NXP Semiconductors MC68HC000EI8

Overview

MC68HC000EI8 from Freescale Semiconductor (formerly Motorola) is a CMOS 16/32-bit microprocessor with 32-bit internal architecture, 24-bit address bus (16 MB addressing), and 16-bit data bus. It operates at up to 8 MHz, supports supervisor/user privilege modes, and features asynchronous bus control with DTACK, BERR, and HALT signals for flexible memory/peripheral interfacing in embedded control systems.

For engineers reviewing the MC68HC000EI8 datasheet, MC68HC000EI8 pinout, MC68HC000EI8 application, or MC68HC000EI8 equivalent, this page delivers verified electrical specs, bus timing constraints, exception handling behavior, and real-world design context for legacy industrial controller upgrades, retro-computing platforms, and deterministic real-time I/O subsystems.

Technical Context

The MC68HC000EI8 implements the full M68000 instruction set with 32-bit registers and 16-bit external data path, enabling efficient 16-bit memory transfers while retaining 32-bit register arithmetic and addressing. Its asynchronous bus interface uses DTACK for variable wait-state insertion and BERR for error signaling - critical for interfacing with slow peripherals or non-standard memory.

Exception processing includes seven vectorable interrupt levels, bus/address error handling with stack frame preservation, and privilege-mode separation between supervisor and user code. The processor executes instructions in pipelined stages but lacks on-chip cache or MMU - requiring external logic for memory management in protected environments.

Key Specifications

Pinout & Package

MC68HC000EI8 is housed in a 64-pin Dual In-Line (DIP) package (Case 740-03, L suffix), with pins arranged in two parallel rows for through-hole mounting on legacy PCBs. Pin functions align with the standard MC68000 family layout, preserving board compatibility across speed grades and process variants.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68000P8 and MC68EC000RC25, the MC68HC000EI8 uniquely balances legacy pin compatibility, industrial temperature operation, and CMOS power efficiency - making it the optimal choice for refurbishment, long-lifecycle spares, and deterministic real-time control where bus transparency matters.

Availability

MC68HC000EI8 is available at Aetrix Electronics and suitable for industrial motion controllers, retro computing platforms, legacy PLC CPU modules, and avionics test equipment requiring stable component supply and long-term obsolescence mitigation.

Supply support for MC68HC000EI8 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, analog, and mixed-signal ICs, with deep roots in Motorola's semiconductor division and a strong heritage in automotive and industrial microcontrollers.

The MC68HC000EI8 belongs to the M68000 family - engineered for deterministic real-time control in industrial automation, telecommunications infrastructure, and early personal computing, emphasizing instruction compatibility, bus flexibility, and ruggedized operation.

FAQ

What is the maximum operating frequency of the MC68HC000EI8?

The MC68HC000EI8 is rated for a maximum clock frequency of 8 MHz under specified voltage and temperature conditions. This speed defines its instruction throughput and determines timing margins for external memory and peripheral interfaces. The MC68HC000EI8 achieves this while maintaining full compatibility with the original M68000 instruction set and bus timing model.

Does the MC68HC000EI8 support both supervisor and user modes?

Yes, the MC68HC000EI8 implements dual privilege modes - supervisor and user - controlled by the S bit in the status register. This hardware-enforced separation allows operating system kernels to protect critical resources while permitting application code to run in restricted contexts. The MC68HC000EI8 handles mode transitions automatically during exception entry and return.

Is the MC68HC000EI8 pin-compatible with the original MC68000P8?

Yes, the MC68HC000EI8 uses the same 64-pin DIP package and identical pinout as the HMOS MC68000P8, including matching signal names, timing relationships, and DC voltage levels. This allows direct replacement in existing designs without PCB modification, though users should verify power supply decoupling due to lower current draw of the CMOS version.

What bus control signals does the MC68HC000EI8 provide for interfacing with slow peripherals?

The MC68HC000EI8 provides DTACK (Data Transfer Acknowledge), BERR (Bus Error), and HALT signals to manage asynchronous bus transactions. DTACK allows external logic to insert wait states; BERR triggers exception handling on invalid accesses; HALT suspends execution for debugging or resource arbitration. These signals are essential for reliable interfacing with EPROMs, FIFOs, or custom ASICs in the MC68HC000EI8 system design.

What is the address space size supported by the MC68HC000EI8?

The MC68HC000EI8 features a 24-bit address bus, supporting a linear 16 MB (2²⁴ bytes) address space. This capacity accommodates large program ROMs, data RAM, and memory-mapped I/O regions typical in industrial controllers and early workstations. Address lines A0–A23 are time-multiplexed with data on D0–D15 in the MC68HC000EI8's bus protocol.