NXP Semiconductors MC68HC000RC16

Overview

MC68HC000RC16 from Freescale Semiconductor (formerly Motorola) is a CMOS 16-bit microprocessor core compatible with the M68000 architecture, featuring a 16-bit external data bus, 24-bit address bus supporting up to 16 MB memory space, and 16 MHz maximum clock frequency. It operates in both user and supervisor modes, implements full exception handling including bus error and reset vectors, and targets embedded control systems requiring deterministic real-time interrupt response.

For engineers reviewing the MC68HC000RC16 datasheet, MC68HC000RC16 pinout, MC68HC000RC16 application, or MC68HC000RC16 equivalent, key selection criteria include its 16-bit bus width, 16 MHz operation, CMOS power efficiency, asynchronous bus interface timing, and compatibility with legacy M68000 software and peripheral ecosystems.

Technical Context

The MC68HC000RC16 implements the full M68000 instruction set architecture with 32-bit internal registers and ALU, but presents only 16 data lines externally and uses a 24-bit address bus for memory mapping. Its bus interface supports fully asynchronous, pseudo-asynchronous, and synchronous read/write cycles, with DTACK, BERR, and HALT signals enabling flexible system timing coordination.

Exception processing includes seven priority levels with vector-based dispatch, stack frame preservation on entry, and dedicated supervisor/user privilege modes enforced via status register bits. The processor supports 3-wire and 2-wire bus arbitration protocols and executes instructions with cycle-accurate timing defined per operation type (e.g., MOVE, JMP, arithmetic).

Key Specifications

Pinout & Package

MC68HC000RC16 is housed in a 68-lead Quad Flat Pack (QFP) package per Case 765A-05 (RC suffix), measuring 24.0 mm × 24.0 mm with 0.65 mm lead pitch and surface-mount configuration.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-bit microprocessor applications.

Compared with MC68HC000RC16, MC68EC000FN16 offers higher pin count and simplified bus signaling but sacrifices VMA-based address decoding flexibility, while HD64180 trades M68000 compatibility for integrated peripherals and lower clock speed-making MC68HC000RC16 optimal for legacy software continuity and deterministic timing in industrial control.

Availability

MC68HC000RC16 is available at Aetrix Electronics and suitable for industrial PLC controllers, legacy CNC retrofit systems, and medical diagnostic UI modules requiring stable component supply and long-term obsolescence mitigation.

Supply support for MC68HC000RC16 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Freescale Semiconductor (now part of NXP Semiconductors) was a leading designer of embedded processors, known for automotive, industrial, and networking silicon before its 2015 acquisition.

The MC68HC000 product line extended the M68000 architecture into low-power CMOS for industrial control and instrumentation, emphasizing software compatibility, deterministic timing, and robust bus interfacing over raw performance.

FAQ

What is the maximum operating frequency of the MC68HC000RC16?

The MC68HC000RC16 is rated for a maximum clock frequency of 16 MHz under specified voltage and temperature conditions. This frequency determines instruction execution speed and bus cycle timing margins. All AC electrical specifications-including read/write setup/hold times and DTACK assertion windows-are validated at this rate. Operation above 16 MHz is not guaranteed and may result in timing violations or undefined behavior.

Does the MC68HC000RC16 support 32-bit instructions and addressing?

The MC68HC000RC16 executes the full 32-bit M68000 instruction set and maintains 32-bit internal registers, but its external interface is limited to a 16-bit data bus and 24-bit address bus. It does not support true 32-bit external data transfers or 32-bit physical addressing beyond 16 MB. Software written for 32-bit M68000 variants will run correctly, but memory-mapped I/O and external memory access are constrained by the 24-bit address space.

How does the MC68HC000RC16 handle bus errors and exceptions?

The MC68HC000RC16 uses a dedicated BERR input to detect invalid memory or I/O accesses, triggering exception vector 2 and pushing a 6-word stack frame containing PC, SR, and other context. It supports 256-byte vector table addressing starting at $000000, with priority-encoded interrupts and synchronous reset behavior. The status register's supervisor/user mode bit enforces privilege separation during exception handling.

What package type is used for the MC68HC000RC16?

The MC68HC000RC16 is packaged in a 68-lead Quad Flat Pack (QFP) conforming to Case 765A-05, identified by the "RC" suffix. Its dimensions are 24.0 mm × 24.0 mm with 0.65 mm lead pitch and gull-wing surface-mount leads. This package supports high-density PCB layouts while providing adequate thermal dissipation for industrial ambient temperatures up to +70°C.

Is the MC68HC000RC16 pin-compatible with the original MC68000?

No, the MC68HC000RC16 is not pin-compatible with the original HMOS MC68000 due to differences in pin assignment, power pin locations, and omission of certain signals (e.g., FC0–FC2 function codes are redefined). While electrically and functionally compatible at the architectural level, PCB layout must be redesigned to accommodate the 68-lead QFP footprint and updated signal routing-particularly for DTACK, BERR, HALT, and VMA connections.