NXP Semiconductors MC68020EH16E

Overview

MC68020EH16E from Motorola (later Freescale) is a 32-bit, second-generation enhanced microprocessor with on-chip 256-byte instruction cache, 32-bit data and address buses (A31–A0), and full 32-bit internal architecture. It operates at 16 MHz, supports supervisor/user privilege levels, coprocessor interface (CP0–CP3), and asynchronous bus timing for memory and I/O expansion in embedded control systems.

For engineers reviewing the MC68020EH16E datasheet, MC68020EH16E pinout, MC68020EH16E application, or MC68020EH16E equivalent, key selection considerations include clock frequency tolerance, bus arbitration support, cache enable/disable control, exception vector mapping, and compatibility with MC68881 FPU and MC68851 MMU coprocessors.

Technical Context

The MC68020EH16E implements a five-stage pipeline (fetch, decode, execute, address, writeback) with dynamic bus sizing and misaligned operand handling. It features a Harvard-style on-chip instruction cache (256 bytes, direct-mapped), no data cache, and supports both big-endian byte ordering and 32-bit linear addressing with optional MMU interfacing.

Its bus interface uses asynchronous handshake signals (AS, DS, DTACK, BR, BG, BGACK), transfer size encoding (SIZ1/SIZ0), and function code lines (FC2–FC0) to distinguish instruction fetch, data access, and space cycles. Exception processing includes 256-vector table support, stack frame formats for bus/address errors, and trace/debug primitives via emulator support signals.

Key Specifications

Pinout & Package

MC68020EH16E is housed in a 132-pin ceramic PGA (Pin Grid Array) package, designated RC suffix per Motorola ordering nomenclature. Thermal and mechanical data confirm 1.27 mm pin pitch and 39.62 mm × 39.62 mm body dimensions.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 32-bit embedded microprocessor applications.

Compared with MC68020EH16E, MC68020RC16 offers identical performance and compatibility, whereas MC68EC020RC16 sacrifices address space and coprocessor flexibility for lower cost and power - making it unsuitable as a drop-in replacement in full-featured systems.

Availability

MC68020EH16E is available at Aetrix Electronics and suitable for industrial motion control, legacy workstation repair, avionics data acquisition, and communications protocol stack development requiring stable component supply across long-lifecycle programs.

Supply support for MC68020EH16E 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

Motorola Semiconductor (later Freescale Semiconductor) was a pioneering U.S. semiconductor manufacturer known for the 68000 family and automotive, industrial, and communications ICs.

The MC68020EH16E belongs to the M68000 family's second-generation microprocessors, designed for high-performance embedded computing and early UNIX workstations requiring full 32-bit addressing and coprocessor extensibility.

FAQ

What is the maximum operating frequency of the MC68020EH16E?

The MC68020EH16E is rated for a maximum clock frequency of 16 MHz, as indicated by the "16" in its part number suffix. This speed grade is validated across commercial temperature range (0°C to +70°C) and defines the upper limit for reliable instruction execution, bus timing, and cache operation. Exceeding 16 MHz may cause timing violations in AS/DS/DTACK sequences or pipeline stalls.

Does the MC68020EH16E include an on-chip data cache?

No, the MC68020EH16E includes only a 256-byte on-chip instruction cache; it has no data cache. The instruction cache is direct-mapped and must be explicitly managed by software (e.g., cache invalidation after self-modifying code). Data accesses always go off-chip via the 32-bit data bus, requiring external memory design to meet timing constraints.

Which coprocessors are compatible with the MC68020EH16E?

The MC68020EH16E supports the MC68881 floating-point unit and MC68851 memory management unit via its dedicated four-line coprocessor interface (CP0–CP3) and protocol-defined primitives. These devices connect directly to the CPU bus and rely on the MC68020EH16E's exception vectoring and context save/restore instructions for seamless integration.

What package type is used for the MC68020EH16E?

The MC68020EH16E is packaged in a 132-pin ceramic Pin Grid Array (PGA) with RC suffix designation. Its mechanical dimensions are 39.62 mm × 39.62 mm, pin pitch is 1.27 mm, and it is designed for socketed insertion in high-reliability or field-upgradeable systems. The ceramic construction provides thermal stability and hermetic sealing for industrial environments.

How does the MC68020EH16E handle bus arbitration?

The MC68020EH16E implements three-signal bus arbitration using BR (Bus Request), BG (Bus Grant), and BGACK (Bus Grant Acknowledge). When another master asserts BR, the MC68020EH16E completes its current bus cycle, tri-states its address/data/control outputs, and releases the bus upon asserting BGACK - enabling DMA controllers or other processors to take ownership without system halt.