8087 Numeric Data Processor (NDP)

The 8087 Numeric Data Processor (NDP) is a coprocessor designed to perform floating-point arithmetic operations on the Intel 8086 and 8088 processors. It extends the capabilities of the base processor by offloading complex mathematical calculations to a dedicated unit.

Stack Register in 8087

The 8087 NDP has a dedicated stack register that is used for temporary storage of intermediate results during floating-point calculations. This stack is separate from the main memory stack used by the CPU.

Number of Stack Registers

The 8087 NDP has a total of 8 stack registers available for use. These registers are organized as a last-in-first-out (LIFO) stack and are used for storing operands, intermediate results, and control information during floating-point operations.

Stack Register Organization

The 8087 stack registers are identified as ST(0) through ST(7), where ST(0) is the top of the stack and ST(7) is the bottom. The stack registers are 80 bits wide and can store floating-point values with precision up to 64 bits.

Usage of Stack Registers

The stack registers are used for various purposes during floating-point calculations, including:

1. Storing operands: Before performing an arithmetic operation, the operands are loaded onto the stack registers. The top of the stack (ST(0)) holds the first operand, and the second operand is placed on the next stack register (ST(1)).

2. Performing calculations: The 8087 NDP performs arithmetic operations using the values stored in the stack registers. The results are stored back onto the stack, allowing for chaining multiple calculations together.

3. Temporary storage: The stack registers are used for temporary storage of intermediate results during complex calculations. This allows for efficient handling of complex mathematical expressions.

Conclusion

In conclusion, the 8087 NDP has a total of 8 stack registers available for use. These registers provide temporary storage for operands, intermediate results, and control information during floating-point calculations. The stack registers are organized as a LIFO stack and are an integral part of the 8087 coprocessor's architecture.