1. Official standard specifications (Motorola/Emerson, 100% accurate)

CPU: Motorola MC68040 32MHz (built-in FPU + MMU + 8KB unified cache)

Form: 6U dual-height (2 slots) VME SBC (same as 510A/513A/520A/521A)

DRAM: 8MB (non-parity check)

SRAM: 512KB, battery backup (NVRAM)

Flash: 1MB (board-level firmware / monitoring program)

I/O (all standard + DMA):

Ethernet: 10BASE-T (RJ45) + 10BASE2 (BNC)

SCSI-2 (50pin narrowband, hard drive / tape drive)

Serial port: 2×RS-232/422/485 (software switchable)

Parallel port: 1×Centronics (printer)

RTC: Battery-backed real-time clock

Expansion slots: 4×IndustryPack (IP) slots, no PMC slots (the only hardware difference from 521A)

VME bus: A16/A24/A32, D8/D16/D32, supports master / slave / system controller

Temperature (critical: industrial wide temperature range): -40°C ~ +85°C (standard version 522 is 0~70°C, almost all in the market are 522A)

Power supply: +5V ±5%, typical 3.5A, maximum 4.5A

II. 522A vs 513A vs 520A vs 521A (Summary of Core Differences) Table

Model CPU DRAM SCSI PMC Temperature Location

520A 32MHz 8MB ❌ ❌ 0~70℃ Basic High-End (No Storage)

513A 32MHz 8MB ✅ ❌ Old Model Mainstay (With SCSI)

522A 32MHz 8MB ✅ ❌ -40~+85℃ New Model Mainstay (Wide Temperature + SCSI)

521A 32MHz 8MB ✅ ✅ -40~+85℃ All-Purpose Ultimate (With PMC) Conclusion:

To choose SCSI + wide temperature + without PMC → Select 522A (most recommended, market mainstream)

Replace old equipment 513/513A → Direct replacement, wider temperature makes it more stable

Choose PMC high-speed expansion (fiber optic / gigabit) → Select 521A

Do not choose SCSI → Select 520A

III. Applicable scenarios (522A is the best match)

✅ Industrial control / data acquisition: power plants, rail transit, semiconductor equipment

✅ Military / aviation / vehicle: wide temperature, high shock resistance, compatible with MIL-STD-810

✅ Upgrade of old systems (513/513A → 522A): fully compatible, performance is more stable, longer lifespan

✅ Need SCSI storage (hard drives / tape drives), no need for PMC expansion

IV. Replacement relationship (100% compatible, direct insertion and removal)

Direct replacement: MVME162-513, 513A, 522 (standard version)

Upgrading: MVME162-521A (with PMC), 532A (16MB memory)

Compatible downward: MVME162-510A, 520A (function simplification)