AST 386/25 Processor Board 202274-001 Intel 386 CPU ISA 16-bit PC Motherboard

AST 386/25 Processor Board 202274-001 Intel 386 CPU ISA 16-bit PC Motherboard

The AST 386/25 Processor Board (part number 202274-001) is a full-length ISA processor card designed for AST Research 386-class desktop and tower systems. It carries two Intel 386 (i386) CPUs running at 25 MHz along with supporting logic, a VLSI chipset, and onboard SIMM memory sockets, providing the core processing and memory subsystem for the host system. This is a board-level processor card — not a standalone motherboard — intended to slot into an ISA bus chassis that supplies I/O and expansion.

Specifications & What's Included

• Manufacturer: AST Research
• Board designation: 386/25 (386-CPU)
• Part number: 202274-001 (full assembly: 202274-001003004)
• Hardware revision: Rev F (per board label)
• Primary CPUs: Two Intel 386 (i386) processors, 25 MHz
• Support chipset: VLSI V63C328J02 (date code 9036 — week 36, 1990)
• Memory: Onboard SIMM sockets (Bank 0–2 visible, SIMM0 area populated with multiple DIP RAM ICs)
• Bus interface: ISA 16-bit, full-length card
• Additional logic ICs: TI 74F74N, M68B024, M68B042, and other support chips visible on board
• Form factor: Full-length ISA expansion card with rear bracket
• Country of manufacture: Malaysia (per IC markings)
• Included: Board only — no cables, manuals, or accessories

Applications

AST Research was a major PC manufacturer in the late 1980s and early 1990s, and their 386-series processor boards were used in proprietary desktop and tower chassis that accepted modular processor cards over the ISA bus. This design allowed the CPU subsystem to be upgraded independently of the rest of the chassis — a common approach among business-class PC makers of the era. The AST 386/25 dates from approximately 1990, squarely in the period when the Intel 386 (introduced in 1985) was the mainstream business desktop processor before the 486 generation took over. Today, boards like this are sought by vintage PC collectors, retro-computing enthusiasts, and anyone maintaining or restoring period-correct AST 386 systems. The ISA bus and socketed DIP chips are characteristic of late-1980s/early-1990s PC architecture.