are copied. After the save operation, the
MC68851 is in an idle state waiting for another operation to be requested. Programmer
registers are not changed.
The state frame format saved by the MC68851 depends on its state at the time of the
PSAVE operation. In the current implementation, three state frames are possible:
IDLE: This state frame is 36 ($24) bytes long. A PSAVE of this size state frame indi-
cates that the MC68851 was in an idle state with no coprocessor operations
in progress and no breakpoints enabled. A module call operation may or may
not have been in progress when this state frame was saved.
MID-COPROCESSOR:This state frame is 44 ($2C) bytes long. A PSAVE of this size
frame indicates that the MC68851 was in a state with a coprocessor or mod-
ule call operation in progress and no breakpoints enabled.
BREAKPOINTS ENABLED:This state frame is 76 ($4C) bytes long. A PSAVE of this
size state frame indicates that one or more breakpoints were enabled. A
coprocessor or module call operation may or may not have been in progress.
PMMU Status Register: Not affected
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