Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

5.3.1.1.2Table Lookup and Interpolation (TBL). To maximize throughput for real-time applications, reference data is often precalculated and stored in memory for quick access. The storage of sufficient data points can require an inordinate amount of memory. The TBL instruction uses linear interpolation to recover intermediate values from a sample of data points, and thus conserves memory.

When the TBL instruction is executed, the CPU32 looks up two table entries bounding the desired result and performs a linear interpolation between them. Byte, word, and long- word operand sizes are supported. The result can be rounded according to a round-to- nearest algorithm or returned unrounded along with the fractional portion of the calculated result (byte and word results only). This extra precision can be used to reduce cumulative error in complex calculations. See 5.3.4 Using the TBL Instructions for examples.

5.3.1.2UNIMPLEMENTED INSTRUCTIONS. The ability to trap on unimplemented instructions allows user-supplied code to emulate unimplemented capabilities or to define special-purpose functions. However, Motorola reserves the right to use all currently unimplemented instruction operation codes for future M68000 enhancements. See 5.5.2.8 Illegal or Unimplemented Instructions for more details.

5.3.2Instruction Format and Notation

All instructions consist of at least one word. Some instructions can have as many as seven words, as shown in Figure 5-6. The first word of the instruction, called the operation word, specifies instruction length and the operation to be performed. The remaining words, called extension words, further specify the instruction and operands. These words may be immediate operands, extensions to the effective address mode specified in the operation word, branch displacements, bit number, special register specifications, trap operands, or argument counts.

15

0

OPERATION WORD

(ONE WORD, SPECIFIES OPERATION AND MODES)

SPECIAL OPERAND SPECIFIERS

(IF ANY, ONE OR TWO WORDS)

IMMEDIATE OPERAND OR SOURCE ADDRESS

EXTENSION

(IF ANY, ONE TO THREE WORDS)

DESTINATION EFFECTIVE ADDRESS EXTENSION

(IF ANY, ONE TO THREE WORDS)

Figure 5-6. Instruction Word General Format

5- 12MC68340 USER’S MANUALMOTOROLA

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Motorola MC68340 manual Instruction Format and Notation, Instruction Word General Format
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MC68340 specifications

The Motorola MC68340 is a highly integrated microprocessor that was introduced in the early 1990s. It belongs to the 68000 family of microprocessors and is designed to cater to the demands of embedded systems, particularly in telecommunications and networking applications. This chip represents a significant evolution in microprocessor technology by combining a microprocessor core with additional peripherals on a single chip, making it an attractive solution for engineers looking to design compact and efficient systems.

One of the key features of the MC68340 is its 32-bit architecture, which allows for significant processing power and data handling capabilities. This architecture enables the processor to handle larger data sizes and perform more complex calculations compared to its 16-bit predecessors. The MC68340 operates at clock speeds typically ranging from 16 MHz to 25 MHz. Its dual instruction pipeline enhances throughput, allowing for simultaneous instruction fetches and executions, which significantly boosts performance.

A notable characteristic of the MC68340 is the inclusion of integrated peripherals, which help reduce the overall component count in a system. Key integrated components include a memory management unit (MMU), a direct memory access (DMA) controller, and various communication interfaces such as serial ports. The memory management capabilities enhance the processor's ability to manage memory resources efficiently, enabling it to support multitasking environments commonly found in modern computing.

In terms of connectivity, the MC68340 features connections for both synchronous and asynchronous serial communication, making it well-suited for networking tasks. The processor supports a range of bus standards, including address and data buses, which facilitate seamless interaction with peripheral devices.

Another important aspect of the MC68340 is its flexibility. The processor supports multiple operating modes, including multiple CPU configurations and compatibility with the Motorola 68000 family, allowing for easier integration into existing systems.

Moreover, the MC68340 boasts low power consumption compared to many of its contemporaries, making it an excellent choice for battery-operated applications, enhancing its appeal in sectors like telecommunications, industrial control, and automotive systems. Its combination of performance, integration, versatility, and efficiency has secured the MC68340 a reputable position in the annals of embedded systems technology, proving to be a valuable asset for developers and engineers alike.
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