National Semiconductor NS638 DEC Memory Board 90010482 Phillips SPE-142-003

National Semiconductor NS638 DEC Memory Board 90010482 Phillips SPE-142-003

The National Semiconductor NS638 is a memory expansion board manufactured by Phillips Components, carrying part number SPE-142-003 and National Semiconductor board number 90010482. This large-format card is densely populated with memory ICs arranged in parallel rows across the full board surface, and interfaces to its host system via a multi-finger gold card-edge connector. It was designed for use in DEC (Digital Equipment Corporation) systems, providing additional memory capacity in compatible backplane-based configurations.

Specifications & What's Included

• Manufacturer: National Semiconductor / Phillips Components
• Model / Board Number: NS638 (90010482)
• Phillips P/N: SPE-142-003
• Type: Memory Expansion Board
• Compatible Platform: DEC / Digital Equipment Corporation systems
• Form Factor: Full-size backplane card with gold card-edge connector (three connector sections visible on solder side)
• Memory Array: Densely packed dual-inline memory IC array covering the majority of the board surface
• Additional ICs: Logic/support chips and smaller support components on left-hand section of component side
• Includes: Memory board only

Applications

Memory expansion boards of this type were used in DEC minicomputer and workstation systems — the product line that defined mid-range computing from the late 1970s through the 1990s. DEC systems such as the VAX series and their predecessors used modular backplane architectures where memory capacity was expanded by adding boards like this one. Phillips Components supplied OEM memory boards to major system manufacturers under their own part numbers (SPE-series), and these boards were commonly found in data center, engineering workstation, and scientific computing environments. Today these boards are sought by collectors and maintainers of legacy DEC hardware keeping older VAX and similar systems operational.