## ALP Programming Guide and Reference

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### Description

The save instructions write the current FPU state (environment and register stack) to the specified destination, and then re-initialize the FPU. The environment consists of the FPU control word, status word, tag word, and error pointers (both data and instruction).

The state layout in memory depends on both operand size and the current operating mode of the processor. The USE attribute of the current code segment determines the operand size: the 94-byte operand applies to USE16 segment, and the 108-byte operand applies to a USE32 segment. Refer to the Intel documentation for the environment layouts for both operand sizes in both real mode and protected mode. (In virtual-8086 mode, the real mode layout is used.) The stack registers, beginning with ST and ending with ST( 7), are stored in the 80 bytes that immediately follow the environment image.