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Intel 80C196NU Accumulator Control and Status Register Accstat, Bit Function Number Mnemonic

Models: Microcontroller 80C196NU 8XC196NP

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ADVANCED MATH FEATURES

3.4ACCUMULATOR CONTROL AND STATUS REGISTER (ACC_STAT)

The ACC_STAT register controls the operating mode and reflects the status of the accumulator. The mode bits (FME and SME) are effective only for signed multiplication. Table 3-2 describes the 80C196NU’s operation with each of the four possible configurations of these bits.

ACC_STAT

Address:

0BH

(80C196NU)

Reset State:

00H

The accumulator control and status (ACC_STAT) register enables and disables fractional and saturation modes and contains three status flags that indicate the status of the accumulator’s contents.

80C196NU

7

FME

SME

—

—

 

 

 

 

0

—

STOVF

OVF

STSAT

 

 

 

 

Bit

Bit

Function

Number

Mnemonic

 

 

 

 

7

FME

Fractional Mode Enable

 

 

Set this bit to enable fractional mode. (See Table 3-2.) In this mode, the

 

 

result of a signed multiplication instruction is shifted left by one bit before it

 

 

is added to the contents of the accumulator.

 

 

For unsigned multiplication, this bit is ignored.

 

 

 

6

SME

Saturation Mode Enable

 

 

Set this bit to enable saturation mode. (See Table 3-2.) In this mode, the

 

 

result of a signed multiplication operation is not allowed to overflow or

 

 

underflow.

 

 

For unsigned multiplication, this bit is ignored.

 

 

 

5:3

—

Reserved; for compatibility with future devices, write zeros to these bits.

 

 

 

2

STOVF

Sticky Overflow Flag

 

 

For unsigned multiplication, this bit is set if a carry out of bit 31 occurs.

 

 

Unless saturation mode is enabled, this bit is set for signed multiplication to

 

 

indicate that the sign bit of the accumulator and the sign bit of the addend

 

 

are equal, but the sign bit of the result is the opposite. (See Table 3-2.)

 

 

Software can clear this flag; hardware does not clear it.

 

 

 

1

OVF

Overflow Flag

 

 

This bit indicates that an overflow occurred during the preceding accumu-

 

 

lation. (See Table 3-2.)

 

 

This flag is dynamic; it can change after each accumulation.

 

 

 

0

STSAT

Sticky Saturation Flag

 

 

This bit indicates that a saturation has occurred during accumulation with

 

 

saturation mode enabled. (See Table 3-2.)

 

 

Software can clear this flag; hardware does not clear it.

 

 

 

Figure 3-2. Accumulator Control and Status (ACC_STAT) Register

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Intel 80C196NU, 8XC196NP, Microcontroller Accumulator Control and Status Register Accstat, Bit Function Number Mnemonic
Page 53 Page 55

Microcontroller, 80C196NU, 8XC196NP specifications

The Intel 8XC196NP and 80C196NU microcontrollers are part of Intel's renowned 16-bit microcontroller series that gained popularity in the 1980s and 1990s for embedded systems applications. Designed for a variety of applications, these microcontrollers are characterized by their robust performance, versatility, and industry-standard architecture.

The 8XC196NP features an enhanced instruction set with over 100 instructions, allowing for efficient code execution. It operates at clock speeds up to 16 MHz, which contributes to improved performance in time-sensitive applications. The microcontroller is equipped with a 16-bit data bus, enabling more efficient data handling compared to its 8-bit predecessors, thus accommodating complex algorithms and large data sets.

In terms of memory architecture, the 8XC196NP supports an addressable memory space of up to 64 KB of program memory and 64 KB of data memory. This configuration provides sufficient space for large applications while ensuring fast data access. The microcontroller includes integrated features such as timers, serial I/O capabilities, and interrupt processing, which enhance its functionality for real-time applications and control mechanisms.

The 80C196NU, on the other hand, is designed for lower power operation, making it suitable for battery-powered devices. This microcontroller maintains similar features to the 8XC196NP while offering advancements that support low-power consumption. The 80C196NU can also function in a range of temperature environments, making it adaptable for industrial applications.

Both the 8XC196NP and 80C196NU support external memory interfacing, allowing designers to expand the system's capability by connecting additional ROM and RAM. This flexibility makes them appealing for developing complex systems, such as motor controls, industrial automation, and consumer electronics.

Another standout feature of these microcontrollers is their built-in debugging capabilities. Intel provided hardware and software tools that enabled developers to test and troubleshoot their applications effectively, reducing the development time and increasing reliability.

Overall, the Intel 8XC196NP and 80C196NU microcontrollers stand out for their dependability, versatility, and performance, contributing significantly to the evolution of embedded system design. Their legacy continues to influence modern microcontroller technology, ensuring their relevance in a wide array of applications today.