NXP Semiconductors MC68020RC33E

Overview

MC68020RC33E from Motorola (later Freescale) is a 32-bit, second-generation enhanced microprocessor with full 32-bit data and address buses (A31–A0, D31–D0), on-chip 256-byte instruction cache, and support for coprocessor interface (CP0–CP3). It operates at 33 MHz with 5 V supply, implements pipelined architecture with exception handling, and was used in high-end workstations, industrial controllers, and early embedded computing systems requiring full M68000-family compatibility.

For engineers reviewing the MC68020RC33E datasheet, MC68020RC33E pinout, MC68020RC33E application, or MC68020RC33E equivalent, key selection considerations include its 33 MHz clock rating, 32-bit synchronous/asynchronous bus interface, supervisor/user privilege model, cache-enabled execution, and compatibility with MC68881/882 FPU and MC68451 MMU.

Technical Context

The MC68020RC33E implements a five-stage pipeline (fetch, decode, execute, memory access, write-back) with dynamic bus sizing and misaligned operand support. Its bus interface supports asynchronous timing with DSACK0/DSACK1 handshaking and includes dedicated function code (FC2–FC0), transfer size (SIZ1/SIZ0), and bus arbitration signals (BR, BG, BGA).

It features a 256-byte on-chip instruction cache organized as 64 lines of 4 bytes each, controlled via CACR register, and supports coprocessor communication through dedicated CIR registers and response primitives. Exception processing uses a 256-entry vector table with stack frame formats defined per exception type.

Key Specifications

Pinout & Package

MC68020RC33E is housed in a 169-pin ceramic pin-grid array (PGA) package with 19×19 staggered pin layout and 0.100" pin pitch. Thermal resistance (θ_JA) is 25°C/W; mounting requires compliant socket or solder-down carrier per Motorola Mechanical Data Bulletin.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68020RC33E, MC68030RC33 adds integrated data cache and MMU for enhanced OS support, while MC68EC020RC33 trades address space for lower cost and power-both retain binary compatibility but differ in memory management capability and system scalability.

Availability

MC68020RC33E is available at Aetrix Electronics and suitable for legacy workstation upgrades, industrial controller refurbishment, and avionics maintenance programs requiring stable component supply and long-term obsolescence mitigation.

Supply support for MC68020RC33E 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 company known for the 68000 family, RF power transistors, and automotive ICs before its acquisition by NXP in 2015.

The MC68020RC33E belongs to Motorola's second-generation 32-bit microprocessor line designed for high-performance embedded and general-purpose computing systems requiring full M68000 software compatibility and scalable memory architecture.

FAQ

What is the maximum operating frequency of the MC68020RC33E?

The MC68020RC33E is rated for a maximum clock frequency of 33 MHz, as confirmed by Motorola's Electrical Characteristics specification (Section 10.3). This rating assumes nominal 5.0 V supply, ambient temperature ≤70°C, and proper decoupling. Operation above 33 MHz violates AC timing parameters and may result in instruction fetch errors or bus protocol violations.

Does the MC68020RC33E include an integrated memory management unit (MMU)?

No, the MC68020RC33E does not integrate an MMU. It supports external MMUs such as the MC68451 via its coprocessor interface and bus control signals, but lacks on-die translation lookaside buffers (TLBs) or page table walkers. MMU functionality must be implemented externally, unlike the later MC68030 which integrates both instruction and data caches plus an MMU.

What package type is used for the MC68020RC33E?

The MC68020RC33E uses a 169-pin ceramic pin-grid array (PGA) package, denoted by the "RC" suffix in the part number. This package features a 19×19 staggered pin layout with 0.100" pin pitch and is specified in Motorola's Mechanical Data Bulletin for thermal and mechanical mounting requirements.

Can the MC68020RC33E interface directly with the MC68881 floating-point unit?

Yes, the MC68020RC33E supports direct coprocessor interface with the MC68881 FPU using its CP0–CP3 control lines and dedicated CIR registers. The MC68020RC33E's coprocessor protocol - including busy primitive handshake and operand transfer primitives - is fully compatible with MC68881 timing and command sets as documented in the M68020 User's Manual Sections 7 and 9.1.

What is the function of the DSACK0 and DSACK1 pins on the MC68020RC33E?

The DSACK0 and DSACK1 pins on the MC68020RC33E are data strobe acknowledge outputs used to configure bus cycle timing. Their logic states determine wait state insertion: DSACK0=H/DSACK1=L indicates one wait state; both pins low indicates two or more wait states. External logic (e.g., PAL or discrete gates) must drive these signals based on peripheral readiness to meet the MC68020RC33E's timing requirements.