Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

All unimplemented instructions are reserved for use by Motorola for enhancements and extensions to the basic M68000 architecture. Opcode pattern $4AFC is defined to be illegal on all M68000 family members. Those customers requiring the use of an unimplemented opcode for synthesis of "custom instructions," operating system calls, etc., should use this opcode.

Exception processing for illegal and unimplemented instructions is similar to that for traps. The instruction is fetched and decoding is attempted. When the processor determines that execution of an illegal instruction is being attempted, exception processing begins. No registers are altered.

Exception processing follows the regular sequence. The vector number is generated to refer to the illegal instruction vector or in the case of an unimplemented instruction, to the corresponding emulation vector. The illegal instruction vector number, current PC, and a copy of the SR are saved on the supervisor stack, with the saved value of the PC being the address of the illegal or unimplemented instruction.

5.5.2.9PRIVILEGE VIOLATIONS. To provide system security, certain instructions can be executed only at the supervisor access level. An attempt to execute one of these instructions at the user level will cause an exception. The privileged exceptions are as follows:

•AND Immediate to SR

•EOR Immediate to SR

•LPSTOP

•MOVE from SR

•MOVE to SR

•MOVE USP

•MOVEC

•MOVES

•OR Immediate to SR

•RESET

•RTE

•STOP

Exception processing for privilege violations is nearly identical to that for illegal instructions. The instruction is fetched and decoded. If the processor determines that a privilege violation has occurred, exception processing begins before instruction execution.

Exception processing follows the regular sequence. The vector number (8) is generated to reference the privilege violation vector. Privilege violation vector offset, current PC, and SR are saved on the supervisor stack. The saved PC value is the address of the first word of the instruction causing the privilege violation.

5- 48MC68340 USER’S MANUALMOTOROLA

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Motorola MC68340 manual Lpstop, Move USP Movec Moves, Reset RTE Stop
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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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